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OpenBTS Application Suite User Manual

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1. e ee 28 4 3 TMSI Table 22 30225020 3er 29 4 4 Transaction Table lt lt ee a 30 4 5 Chan el Table aici pars ma ke eh a aaa a asa OU a 30 4 1 Manipulating OpenBTS Databases The following methods can be used to view and modify the OpenBTS database files e OpenBTS Command Line Interface CLI The OpenBTS CLI config and unconfig commands Section 3 3 can be used to edit the OpenBTS configuration table Section 4 2 in real time Configuration changes from the CLI are written back to the OpenBTS db database and are persistent Some changes may require a restart of OpenBTS before they take effect e OpenRANUI web interface This tool is only available in the Commercial version All customer tuneable parameters can be modified via the web interface from the Configuration panel Additionally the Databases panel provides read only access with sorting and search capabilities to all major run time tables The above mentioned methods of manipulating the databases ensure the integrity of the OpenBTS related databases and should be considered the methods of choice In the laboratory or development environment it might be occasionally useful to access the databases directly e The sqlite3 tool The sqlite3 command line tool can be used to inspect and modify these databases using SQL syntax 27 28 CHAPTER 4 OPENBTS DATA TABLES AND STRUCTURES The database can be manipulated d
2. Codec per call per call 7 calls 7 calls speech raw rate over RTP over RTP IAX trunking quality G 711 64 81 567 468 toll quality GSM FR 13 30 210 124 toll quality G 729 8 25 175 97 near toll quality Speex 8 25 175 97 near toll quality Speex 4 21 147 60 not toll quality LPC 10 2 4 20 136 37 not toll quality Table 6 1 shows the required bandwidth for common combinations of codecs and protocols Codecs with toll quality speech are suitable for use in public networks under any conditions Codecs with near toll quality speech are suitable for public networks in remote areas where the only other option would be no service at all Codecs that are not toll quality are not suitable for use in public networks but may be useful in private networks in remote areas where backhaul costs are high The importance of IAX trunking in reducing bandwidth is obvious regardless of codec type Satellite Backhaul Satellite based sites are exquisitely sensitive to bandwidth requirements The specific recommendation for satellite based OpenBTS sites is for all of the BTS units at the site to route all non local calls through a pair of Asterisk servers as shown in Figure 6 5 The recommended codec types would be GSM FR Speex or LPC 10 depending on budgets and user expectations the important part is to use IAX trunking 6 6 BACKHAUL CAPACITY CONSIDERATIONS Satellite Based Site OpenBTS APs e
3. ye n L IAX IAX SIP RTP 11 3 SIP RTP Local _ jax _ N ha _1ax Remote switch 4 A switch SIP RTP g 7 LE Figure 6 5 Paired Asterisk servers for AX trunking in satellite based applications 49 Chapter 7 SMQueue 7 1 Design and Operation of SMQueue 0002 eee ee ee 50 7 1 1 Addressing in SMQueue 2 2 a 50 7 2 Configuring SMQueue ai 2 ee ee ee ee 51 7 3 Short Code Applications e ma 51 7 3 1 Existing Short Code Applications o o 51 1 3 2 Short Code Implementation s si sa saosa sanad t go aa a a a 52 The delivery of each text message depends on a store and forward facility in the network SMQueue provides this facility The SMQueue source code is publicly available under AGPLv3 See Appendix section A 2 for details on SMS implementation in OpenBTS and SMQueue and references to the relevant GSM standards 7 1 Design and Operation of SMQueue The core of SMQueue is a queue of messages awaiting delivery Messages wait in this queue potentially through multiple delivery attempts until delivery is confirmed or until the message is determined to be undeliverable The operation is similar to that of an email server 7 1 1 Addressing in SMQueue SMQueue recognizes two kinds of addresses ISDN E 164 numeric addresses and SIP usernames Any all numeric address is assumed to be an ISDN E 164 address and SMQueue will attempt to resolve it to a SIP
4. 3 1 Accessing the System All Range installations of OpenBTS Release 4 0 run Ubuntu Linux v12 04 operating system The primary interface to the system is the UNIX shell accessed via ssh from the Ethernet connector on the front panel The system s Ethernet interface is auto sensing requiring no hub or crossover cable It is shipped with the default IP address of 192 168 0 21 Once the unit is connected to another computer or a network on the 192 168 0 x subnet it can be accessed via ssh The account is as follows 19 20 CHAPTER 3 GETTING TO KNOW YOUR OPENBTS SYSTEM Login openbts Password openbts The account is super user sudo enabled The command to issue on any UNIX system including OS X is ssh openbts0192 168 0 21 From a Windows machine an SSH client like PuTTY can be used Note Make sure to change the password for user openbts before you connect the system to the public network 3 2 Starting and Stopping Applications In embedded configurations used in Range systems all applications in the OpenBTS Application Suite are configured as upstart services visit upstart ubuntu com for further details and start during system initialization Should either one crash or exit it will automatically restart To manually start an application log into the system and type at the command line sudo start lt application_name gt To stop an application sudo stop lt application_name gt To restart OpenBTS
5. Non Dedicated Control Channels NDCCHs These are unicast and broadcast channels that do not have analogs in ISDN These channels are used almost exclusively for radio resource management The CCCH and RACH together form the medium access mechanism for Um Broadcast Control Channel BCCH The BCCH carries a repeating pattern of system information messages that describe the identity configuration and available features of the BTS The COTO beacon channel must carry an instance of the BCCH Synchronization Channel SCH The SCH transmits a Base station identity code and the current value of the TDMA clock The COTO beacon channel must carry an instance of the SCH Frequency Correction Channel FCCH The FCCH generates a tone on the radio channel that is used by the MS to discipline its local oscillator A 1 THE OPENBTS GSM AIR INTERFACE 69 Common Control Channel CCCH The CCCH is a downlink unicast channel that carries paging requests and channel assignment messages specifically immediate assignment messages The CCCH is subdivided into the paging channel PCH and access grant channel AGCH An MS that is camped to a BTS monitors the PCH for service notifications from the network Random Access Channel RACH The RACH is the uplink counterpart to the CCCH The RACH is a shared channel on which the MSs transmit random access bursts to request channel assignments from the BTS assignments which are granted on the AGCH part of the CCCH
6. FEC Coding The coding sublayer provides forward error correction As a general rule each GSM channel uses a block parity code usually a Fire code a rate 1 2 4th order convolutional code and a 4 burst or 8 burst interleaver Notable exceptions are the synchronization channel SCH and random access channel RACH that use single burst transmissions and thus have no interleavers For speech channels vocoder bits are sorted into importance classes with different degrees of encoding protection applied to each class GSM 05 03 Using soft input Viterbi decoding the FEC decoders in OpenBTS can recover frames reliably with bit erasure rates in excess of 25 Most channels in GSM use 456 bit L1 frames On channels with 4 burst interleaving BCCH CCCH SDCCH SACCH these 456 bits are interleaved in to 4 radio bursts with 114 payload bits per burst On channels with 8 burst interleaving TCH FACCH these 456 bits are interleaved over 8 radio bursts so that each radio burst carries 57 bits from the current L1 frame and 57 bits from the previous L1 frame Interleaving algorithms for the most common traffic and control channels are described in GSM 05 03 Sections 3 1 3 3 2 3 and 4 1 4 A 1 THE OPENBTS GSM AIR INTERFACE 67 Data Link Layer L2 The Um data link layer LAPDm is defined in GSM 04 05 and 04 06 LAPDm is the mobile analog to ISDN s LAPD and like LAPD LAPDm is a simplified form of HDLC Network Layer L3 Um L3 is defined in GSM
7. GGSN Shell Script This is intended primarily for telemetry applications OpenBTS can invoke a shell script each time a new MS device activates GPRS services or creates an IP connection The GGSN ShellScript parameter is set to the name of a UNIX shell script The arguments passed to the shell script for each action and the significance of the action are as follows e Start The system has started e GprsAttach lt IMSI gt MS specified by lt IMSI gt has GPRS attached e GprsDetach lt IMSI gt MS specified by lt IMSI gt has GPRS detached or attach has expired e PdpActivate lt IMSI IPaddress NSAPI gt MS specified by lt IMSI gt has activated an lt lPaddress gt Each MS may activate up to 11 IP addresses numbered by lt NSAPI gt which is numbered from 5 to 15 e PdpDeactivate lt IMSI IPaddress NSAPI gt MS specified by lt IMSI gt has deactivated an lt lPaddress gt numbered by lt NSAPI gt e PdpDeactivateAll lt IMSI gt Deactivate all IP addresses for the specified MS there may be none Notes 1 The shell script invocation is serialized by OpenBTS so only one shell script runs at a time In future versions of OpenBTS a and Tc will adapt automatically based on uplink RSSI measurements 84APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS 2 The shell script does not provide any way to prevent an MS from attaching in the first
8. Server 2 subscriber registry 12 smqueue i SIP switch tg subscriber registry smqueue Figure E 2 Improved mobility architecture For simplicity only two cell sites are shown each with three units e All BTS units have different ARFCNs and each BTS unit has a neighbor list that lists the ARFCNs of any nearby units e BTS units in each site designate the site local servers as their SIP proxies for all services Units 1A 1B and 1C list the servers in S1 as their SIP Proxy parameters Units 2A 2B and 2C list the servers in S2 as their SIP Proxy parameters The configuration rules for the servers are e The subscriber registry servers in S1 and S2 point to the subscriber registry server in CS as their upstream server e The Asterisk servers in S1 and S2 are configured to refer any call whose destination number cannot be resolved locally to the central Asterisk server in CS e The SMQueue servers in S1 and S2 are configured to refer any message whose destination number cannot be resolved locally to the central SMQueue server in CS e Any transaction for which the central servers in CS cannot resolve an address is referred to an external network or service E 4 Handover In conventional GSM networks handover is coordinated by a BSC or MSC that the two BTS units have in common In OpenBTS networks handover is coordinated by the BTS units themselves using the Range Peering Protocol RPP On the air interface Um
9. c option followed by a command makes the CLI execute the command print the result to STDOUT and exit No banners welcome messages appear in the output gt OpenBTS OpenBTSCLI c cellid MCC 001 MNC 01 LAC 1010 CI 10 24 CHAPTER 3 GETTING TO KNOW YOUR OPENBTS SYSTEM Alternatively the d option starts the CLI and awaits a command on the STDIN executes it prints the result to STDOUT and exits Note The d option repeats the functionality of the OpenBTSDo script from the earlier versions of OpenBTS The script is still available in the current release for backward compatibility 3 4 Using the OpenRANUI The commercial release of OpenBTS includes a web enabled administrative interface called OpenRANUI It allows you to monitor and confugire your OpenBTS application suite It is available via HTTP interface at the following location provided that the BTS operates at the default 192 168 0 21 IP address and can be accessed using any modern time web browser http 192 168 0 21 ranui The login to access the OpenRANUI is openbts and the password matches the system password for the same account openbts by default 3 4 1 Starting and Stopping Applications of OpenBTS Suite The Services panel provides the system health information and allows to start and stop individual services Click on the manage node button to reveal the version information for every component running on a node T
10. e FEC Coding This sublayer provides bit error concealment and recovery This sublayer is defined in GSM 05 03 Radiomodem OpenBTS supports GMSK modulation with a 13 48 MHz 270 833 kHz symbol rate and a channel spacing of 200 kHz Since adjacent channels overlap the standard does not allow adjacent channels to be used in the same cell OpenBTS supports the four most common GSM bands e GSM850 used in parts of ITU region 2 66APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS e PGSM900 and EGSM900 used in most of the world e DCS1800 used in most of the world e PCS1900 used in parts of ITU region 2 GSM is frequency duplexed meaning that the network and MS transmit on different frequencies allowing the BTS to transmit and receive at the same time Transmission from the network to the MS is called downlink Transmission from the MS to the network is called uplink GSM uplink and downlink bands are separated by 45 or 50 MHz depending on the specific band Uplink downlink channel pairs are identified by an index called the ARFCN Within the BTS these ARFCNs are given arbitrary carrier indexes CO C1 etc with CO designated as a Beacon Channel and always operated at constant power The radio channel is time multiplexed into 8 timeslots each with a duration of 156 25 symbol periods These 8 timeslots form a frame of 1 250 symbol periods The capacity associated with a single timeslot on a
11. GPRS RA COLOUR GPRS Routing Area Color as advertised in the COTO beacon GPRS RRBP Min Minimum value for Relative Reserved Block Period RRBP reservations range 0 3 Should normally be 0 A non zero value gives the MS more time to respond to the RRBP request B 1 OPENBTS PARAMETERS 95 GPRS SendIdleFrames Should be O for current transceiver or 1 for deprecated version of transceiver GPRS TBF Downlink Pol11 When the first poll is sent for a downlink tbf measured in blocks sent GPRS TBF Expire How long in milliseconds to try before giving up on a TBF GPRS TBF KeepExpiredCount How many expired TBF structs to retain they can be viewed with gprs list tbf x GPRS Timers Channels Idle How long in milliseconds a GPRS channel is idle before being returned to the pool of channels Also depends on Channels Min Currently the channel cannot be returned to the pool while there is any GPRS activity on any channel GPRS Timers MS Idle How long in seconds an MS is idle before the BTS forgets about it GPRS Timers MS NonResponsive How long in milliseconds a TBF is non responsive before the BTS kills it GPRS Timers T3169 Nonresponsive uplink TBF resource release timer in milliseconds See GSM04 60 Sec 13 GPRS Timers T3191 Nonresponsive downlink TBF resource release timer in milliseconds See GSM04 60 Sec 13 GPRS Timers T3193 Timer T3193 in milliseconds in the b
12. GPRS Multislot Max Uplink Maximum number of channels used for a single MS in uplink GPRS NMO Network Mode of Operation See GSM 03 60 Section 6 3 3 1 and 24 008 4 7 1 6 Allowed values are 1 2 3 for modes Il Ill Mode II 2 is recommended Mode implies combined routing updating procedures GPRS Reassign Enable Enable TBF Reassignment GPRS TBF EST Allow MS to request another uplink assignment at end up of uplink TBF See GSM 4 60 9 2 3 4 GPRS TBF Retry If 0 no tbf retry otherwise if a tbf fails it will be retried with this codec numbered 1 4 GSM CCCH AGCH QMax Maximum number of access grants to be queued for transmission on AGCH before declaring congestion GSM Cell0ptions RADIO LINK TIMEOUT Seconds before declaring a physical link dead GSM CellSelection CELL RESELECT HYSTERESIS Cell Reselection Hysteresis See GSM 04 08 10 5 2 4 Table 10 5 23 for encoding Encoding is 2N dB values of N are 0 7 for 0 14 dB GSM CellSelection NCCsPermitted NCCs Permitted An 8 bit mask of allowed NCCs The NCC of your own network is automatically included Unless you are coordinating with another carrier this should be left at zero 90 APPENDIX B CONFIGURATION PARAMETERS GSM CellSelection NECI NECI New Establishment Causes This must be set to 1 if you want to support very early assignment VEA It can be set to 1 even if you do not use VEA so you might as well leave it a
13. More Advanced Case The simple example in the previous section is easy to understand and easy to configure but has some weaknesses e If a BTS unit loses connectivity to the core network due a backhaul failure that unit will cease to provide any services e All database call routing and message routing loads are concentrated in the central servers limiting scalability We can improve the performance and reliability of the network by using additional server sets inside the BTS units themselves or at each cell site as shown in Figure E 2 The available ARFCNs are 40 45 and the IP addresses are in the 192 168 0 x range The short summary of this configuration is that all of the OpenBTS units in each site point to the local server at that site S1 and S2 in the figure Servers S1 and S2 may be separate server machines in the cell sites with the BTS units or may use computational resources of one of the OpenBTS units as shown in Figure 2 2 For brevity we will not show the entire configuration for all of the devices in this network but the general rules and patterns for BTS configuration are e All BTS units have the same MCC MNC and NCC All units have the same NCCs permitted mask set to select the NCC that is used e All BTS units have different LAC Cl and BCC E 4 HANDOVER 123 12 ty SIP switch IP EAM 12 subscriber registry l iia private Central Qpenals IP network Server APs tg SIP switch oe
14. Once finished do not forget to restart the OpenBTS openbts ubuntu sudo start openbts The results of the most recent scan are available in the var run OpenBTS PowerScannerResults db database They are also accessible via the OpenRAN web Ul in the Power Scanner table found in the Databases panel 62 Appendices Appendix A OpenBTS Implementation of GSM amp 3GPP Specifications and IETF Standards A 1 The OpenBTS GSM Air Interface o 0 0202 ee ee 64 AL Um Layer outra Goa eee PAE AG Owe He eee t 65 ALZ Um logical channels 44 00 o ae a ee ae a 67 AS Security on Um brida Gore a ee be a ad 69 AAA Service Capacity of Umi s sa a we ke eee ek a a ee a 70 A 2 Text Messaging SMS sec s eo ee de a ee eg ea ee a a a 72 A 2 1 Internet Messaging Protocols c e a saucen waa raa 2 o 73 A 2 2 Text Messaging in GSM 2 e 73 A 3 Short Message Service Cell Broadcast SMSCB o ooo 76 A 3 1 Cell Broadcast Channel CBCH 2 2 76 A 3 2 Scheduling Messages for Delivery 2 2 2 o 76 A 4 General Packet Radio Service GPRS o o 77 AAT Components of GPRS e cot east anapeana a a ae a 78 A 4 2 Use of NAT and Security Implications ooo a 78 A 4 3 Radio Resource Management and Performance in GPRS 79 It is not really necessary to fully understand this chapter to use OpenBTS but the information is given here for com
15. OpenBTS implementation of GPRS differs significantly from conventional networks See Appendix section A 4 for details on GPRS implementation in OpenBTS and references to relevant standards 9 1 Configuring GPRS in OpenBTS A number of parameters need to be configured verified before the GPRS service would become available on your BTS The primary parameter which enables or disables the GPRS function is GPRS Enable lt can be edited using the OpenBTS CLI or OpenRANUI web interface and requires a restart of OpenBTS 9 1 1 Assigning a Range of IP Addresses to GPRS OpenBTS uses the built in NAT Network Address Translation function of the Linux kernel to assign IP ad dresses to GPRS handsets The range of available addresses is defined by configuration parameters GGSN MS IP Base 54 9 1 CONFIGURING GPRS IN OPENBTS 55 and GGSN MS IP MaxCount Additionally the GGSN MS IP Route and GGSN DNS parameters can be used to specify the route address and the DNS Their default values are as follows e GGSN MS IP Base 192 168 99 1 e GGSN MS IP MaxCount 254 In the default configuration IP addresses will be assigned from the range of 192 168 99 1 192 168 99 255 They will expire after the amount of seconds specified in the GGSN IP ReuseTimeout developer configuration parameter e GGSN MS IP Route disabled When not specified explicitly OpenBTS manufactures this value from the GGSN MS IP Base assuming a 24 bit ma
16. UMTS LTE IP multimedia call control protocol based on Session Initiation Protocol SIP and Session Description Protocol SDP Stage 3 1 6 3 IETF This document references the following IETF standards which can be downloaded for free from the ietf org web site 1 7 CONTACT INFORMATION amp SUPPORT 13 e RFC 2833 RTP Payload for DTMF Digits Telephony Tones and Telephony Signals e RFC 2976 The SIP INFO Method e RFC 3261 SIP Session Initiation Protocol e RFC 3325 Private Extensions to the Session Initiation Protocol SIP for Asserted Identity within Trusted Networks e RFC 3428 Session Initiation Protocol SIP Extension for Instant Messaging e RFC 3455 Private Header P Header Extensions to the Session Initiation Protocol SIP for the 3rd Generation Partnership Project 3GPP e RFC 3550 RTP A Transport Protocol for Real Time Applications e RFC 4119 A Presence based GEOPRIV Location Object Format 1 7 Contact Information amp Support 1 7 1 Direct Contact For additional information or paid technical support for OpenBTS please contact Range Networks Inc 560 Brannan Street San Francisco California 94107 United States of America telephone 1 415 778 8700 email supportOrangenetworks com 1 7 2 Online Resources Customer Support System A support agreement with Range Networks includes a subscription to the customer support web site wiki and forum Fo
17. agement loop attempts to achieve If the actual value of T3122 is larger than this the BTS will reduce its output power If the actual value of T3122 is small than this the BTS will increase its output power if it is not already maximized It is critical that this target value be within the bounds set by GSM Timer T3122Max and GSM Timer T3122Min as described in Section 5 1 1 32 5 1 DOWNLINK POWER AND CONGESTION MANAGEMENT 33 e GSM Radio PowerManager Period This is the adaptation time constant in milliseconds e GSM Radio PowerManager MaxAttenDB The maximum allowed attenuation in dB relative to full power which determines the minimum output level This is also the initial attenuation level e GSM Power PowerManager MinAttenDB The minimum allowed attenuation in dB relative to full scale which determines the maximum output level This value is normally zero allowing the BTS to operate at the maximum power level supported by the hardware To disable the automatic power control feature set the minimum and maximum attenuation levels MaxAttenDB and MinAttenDB to the same value usually zero for maximum power at all times The CLI power command described in Section C 19 can be used to monitor this mechanism or to control upper and lower power bounds as a pair 5 1 1 T3122 Exponential Back Off When too many MSs make simultaneous access attempts to the BTS resulting in channel exhaustion the BTS can respond on
18. cross refs TRANSACTION_TABLE strings of the same format are used in the CHANNEL column of the Transaction table to allow cross referencing ARFCN INTEGER DEFAULT NULL the ARFCN of this channel ACCESSED INTEGER DEFAULT 0 Unix time of the most recent update of the record RXLEV_FULL_SERVING_CELL INTEGER DEFAULT NULL downlink RSSI in dBm as observed by the handset averaged over all timeslots on this ARFCN RXLEV_SUB_SERVING_CELL INTEGER DEFAULT NULL downlink RSSI in dBm as observed by the handset for this timeslot RXQUAL_FULL_SERVING_CELL_BER FLOAT DEFAULT NULL downlink BER in percent as observed by the handset averaged over all timeslots on this ARFCN RXQUAL_SUB_SERVING_CELL_BER FLOAT DEFAULT NULL downlink BER in percent as observed by the handset for this timeslot RSSI FLOAT DEFAULT NULL uplink RSSI at the BTS receiver expressed in dB relative to full scale input this is normally within a few dB of the GSM Radio RSSITarget parameter TIME_ERR FLOAT DEFAULT NULL timing advance error in symbol periods this is normally accurate to better than 1 20 of a symbol period reported at a resolution of 1 256 of a symbol period TRANS_PWR INTEGER DEFAULT NULL MS transmitter power in dBm TIME_ADVC INTEGER DEFAULT NULL MS timing advance in whole symbol periods FER FLOAT DEFAULT NULL observed uplink FER for the channel NCELL_ARFCN INTEGER DEFAULT NULL ARFCN of the strongest neighbor NC
19. e Control LUR OpenRegistration Reject is 0 3 Accept all handsets except those from the US e Control LUR OpenRegistration is e Control LUR OpenRegistration Reject is 7310 4 Accept all US handsets except those from AT amp T e Control LUR OpenRegistration is 310 e Control LUR OpenRegistration Reject is 310410 42 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK 6 2 4 Generating Custom SIMs Range offers writable SIMs part 8430 xxx series and SIM writers part 48425 xxx series that allow an operator to generate COMP128v1 SIMs with known IMSI s and known Ki s supporting full RAND SRES au thentication The OpenBTS application suite includes the software to automate the provisioning process for SIM cards generated using the SIM writer In the commercial release the RangeSIMd application is integrated with the OpenRANUI web interface With the SIM writer attached to the BTS and RangeSIMd running access the web UI and select the Sub scribers panel Click on write SIM verify that the SIM writer status is ready specify the subscriber s name and phone number and click on write The record will automatically be added to the Subscriber Registry Users of the public release can download and install application called PySIM which programs SIMs from the command line Additional informaiton available in the OpenBTS wiki 6 2 5 Roaming SIMs For informat
20. followed by the digits of the IMSI e To support full authentication the subscriber requires a Ki value If no Ki value is provided OpenBTS cannot use A3 authentication and will use cached authentication instead See Section 6 1 3 6 2 PROVISIONING NEW SUBSCRIBERS 39 6 2 1 Using Pre existing SIMs OpenBTS systems can use pre existing SIMs even in the absence of a carrier roaming agreement although full RAND SRES authentication cannot be used because Ki is not known Manually The key to manual provisioning is to determine the IMSI of the SIM used in the MS Some possible ways to do this are 1 Locate the IMSI in the TMSI table of the serving BTS with the tmsis CLI command or using the OpenRANUI web interface select the Databases panel and pick the TMSI table from the drop down list of available databases 2 Enable the Control LUR FailedRegistration Message feature using the corresponding OpenBTS configuration parameter to deliver a welcome message to unprovisioned MSs The message is automat ically appended with the IMSI digits A typical message might be To activate service bring this code to our office See Section 4 2 for more information Once the IMSI is known the operator can generate an entry in the Subscriber Registry and assign a phone number to the subscriber in the OpenBTS network To do so in the commercial release use the Subscribers panel of the OpenRANUI web interface
21. in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty keep intact all the notices that refer to this General Public License and to the absence of any warranty and give any G 2 GNU GENERAL PUBLIC LICENSE V 1 141 other recipients of the Program a copy of this General Public License along with the Program You may charge a fee for the physical act of transferring a copy 2 You may modify your copy or copies of the Program or any portion of it and copy and distribute such modifications under the terms of Paragraph 1 above provided that you also do the following a cause the modified files to carry prominent notices stating that you changed the files and the date of any change and b cause the whole of any work that you distribute or publish that in whole or in part contains the Program or any part thereof either with or without modifications to be licensed at no charge to all third parties under the terms of this General Public License except that you may choose to grant warranty protection to some or all third parties at your option c If the modified program normally reads commands interactively when run you must cause it when started running for such interactive use in the simplest and most usual way to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty or else saying
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23. seen Command ste s a amos sioe a RA ee ewe es 112 shutdown Command ceo aa ele RURE eee a a EEA 112 C 1 ALARMS COMMAND 103 C 27 stats Command sos s soa 66 2 cria ae Se ee 113 C 28 sysinfo Command esca we a a ee a we ea a 113 C 29 tmsis Command lt ss ecese sassa we arier uw ee ee aeS 113 C30 trans Command itine d ates IA IRA AA A e RAE a BES 114 C 31 trxfactory Command lt s lt s ss ieee ee koa t sanis tarut 114 C 32 txatten Command lt e ee e sosa sea RAR A 114 C 33 unconfig Command s a poire s a ei e O CAOR a ee 115 C 34 uptime Command 2 i ee ee a kiusana 115 C 35 version Command xsara eR ea o a a eee a 115 C 36 Executing OS shell commands from the CLI o 115 C 1 alarms Command List recent alarms The number of alarms shown in the list is set by the Log Alarms Max configuration value C 2 audit Command Examines the current configuration and reports possible issues Troubleshooting information includes the fol lowing severity levels and sections ERROR keys with invalid values e WARNING keys which differ from factory radio calibration values only available with Range Networks radio hardware e WARNING interaction among values which could cause problems e WARNING site specific keys which are still set to their default values INFO keys with non default values e INFO depreca
24. username using the subscriber registry Any address that is not all numeric is assumed to be a SIP username in the operator s network 50 7 2 CONFIGURING SMQUEUE 51 7 2 Configuring SMQueue In the commercial release SMQueue comes preconfigured The configuration is stored in an sqlite3 database table located at etc OpenBTS smqueue db lt uses the same schema as the OpenBTS configuration table OpenRANUI web interface is used to configure SMQueue in commercial installations Select the smqueue tab in the Configuration panel SMQueue parameters are grouped into basic and advanced Currently the configuration can be changed only by restarting SMQueue after changing the database Some configuration parameters of note are e SIP myIP The IP address of the machine running SMQueue as seen by the Subscriber Registry server e SIP myIP2 The IP address of the machine running SMQueue as seen by remote gateways e SIP GlobalRelay The IP address port and other parameters of a remote RFC 3428 server for delivery of non local messages If no such gateway is available these parameters should be left empty This set of parameters can be used to build a hierarchy of SMQueue servers for large networks e BounceMessage A set of error messages sent back to MSs when submitted messages are undeliverable e SC Configuration parameters for specific short code functions not for SMQueue itself See Section
25. 10 2 2 indicates MS must get a block every 360ms GPRS Downlink Persist After completion downlink TBFs are held open for this time in milliseconds If non zero must be greater than GPRS Downlink KeepAlive GPRS MS KeepExpiredCount How many expired MS structs to retain they can be viewed with gprs list ms x GPRS MS Power Alpha MS power control parameter unitless in steps of 0 1 so a parameter of 5 is an alpha value of 0 5 Determines sensitivity of handset to variations in downlink RXLEV Valid range is 0 10 for alpha values of 0 1 0 See GSM 05 08 10 2 1 GPRS MS Power Gamma MS power control parameter in 2 dB steps Determines baseline of handset uplink power relative to downlink RXLEV The optimum value will tend to be lower for BTS units with higher power output This default assumes a balanced link with a BTS output of 2 4 W ARFCN Valid range is 0 31 for gamma values of 0 62 dB See GSM 05 08 10 2 1 GPRS MS Power T_AVG_T MS power control parameter see GSM 05 08 10 2 1 GPRS MS Power T_AVG_W MS power control parameter see GSM 05 08 10 2 1 GPRS NC NetworkControlOrder Controls measurement reports and cell reselection mode MS au tonomous or under network control should not be changed See GSM 5 08 10 1 4 GPRS PRIORITY ACCESS THR Code contols GPRS packet access priorities allowed See GSM04 08 table 10 5 76 GPRS RAC GPRS Routing Area Code advertised in the COTO beacon
26. 11 of the WIPO copyright treaty adopted on 20 December 1996 or similar laws prohibiting or restricting circumvention of such Measures When you convey a covered work you waive any legal power to forbid circumvention of technological measures to the extent such circumvention is effected by exercising rights under this License with respect to 156 APPENDIX G FOSS LICENSES the covered work and you disclaim any intention to limit operation or modification of the work as a means of enforcing against the work s users your or third parties legal rights to forbid circumvention of technological measures 4 Conveying Verbatim Copies You may convey verbatim copies of the Program s source code as you receive it in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice keep intact all notices stating that this License and any non permissive terms added in accord with section 7 apply to the code keep intact all notices of the absence of any warranty and give all recipients a copy of this License along with the Program You may charge any price or no price for each copy that you convey and you may offer support or warranty protection for a fee 5 Conveying Modified Source Versions You may convey a work based on the Program or the modifications to produce it from the Program in the form of source code under the terms of section 4 provided that you also meet all of the
27. 4 1 Components of GPRS A conventional GPRS network uses these components e GPRS capable BTS Base Transceiver Station which supports packet transfer on the air interface e GPRS capable BSC Base Station Controller which provides GPRS specific radio resource management e SGSN Serving GPRS Support Node which manages GPRS sessions between the network and handset e GGSN Gateway GPRS Support Node which connects GPRS sessions to the internet This is where IP addresses get associated with GPRS sessions In the OpenBTS implementation of GPRS all of these functions are incorporated into the OpenBTS stack Still these functional elements are referred to by their conventional names in documentation and configuration parameters to avoid confusion A 4 2 Use of NAT and Security Implications The OpenBTS GGSN function uses the built in NAT Network Address Translation function of the Linux kernel to assign IP addresses to GPRS handsets Because of the way NAT is implemented in Linux systems handsets do not have publicly routable IP addresses not even dynamic ones A handset s IP address as known to the outside world will be the same as that of its serving BTS unit The OpenBTS use of NAT for GGSN functions has security implications that must be understood by the operator to avoid insecure configurations lt is very important that operators read and understand this section Since the GPRS enabled device is assigned an IP address inside
28. 5 This layer terminates in the MSC L4 the relay layer is defined in GSM 04 11 Section 6 This layer terminates in the MSC GT ER es aS L5 the transfer layer is defined in GSM 03 40 This layer terminates in the SMSC As a general rule every message transferred in L n requires both a transfer and an acknowledgment on L n 1 In the OpenBTS implementation of SMS there is no MSC so L3 terminates in OpenBTS and L4 is a SIP relay to SMQueue which takes the place of the SMSC Layers of SMS in OpenBTS and SMQueue We will now consider the handling of each layer of SMS by OpenBTS and SMQueue 74APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS SMS in L3 The Um L3 part of SMS uses three messages e CP DATA to transfer an RPDU across Um and into L4 e CP ACK to acknowledge the transfer of an RPDU across Um and into L4 e CP ERROR to report the failure to transfer an RPDU to L4 An RPDU is a relay layer protocol data unit which is just an encapsulation of a message from L4 The operation in L3 is simple The entity that needs to transfer an RPDU sends it in a CP DATA message The receiving entity responds with CP ACK or CP ERROR Transactions are non overlapping The action of OpenBTS upon receiving CP DATA from an MS is to verify the correct encoding of the L3 part of the message and respond with CP ACK or CP ERROR OpenBTS then extracts the RPDU transfers it to SMQueue as an appli
29. 7 3 e Log Level Log Level These are logging controls that behave the same way as those in OpenBTS config See Appendix D for more information 7 3 Short Code Applications Short codes are local addresses within SMQueue that terminate in local application code A message sent to a short code becomes an input argument to a short code handler function instead of being delivered to another user Short code functions provide a means of writing interactive applications based on text messaging A typical SMS based application would normally comprise several short code addresses and handlers sharing common data 7 3 1 Existing Short Code Applications There are a few interesting short code applications built into the standard release of SMQueue although they are all simple applications each requiring only a single handler function To disable any short code function set its short code address to an empty string in the configuration table using unconfig SC lt FunctionName gt Code command in the OpenBTS CLI Not all short codes are documented here Undocumented short codes are left disabled in the default con figuration Refer to the smqueue smcommands cpp source code for information on undocumented short codes 52 CHAPTER 7 SMQUEUE Autoprovisioning Register The autoprovisioning application allows OpenBTS users to create new entries in the subscriber registry via SMS The user sends his desired telephone number i
30. Allowed channel combinations The multiplexing rules of GSM 05 02 allow only certain combinations of logical channels to share a physical channel The combinations currently supported by OpenBTS are e Combination I TCH F FACCH F SACCH This combination is used for full rate traffic It can be used anywhere but COTO e Combination V FCCH SCH BCCH CCCH 4 SDCCH 4 SACCH This is the typical COTO beacon channel combination for small cells It can be used only on COTO Since this is the only beacon channel combination currently supported by OpenBTS it must be used on COTO e Combination VII 8 SDCCH 8 SACCH This combination is used to provide additional SDCCH capacity in situations where registration loads or SMS usage may be particularly heavy lt can be used anywhere but COTO A 1 3 Security on Um GSM 02 09 defines the following security features on Um e authentication of subscribers by the network e encryption on the channel e anonymization of transactions at least partially Of these OpenBTS currently supports anonymization and authentication but not encryption Authentication relies on a secret key Ki that is unique to the subscriber Copies of Ki are held in the SIM and in the Authentication Center AuC a component of the HLR Ki is never transmitted across Um and should not be visible outside of the AuC Authentication The standard GSM authentication procedure is as follows 1 The MS starts a transac
31. FOSS LICENSES infringement or for any other reason not limited to patent issues conditions are imposed on you whether by court order agreement or otherwise that contradict the conditions of this License they do not excuse you from the conditions of this License If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations then as a consequence you may not distribute the Library at all For example if a patent license would not permit royalty free redistribution of the Library by all those who receive copies directly or indirectly through you then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Library If any portion of this section is held invalid or unenforceable under any particular circumstance the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims this section has the sole purpose of protecting the integrity of the free software distribution system which is implemented by public license practices Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system it is up to the author donor to decid
32. Now we take a look at all of the GSM layers and the SIP transactions together Mobile Terminated SMS Figure A 2 shows a complete mobile terminated SMS transfer where the network through SMQueue transfers a text message to the MS The message arrives at SMQueue from the outside world addressed either to a SIP user or to a numeric address SMQueue resolves the destination address to an IMSI based SIP user name and forwards the message to OpenBTS OpenBTS pages the MS establishes a channel transfers the message as SMS and then responds to SMQueue with 200 OK The most common failure in the mobile terminated transfer is that the MS does not respond to paging In this case SMQueue never receives any response The message remains in the SMQueue delivery queue and another delivery attempt will be made in a few minutes smqueue OpenBTS MS CHAN REQ IMMED ASSIGN gt PAGING RESP rm a CP DATA RP DATA mua PACK Q CP DATA RP ACK m CHANNEL RELEASE Figure A 2 Mobile terminated SMS transfer with no parallel call normal case Mobile Originated SMS Figure A 3 shows a complete mobile originated SMS transfer where the MS transfers a text message to SMQueue for later delivery to its addressee The message originates in the MS with a numeric address The MS establishes a radio channel to OpenBTS and then sends the text message TPDU in an RP DATA message OpenBTS translates the TPDU to a SIP MESSAGE method and sends that
33. OpenBTS TMSITable db which is set in the Control Reporting TMSITable configuration parameter The TMSI table is treated as read write by OpenBTS but should be treated as read only by other applications In flash based systems this table should be stored in a ramdisk partition The schema is CREATE TABLE IF NOT EXISTS TMSI_TABLE TMSI INTEGER PRIMARY KEY this value is used as the TMSI IMSI TEXT UNIQUE NOT NULL IMSI of the SIM IMEI TEXT IMEI of the MS if requested CREATED INTEGER NOT NULL Unix time seconds of record creation ACCESSED INTEGER NOT NULL Unix time seconds of last encounter A5_SUPPORT INTEGER encryption support in the MS if requested POWER_CLASS INTEGER power class of the MS if requested OLD_TMSI INTEGER previous TMSI from another cell or network OLD_MCC INTEGER previous network MCC OLD_MNC INTEGER previous network MNC OLD_LAC INTEGER previous network LAC kc varchar 33 default returned by the Registrar needed for ciphering RRLP_STATUS INTEGER DEFAULT O whether or not MS supports RRLP DEG_LAT FLOAT cached RRLP result DEG_LONG FLOAT cached RRLP result ASSOCIATED_URI text default Saved from the SIP REGISTER message and inserted into MOC SIP INVITE ASSERTED_IDENTITY text default Saved from the SIP REGISTER message and inserted into MOC SIP INVITE WELCOME_SENT INTEGER DEFAULT 0 0 welcome message not sent yet 1 sent
34. OpenBTS gt config SIP RegistrationPeriod SIP RegistrationPeriod 72 Note that the GSM Timer T3212 parameter should have a value which is a factor of 6 It should be smaller than the SIP registration period Setting it to 0 disables periodic registration C 22 rmconfig Command The rmconfig command followed by a key reverts the corresponding configuration parameter back to its default value If the key is a custom user defined key it gets completely removed from the configuration table rmconfig lt key gt Example OpenBTS gt rmconfig GSM Identity MCC GSM Identity MCC set back to its default value C 23 rxgain Command The rxgain command prints or sets the receiver gain When called without parameters it prints the current RX gain in dB stored in the GSM Radio RxGain parameter OpenBTS gt rxgain current RX gain is 47 dB 112 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE The ideal value for this parameter is dictated by the hardware 47 dB for Range SDR1 This database parameter is static but the rxgain command can modify the receiver gain in real time OpenBTS gt rxgain 52 current RX gain is 47 dB new RX gain is 52 dB C 24 sendsimple and sendsms Commands Both of these commands send a text message via SMS to a given MS addressed by IMSI appearing to originate from a specified source address sendsimple lt IMSI gt lt sourceAddress gt lt messa
35. PAGING REQ gt 4 CHAN REO SETUP lt CALL CONFIRMED GA Status 183 Progress A Status 182 Ringing CONNECT a Status 200 OK lt lt ee RTP traffic ee gt lt e GSMtraffic gt Figure 6 3 A GSM SIP mobile terminated call VEA normal case 6 6 BACKHAUL CAPACITY CONSIDERATIONS 47 SIP Switch OpenBTS Handset CHAN REO IMMED ASSIGN lt CMSVC REQ CM SVC ACCEPT SETUP lt INVITE CALL PROCEEDING may Status 100 Trying j Status 182 Ringing gt Status 200 OK gt 4 e RIP traffic ee gt lt eee GSM traffic eee gt Figure 6 4 A GSM SIP mobile originated call VEA normal case 6 6 1 Available Codecs Currently OpenBTS only supports the GSM full rate codec GSM FR a 13 kbit sec codec with good speech quality This codec is also supported by Asterisk and has a moderate level of support among commercial VolP carriers The other codecs supported by Asterisk and of potential interest to OpenBTS operators are e G 711 a law or mu law This 64 kbit sec codec offers very good speech quality and is the most widely used in the PSTN and supported by nearly all VoIP carriers e G 729 This is an 8 kbit sec codec with fair speech quality and reasonably well supported by VoIP carriers The main drawbacks of G 729 are high computational complexity and a licensing fee of about 10 line year e Sp
36. PUBLIC LICENSE Version 1 February 1989 Copyright C 1989 Free Software Foundation Inc 51 Franklin St Fifth Floor Boston MA 02110 1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Preamble The license agreements of most software companies try to keep users at the mercy of those companies By contrast our General Public License is intended to guarantee your freedom to share and change free software to make sure the software is free for all its users The General Public License applies to the Free Software Foundation s software and to any other program whose authors commit to using it You can use it for your programs too 140 APPENDIX G FOSS LICENSES When we speak of free software we are referring to freedom not price Specifically the General Public License is designed to make sure that you have the freedom to give away or sell copies of free software that you receive source code or can get it if you want it that you can change the software or use pieces of it in new free programs and that you know you can do these things To protect your rights we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights These restrictions translate to certain responsibilities for you if you distribute copies of the software or if you modify it For example if you distribute copies of a such a program
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39. a GSM mobile switching center MSC In the standard OpenBTS deployment the default VoIP switch is Asterisk 11 The key concept in understanding OpenBTS SIP integration is that each GSM MS in communication with the BTS unit appears to the VoIP network as a SIP endpoint with the username IMSIxxxxxxxxxxxxxxx where XXXXXXXXXXXXXXX is a 14 or 15 digit IMSI from the MS s SIM The IP address of a SIP user is the IP address of its serving BTS OpenBTS itself is invisible to the VoIP network It is simply a conduit for the MSs 6 1 Subscriber Registry Commercial configurations of the OpenBTS Application Suite use a so called real time Asterisk configuration where Asterisk depends on an external sqlite3 database for its SIP registry and parts of its dialplan In OpenBTS the registry database is a part of an application called SIPAuthServe referred to as the Subscriber Registry The Subscriber Registry database is an Asterisk SIP registry following the standard sip_buddies format with the following fields added username varchar 80 this is the original SIP username but will be IMSI in OpenBTS WhiteListFlag timestamp not null default 0 true if MS is white listed WhiteListCode varchar 8 not null default 0 white listing access code rand varchar 33 default cached authentication token sres varchar 33 default cached authentication token ki varchar 33 default Ki the SIM secre
40. and 4 sec are reserved for GSM use TBF initiation using CCCH involves a significant delay that increases with the number of pending CCCH requests and therefore with the number of simultaneous users When the delay in TBF initiation gets too long the MS device gives up and may retry or simply report a loss of internet service to higher layers Therefore when CCCH congestion exceeds a threshold controlled by GSM CCCH AGCH QMax there is no longer any point in OpenBTS attempting to send the message and instead OpenBTS discards the message and logs a message at the CRITICAL or ALERT level The GSM CCCH AGCH QMax config parameter should not normally be changed by the operator as its value is determined by fixed delays in the GSM specification interacting with the intrinsic bandwidth of the OpenBTS CCCH channel Channel Congestion To maximize GPRS bandwidth the MS must be granted adjacent PhCH meaning the operator must set the GSM Channels parameters so that adjacent channels would be allocated for GPRS which simply means they must have values greater than one If all channels are in use OpenBTS starts issuing RLC is Radio Link Control the layer 2 part of GPRS Similar to LAPDn it provides reliable segmentation and reassembly across the physical channel The slowest encoding type CS 1 uses a rate 1 2 convolutional encoder The fastest type CS 4 uses no convolutional encoding CS 2 and CS 3 are intermediate rates based
41. and Audience 0 ee ee 8 1 2 License and Copyright s scere e Ree He eK A AAA Ge Re 8 1 3 Disclaimers e a o a AA RR a ah ee RR A 8 1 3 1 Warranty eoe cs iaoe o a oea kw a A E eee we eee E a 8 1 3 2 Arcila eee 20 reido dd ds 8 1 33 Patent LINS e iei kona a a a a A A e 8 1 3 4 Trademarks e a a A a E R Aa O a a a E a E i a 9 1 3 5 Telecom and Radio Spectrum Laws si ie nee tae a e E e a e A e a 9 1 36 FOSS License Compliance 243 e aa g a a 9 1 4 Source Code Availability aa ee 10 1 5 Abbreviations lt lt lt lt lt 4 040 a d oaao a a E ba a 11 MG References sica o o E td Ae eas de a Geet A Fe ely SEAE gt BR 12 1 6 1 References to ETSI Documents 12 16 2 ETSI 3GPP osos sr do E a aara ls Rae dle rancio be eS 12 103 IETF meys atoe ar a ob aa aaa S 12 1 7 Contact Information amp Support mea 13 LTL Direct Contacta a a a a a ee eS es 13 1 1 2 Online Resources ica aa e a O E Re EAS ed 13 The OpenBTS Release 4 0 Public is distributed publicly under the AGPLv3 license The OpenBTS Release 4 0 Commercial is distributed only to commercial customers normally under a binary license The commercial release provides the following improvements over the public release e Prioritization of emergency calls and IMS compliant emergency call headers e All applications in the OpenBTS application suite are configured as upstart services They start during
42. application type sudo stop openbts sudo start openbts Note This behavior is an enhancement over the previous versions of OpenBTS The runloop sh script is no longer in place 3 3 OpenBTS Command Line Interface CLI The OpenBTS console application is called the command line interface or CLI The CLI allows you to monitor system status and change many operating parameters of OpenBTS and the Transceiver in real time 3 3 1 Starting and Stopping the CLI Its executable is located at OpenBTS OpenBTSCLI on the file system To launch the CLI log into your access point via ssh and type on the Unix command line 3 3 OPENBTS COMMAND LINE INTERFACE CLI 21 OpenBTS OpenBTSCLI In order for the CLI to run OpenBTS application must also be running Once the CLI launches you will see the welcome notice and the OpenBTS command prompt OpenBTS Command Line Interface CLI utility Copyright 2012 2014 Range Networks Inc Licensed under GPLv2 Includes libreadline GPLv2 Connecting to 127 0 0 1 49300 Remote Interface Ready Type help to see commands version for version information notices for licensing information quit to exit console interface OpenBTS gt To exit the CLI type the quit command and press Enter Doing so does not stop the OpenBTS application The CLI at this time does not have a command to stop OpenBTS but it can restart OpenBTS with the shutdown command Once the OpenBTS appli
43. are sacrificed for additional SDCCH capacity Finally note that the numbers given for supportable idle MSs are much larger than the subscriber populations given in Table A 1 registration load should be a non issue for speech oriented networks A 2 Text Messaging SMS GSM text messaging short message service or SMS is a service akin to e mail Users can send and receive 140 byte messages allowing up to 160 characters using the SMS 7 bit alphabet Addresses can be ISDN private network E 164 or e mail SMS is a store and forward medium and can be held for minutes hours or even days if the receiving party is not available Text messaging also uses reliable channels like the SDCCH with frame retransmission and acknowledgement in L2 making it tolerant of frame erasure rates in excess of 50 These properties make SMS a usable medium over much larger coverage areas than speech in areas where coverage is spotty or weak and where speech quality would be too poor and calls would disconnect too frequently to be useful A 2 TEXT MESSAGING SMS 73 A 2 1 Internet Messaging Protocols For OpenBTS to handle SMS in a manner consistent with its design goals the GSM SMS protocol must be translated to and from some open protocol from the internet world There are many such protocols but few are well suited to SMS The Session Problem Most messaging protocols in the IETF IP world like XMPP are built around the notion of a connect
44. by us 2 sent by someone else AUTH INTEGER DEFAULT O Authorization result 0 unauthorized AUTH_EXPIRY INTEGER DEFAULT O Absolute time seconds when authorization expires or 0 for single use REJECT_CODE INTEGER DEFAULT O Reject code or 0 if authorized TMSI_ASSIGNED INTEGER DEFAULT 0 Set when the TMSI has been successfully assigned to the MS ie the MS knows it Set when the P TMSI has been successfully assigned to the MS by PTMSI_ASSIGNED INTEGER DEFAULT 0 In order for this scheme to work correctly each BTS in a multi BTS network must have a unique location area code 30 CHAPTER 4 OPENBTS DATA TABLES AND STRUCTURES the SGSN ie the MS knows it 4 4 Transaction Table OpenBTS reports in progress calls and SMS transfers to an external sqlite3 database table called Transac tion table with the default location at var run OpenBTS TransactionTable db which is set in the Control Reporting TransactionTable configuration parameter This table is treated as write only by OpenBTS but should be treated as read only by other applications The SQL schema is CREATE TABLE 1F NOT EXISTS TRANSACTION_TABLE ID INTEGER PRIMARY KEY internal transaction ID CHANNEL TEXT DEFAULT NULL channel description string cross refs CHANNEL_TABLE CREATED INTEGER NOT NULL Unix time of record creation CHANGED INTEGER NOT NULL Unix time of last state change TYPE TEXT transaction type SUBSCRIB
45. change it By contrast the GNU General Public Licenses are intended to guarantee your freedom to share and change free software to make sure the software is free for all its users This license the Lesser General Public License applies to some specially designated software packages typically libraries of the Free Software Foundation and other authors who decide to use it You can use it too but we suggest you first think carefully about whether this license or the ordinary General Public License is the better strategy to use in any particular case based on the explanations below When we speak of free software we are referring to freedom of use not price Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software and charge for this service if you wish that you receive source code or can get it if you want it that you can change the software and use pieces of it in new free programs and that you are informed that you can do these things To protect your rights we need to make restrictions that forbid distributors to deny you these rights or to ask you to surrender these rights These restrictions translate to certain responsibilities for you if you distribute copies of the library or if you modify it G 5 GNU LESSER GENERAL PUBLIC LICENSE V 2 1 167 For example if you distribute copies of the library whether gratis or for a fee you must give the recipients all the r
46. collective works based on the Program In addition mere aggregation of another work not based on the Program with the Program or with a work based on the Program on a volume of a storage or distribution medium does not bring the other work under the scope of this License 3 You may copy and distribute the Program or a work based on it under Section 2 in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following a Accompany it with the complete corresponding machine readable source code which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange or b Accompany it with a written offer valid for at least three years to give any third party for a charge no more than your cost of physically performing source distribution a complete machine readable copy of the corresponding source code to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange or 148 APPENDIX G FOSS LICENSES c Accompany it with the information you received as to the offer to distribute corresponding source code This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer in accord with Subsection b above The source code for a work means the preferred form of the work for making modif
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48. granted herein 7 The Free Software Foundation may publish revised and or new versions of the General Public License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If the Program specifies a version number of the license which applies to it and any later version you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation If the Program does not specify a version number of the license you may choose any version ever published by the Free Software Foundation 8 If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different write to the author G 2 GNU GENERAL PUBLIC LICENSE V 1 143 to ask for permission For software which is copyrighted by the Free Software Foundation write to the Free Software Foundation we sometimes make exceptions for this Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally NO WARRANTY 9 BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE THERE IS NO WARRANTY FOR THE PROGRAM TO THE EXTENT PERMITTED BY APPLICABLE LAW EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND OR OTHER PART
49. is stored in e SIP Proxy Registration This parameter is set to the IP address and port of SIPAuthServe 6 1 5 Intercepting Authentication For some applications it may be useful for a network operator to take control of authentication decisions to apply rules that are more complex than simply authenticating individual users against the contents of the sip_buddies table For example a carrier may be implementing complex whitelist and blacklist operations OpenBTS developers could try to predict these various custom applications and create a whole new family of configuration parameters A better approach though is for operators to insert their own custom software into the authentication process to short circuit the normal authentication mechanism or to modify the AlPAuthServe application which is provided to Range customers under a GPL license On the SIP interface the operator s custom software is a very simple SIP proxy that accepts and processes the SIP REGISTER method The OpenBTS SIP Proxy Registration parameter points to this custom SIP proxy and the custom SIP proxy relays SIP requests and responses as needed between OpenBTS and the Subscriber Registry 6 2 Provisioning New Subscribers Provisioning is a process of creating new subscriber accounts OpenBTS subscribers are provisioned like any other SIP subscribers in an Asterisk system with the following constraints e The SIP username is always IMSI
50. local copy of the log on the BTS unit itself possibly at a different logging level E 5 2 Configuring the Monitoring Station At the remote host where the log events are to be received there is a corresponding rsyslogd instance configured to listen on the given port The network reported will be further processed according to the remote system s rsyslogd configuration The configuration lines are For TCP on port 514 InputServerRun 514 For UDP on port 514 UDPServerRun 514 This monitoring station should also have a etc rsyslog d OpenBTS conf file containing the line local7 var log 0penBTS log to route OpenBTS related message to var log OpenBTS log giving a unified log of all of the activity in the OpenBTS network E 5 3 Example Using multi BTS example network from Section E 2 we can configure the central server at 192 168 1 20 to also act as a central logging monitor over TCP IP In this example the central facility will log events at or above the CRIT level On every BTS unit add this line to etc rsyslog d OpenBTS conf local7 crit 192 168 1 20 514 128 APPENDIX E MULTI BTS NETWORKS Then execute this line on each unit to restart rsyslogd sudo service rsyslog restart On the central server at 192 168 1 20 add this line to etc rsyslogd conf For TCP on port 514 InputServerRun 514 Add this line to etc rsyslog d OpenBTS conf local7 var log OpenBTS log Then execute this line to resta
51. long as the following conditions are aheared to Copyright remains the authors and as such any Copyright notices in the code are not to be removed Redistribution and use in source and binary forms with or without modification are permitted provided that the following conditions are met 1 Redistributions of source code must retain the copyright notice this list of conditions and the following disclaimer 2 Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution THIS SOFTWARE IS PROVIDED AS IS AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE G 7 2 BSD License on Sparkline plug in Copyright c 2012 Splunk Inc All rights reserved Redistribution and use in so
52. not hand over stop 2 If the RSSI of the strongest neighbor exceeds the RSSI of the serving BTS by more than the value given in GSM Handover ThresholdDelta in dB initiate a handover to the strongest neighbor Initiating Handover The actual handover transaction starts when the serving BTS BTS1 sends the RPP REQ HANDOVER message to the selected neighbor BTS2 This message carries the entire call state in the GSM SIP and RTP domains BTS2 responds with RPP RSP HANDOVER This response normally indicates acceptance of the inbound handover by BTS2 and includes a description of the radio channel to which the handset will be transferred If BTS2 cannot accept the handover usually due to congestion this message will contain an error cause code and a hold off time during which additional handovers should not be requested from BTS2 Moving to the New Radio Channel At this point in the protocol BTS2 has a copy of the complete call state and BTS1 has a description of the radio channel on BTS2 to which the call is to be transferred BTS1 now sends the handset a GSM Handover Notice that in the idle mode it is the handset s decision to move to a new cell while during an active call the decision to move the handset to a new cell is made by the BTS unit 126 APPENDIX E MULTI BTS NETWORKS Command containing a description of the radio channel on BTS2 Meanwhile BTS2 creates a clone of the call s transaction record in its ow
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58. refers to a function or data to be supplied by an Application that uses the facility other than as an argument passed when the facility is invoked then you may convey a copy of the modified version a under this License provided that you make a good faith effort to ensure that in the event an Application does not supply the function or data the facility still operates and performs whatever part of its purpose remains meaningful or b under the GNU GPL with none of the additional permissions of this License applicable to that copy 3 Object Code Incorporating Material from Library Header Files The object code form of an Application may incorporate material from a header file that is part of the Library You may convey such object code under terms of your choice provided that if the incorporated material is not limited to numerical parameters data structure layouts and accessors or small macros inline functions and templates ten or fewer lines in length you do both of the following a Give prominent notice with each copy of the object code that the Library is used in it and that the Library and its use are covered by this License b Accompany the object code with a copy of the GNU GPL and this license document 4 Combined Works You may convey a Combined Work under terms of your choice that taken together effectively do not restrict modification of the portions of the Library contained in the Combined Work and reverse engineeri
59. service The return address for this message the OpenBTS configuration parameter Control LUR OpenRegistration ShortCode must match the address of the register short code function defined in the SMQueue configuration pa rameter SC Register Code 3 The user responds to the text message with a telephone number 4 The SMS response is transferred from the MS to OpenBTS to SMQueue where it is delivered to the register short code function 5 The register short code function updates the Subscriber Registry to provision the new user 6 The register short code function generates an SMS confirmation or error message to the user delivered by SMQueue to OpenBTS to the MS 6 2 2 Whitelisting OpenBTS provides a whitelisting system based on SMS This mechanism can be used to restrict access to the cellular network to a trusted group even when using automatic provisioning When a new subscriber entry is created in the Subscriber Registry it can be designated as on or off the while list If an MS is on the whitelist it will register and authenticate normally If an MS is not on the whitelist it receives a text message containing an access code but is otherwise denied service The new MS can now be added to the whitelist and granted service through this process 1 Any other MS that is already on the whitelist and has service can send the new MS s access code to a short code application Section 7 3 in SMQu
60. single ARFCN is called a physical channel PhCH and referred to as Cn Tm where n is a carrier index and m is a timeslot index 0 7 Each timeslot is occupied by a radio burst with a guard interval two payload fields tail bits and a midamble or training sequence The lengths of these fields vary with the burst type but the total burst length is always 156 25 symbol periods The most commonly used burst is the Normal Burst NB There are several other burst formats though Bursts that require higher processing gain for signal acquisition have longer midambles The random access burst RACH has an extended guard period to allow it to be transmitted with incomplete timing acquisition Burst formats are described in GSM 05 02 Section 5 2 Multiplexing and Timing Each physical channel is time multiplexed into multiple logical channels according to the rules of GSM 05 02 Traffic channel multiplexing follows a 26 frame 0 12 second cycle called a mul tiframe Control channels follow a 51 frame multiframe cycle The COTO physical channel carries the SCH which encodes the timing state of the BTS to facilitate synchronization to the TDMA pattern GSM timing is driven by the serving BTS through the SCH and FCCH All clocks in the MS including the symbol clock and local oscillator are slaved to signals received from the BTS as described in GSM 05 10 BTSs in the GSM network can be asynchronous so that each BTS can run an independent clock
61. sipauthserve and ad vanced tabs in the Configuration panel in commercial installations or by editing the configuration table with sqlite3 the only option currently applicable to the public release 6 1 2 Accessing the Subscriber Registry Commercial Release Only In the commercial release the Subscriber Registry database can be accessed using OpenRANUI web interface Select the Databases panel pick SIP buddies from the list of available databases and click on re load to print the raw data OpenRANUI is also used to manage subscribers See Section 6 2 1 for details 6 1 3 SIPAuthServe Authentication Interface SIPAuthServe supports direct SIP authentication on the Subscriber Registry performing a transaction modeled after IMS authentication and SIP digest authentication Figure 6 2 but using e the RAND value as the nonce e an operator specified A3 A8 instead of MD5 as the hash function SIPAuthServe supports two forms of RAND SRES authentication on each interface e Full Authentication This is the standard A3 authentication used when Ki is known in the registry OpenBTS includes support for COMP128v1 as A3 The registry invokes the A3 algorithm as an external Unix application with a standard calling interface making it easy to add support for other A3 algorithms if implementations are available e Cached Authentication This type of authentication uses the same protocol steps on Um as
62. that are allowed to attach Control LUR UnprovisionedRejectCause Reject cause for location updating failures for unprovi sioned phones that is the IMSI was not found in the Registrar database The SIP result code from the Registrar in this case is 401 Reject causes come from GSM 04 08 10 5 3 6 Reject cause 0x02 or 0x04 is usually the right one Control Reporting PhysStatusTable File path for channel status reporting database Control Reporting StatsTable File path for statistics reporting database Control Reporting TMSITable File path for TMSITable database Control Reporting TransactionTable File path for transaction table database Control SMSCB Table File path for SMSCB scheduling database By default this feature is disabled To enable specify a file path for the database e g var run OpenBTS SMSCB db To disable again execute unconfig Control SMSCB Table Control TMSITable MaxAge Maximum allowed age in hours for a TMSI entry in the TMSITable This is not the authorization registration expiry period this is how long the BTS remembers assigned TMSls Currently old entries are only discarded at startup Control VEA Use very early assignment for speech call establishment See GSM 04 08 Section 7 3 2 for a detailed explanation of assignment types If VEA is selected GSM CellSelection NECI should be set to 1 See GSM 04 08 Sections 9 1 8 and 10 5 2 4 for an explanation of the NECI bit Note that som
63. the BTS and allowed virtually unlimited access to IP protocols a malicious device could potentially gain undesired access to the BTS itself To prevent this the GGSN prevents any GPRS enabled device from talking to any other GPRS enabled device in the same BTS or to the BTS itself and optionally to any private IP address by implementing the firewall The firewall is controlled by the GGSN Firewall Enable configuration option and is enabled by default If GGSN internal firewall is disabled a GPRS enabled device can access the BTS itself which poses a serious security risk It is critical to add routing rules on the Linux system running the BTS to prevent IP addresses in the range allocated to the GPRS enabled devices from accessing the BTS unit itself Note It is also important that GPRS systems use strong passwords on the BTS units and to avoid the creation of extraneous user accounts A 4 GENERAL PACKET RADIO SERVICE GPRS 79 Additionally depending on the internet topology where the BTS is connected it is also possible that these GPRS enabled devices are entering the private IP network to which the BTS unit is connected For a sim ple network topology where you have other computers or base stations using private IP addresses for example 192 168 xxx yyy behind a single firewall router this access can be prevented by setting the GPRS Firewall Enable parameter to 2 which attempts to prevent the GPRS enabled devices from access
64. the CCCH with an Immediate Assignment Reject message as defined in GSM 04 08 Section 9 1 20 This message carries a value T3122 that dictates how long the rejected MS must wait before making another access attempt Emergency call attempts are not subject to T3122 waiting OpenBTS implements an exponential back off algorithm that causes T3122 to grow exponentially whenever channel exhaustion occurs The bounds for T3122 are set with the configuration parameters GSM Timer T3122Max and GSM Timer T3122Min given in milliseconds To disable the exponential back off set these two bounds to the same value T3122 back off is connected to downlink power adaptation described in Section 5 1 5 1 2 Physical Measurements Downlink Path Loss in dB can be estimated as P P where P is the RSSI in dBm and P is the output power of the BTS in dBm For example if the BTS output is 10 Watts 40 dBm and the RSSI is reported as 90 dBm then the total path loss is 90 40 130 dB This total loss includes all cable losses and antenna gains Handset Distance Round trip propagation delay is directly proportional to handset s distance from the BTS That distance is approximately 535 meters per symbol period of round tip delay The round trip delay reported in the Channel table is in two parts e Timing Advance This is a clock offset inside the handset controlled by the BTS to compensate for propagation delay It is in integer symbol period
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66. to SMQueue SMQueue responds with OK and then OpenBTS responds to the MS with RP ACK 3Strictly speaking page mode message transfers are not transactions in SIP since they are not contained within an INVITE BYE session However these transfers are transactions inside of OpenBTS and will be referred to as transactions throughout the OpenBTS documentation 76APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS smqueue OpenBTS MS CHAN REQ ASSIGNMENT m CM SVC REO CM SVC ACCEPT m CP DATA RP ACK 35 gt Figure A 3 Mobile originated SMS transfer with no parallel call normal case A 3 Short Message Service Cell Broadcast SMSCB Short Message Service Cell Broadcast SMSCB is a low rate data service defined in GSM Specifications 03 41 and 04 21 It was originally intended for low rate information services such as traffic reports and sports scores While the name suggests that this broadcast service is somehow closely related to SMS the truth is that the two are completely independent of each other Nearly all GSM MSs are capable of receiving and displaying SMSCB messages although most MSs are not configured to do so by default Note Currently OpenBTS supports only ASCII for SMSCB payloads A 3 1 Cell Broadcast Channel CBCH The Cell Broadcast Channel CBCH defined in GSM Specification 05 02 Section 6 5 4 is essentially an SDCCH that has been set aside to the SMS
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68. writing and signed by the party to be charged with such waiver or consent This License constitutes the entire agreement between the parties with respect to the Work licensed here There are no understandings agreements or representations with respect to the Work not specified here Licensor shall not be bound by any additional provisions that may appear in any communication from You This License may not be modified without the mutual written agreement of the Licensor and You The rights granted under and the subject matter referenced in this License were drafted utilizing the terminology of the Berne Convention for the Protection of Literary and Artistic Works as amended on September 28 1979 the Rome Convention of 1961 the WIPO Copyright Treaty of 1996 the WIPO Performances and Phonograms Treaty of 1996 and the Universal Copyright Convention as revised on July 24 1971 These rights and subject matter take effect in the relevant jurisdiction in which the License terms are sought to be enforced according to the corresponding provisions of the implementation of those treaty provisions in the applicable national law If the standard suite of rights granted under applicable copyright law includes additional rights not granted under this License such additional rights are deemed to be included in the License this License is not intended to restrict the license of any rights under applicable law G 2 GNU General Public License v 1 GNU GENERAL
69. 04 07 and 04 08 and has three sublayers A subscriber terminal must establish a connection in each sublayer before accessing the next higher sublayer e Radio Resource RR This sublayer manages the assignment and release of logical channels on the radio link It is normally terminated in the BSC although in OpenBTS RR is terminated locally in the OpenBTS stack e Mobility Management MM This sublayer authenticates users and tracks their movements from cell to cell OpenBTS translates MM transactions into corresponding SIP transactions and uses the Asterisk SIP registry to perform MM functions e Call Control CC This sublayer connects telephone calls and is taken directly from ITU T Q 931 GSM 04 08 Annex E provides a table of corresponding paragraphs in GSM 04 08 and ITU T Q 931 along with a summary of differences between the two In OpenBTS CC transactions are translated to corresponding SIP transactions and processed in an external SIP switch or PBX like Asterisk The access order is RR MM CC The release order is the reverse of that A 1 2 Um logical channels Um logical channel types are outlined in GSM 04 03 Broadly speaking non GRPS Um logical channels fall into three categories traffic channels dedicated control channels and non dedicated control channels Traffic channels TCH These point to point channels correspond to the ISDN B channel and are referred to as Bm channels Traffic channels use 8 burst diagonal interl
70. 3 of the GNU General Public License G 6 GNU LESSER GENERAL PUBLIC LICENSE V 3 177 The Library refers to a covered work governed by this License other than an Application or a Combined Work as defined below An Application is any work that makes use of an interface provided by the Library but which is not otherwise based on the Library Defining a subclass of a class defined by the Library is deemed a mode of using an interface provided by the Library A Combined Work is a work produced by combining or linking an Application with the Library The particular version of the Library with which the Combined Work was made is also called the Linked Version The Minimal Corresponding Source for a Combined Work means the Corresponding Source for the Combined Work excluding any source code for portions of the Combined Work that considered in isolation are based on the Application and not on the Linked Version The Corresponding Application Code for a Combined Work means the object code and or source code for the Application including any data and utility programs needed for reproducing the Combined Work from the Application but excluding the System Libraries of the Combined Work 1 Exception to Section 3 of the GNU GPL You may convey a covered work under sections 3 and 4 of this License without being bound by section 3 of the GNU GPL 2 Conveying Modified Versions If you modify a copy of the Library and in your modifications a facility
71. 4 should be avoided GSM Radio PowerManager MaxAttenDB Maximum transmitter attenuation level in dB wrt full scale on the D A output This sets the minimum power output level in the output power control loop GSM Radio PowerManager MinAttenDB Minimum transmitter attenuation level in dB wrt full scale on the D A output This sets the maximum power output level in the output power control loop GSM Radio RSSITarget Target uplink RSSI for MS power control loop in dB wrt to A D full scale Should be 6 10 dB above the noise floor GSM ShowCountry Tell the MS to show the country name based on the MCC GSM SpeechBuffer Size of speech buffer in milliseconds If set to 0 no RTP speech buffer is used If set to 1 the RTP speech buffer size is determined adaptively Any other value sets the speech buffer size The speech buffer is needed to overcome jitter caused by natural variation in the internet traffic delay Note that speech is noticeably delayed by this amount so we want to keep it as low as possible and still have reasonably reliable delivery The specified delay is in addition to the intrinsic buffering inside OpenBTS This value is used only at the start of a call changing it does not affect on going calls 92 APPENDIX B CONFIGURATION PARAMETERS GSM Timer Handover Holdoff Handover will not be permitted until this time has elapsed after an initial channel seizure or handover GSM Timer T3212 Registration t
72. 40 e GSM Neighbors 192 168 1 31 192 168 1 32 e GSM Identity BCC 0 e GSM Identity LAC 1000 e SIP Local IP 192 168 1 30 For unit B on ARFCN 42 at IP 192 168 1 31 e GSM Radio CO 42 e GSM Neighbors 192 168 1 30 192 168 1 32 e GSM Identity BCC 1 e GSM Identity LAC 1001 e SIP Local IP 192 168 1 31 For unit C on ARFCN 44 at IP 192 168 1 32 e GSM Radio CO 44 e GSM Neighbors 192 168 1 30 192 168 1 31 e GSM Identity BCC 2 e GSM Identity LAC 1002 122 APPENDIX E MULTI BTS NETWORKS e SIP Local IP 192 168 1 32 Note the following about the configurations e SIP Proxy are the same on all units pointing all of the BTS units to a common server e SIP Local IP is the IP address of each BTS as seen by the Asterisk server e GSM Radio CO0 is different on each BTS e GSM Neighbors lists all of the other BTS IP addresses on each BTS e GSM Identity NCC is the same on all units e GSM Identity BCC is different on all units e GSM Identity LAC is different on all units e GSM CellSelection NCCsPermitted is 1 because GSM Identity NCC is 0 so the NCC mask selects just the NCC for this network e GSM CellSelection CELL RESELECT HYSTERESIS is 3 giving a hysteresis of 6 dB so whenever a neigh boring cell is measured to be more than 6 dB stronger than the serving cell the MS will recamp to the neighbor which will trigger a registration in the Asterisk server at the new cell s IP address E 3 Example of Mobility Configuration
73. 5 A 1 A 2 A 3 E 1 E 2 ES Components of the OpenBTS application suite and their communication channels as installed in each access point Sharp cornered boxes are hardware components Round cornered boxes are software components aooo e ee 17 Two access points with unit 1 providing servers for both 2004 18 GSM location update mapped to a SIP REGISTER non authenticating case 45 GSM location update mapped to a SIP REGISTER with authentication 46 A GSM SIP mobile terminated call VEA normal case 46 A GSM SIP mobile originated call VEA normal case ee 47 Paired Asterisk servers for AX trunking in satellite based applications 0 49 Layers and channels of the Um interface This figure shows the basic logical channel types in a subset of a typical configuration osoo oea e e a 65 Mobile terminated SMS transfer with no parallel call normal case o oo a 75 Mobile originated SMS transfer with no parallel call normal case 76 A three BTS network with a COMMON server o oo e e 120 Improved mobility architecture For simplicity only two cell sites are shown each with three units 123 GSM RPP and SIP signaling for OpenBTS handover In this example a call that originated on BTS1 is handed over to BTS2 The call is between the MS and the remote party Signaling between BTS units and MS is GSM Sig
74. A A we ao 103 audit C mmand sir shew oi ie aa a ie a a E a 103 calls Command 2 20k pa bes Se A A AR e eS 103 cellid Command 20 036 socs ee A a a ee ee 104 chans Command ia sosoran a 245 SP ee e ORE EO ae a a E 104 config Commands io s csa a ee aos odia Re AA ee e 105 devconfig Command oa s 6 ca pia mea aa a a n a ew a 106 endcall Command s su 800 so a ea eR A e we 106 freqcorr Comma d io soe Se a a a Da A ee a es 107 gprs Command se roepe A AA A 107 CAO L gprs list Subeommand 44444008 ridad a dd 107 C 10 2 Other gprs Subcommands gt s ss ss ss am seda RAR risa 108 handover Command i s sasa a a E ee a E E 108 help Command ss siem eee a a Sah A OS BS Gea e 108 load Command 22424 2 2 eee Dee Pee eee ORE Ee eee e 108 memstat Command s sa s oro e aa Gee aoa aoa afa ee ee ee a 109 neighbors Command lt s e reisiem re RES RR Ee ee eS 109 noise Command sor e soewe soe a we a a Dae a eee a 109 notices Command 2 22 00 ers a A aa 109 page Command s sss d 640 e adaon a a A ee ew Oe 109 power Command oscar Be ake a Ve AEG a ot Boe ea 110 ravcontig Command aose e es kee Se ee eR o A ee Re ee SX 110 reppericd COMME a A a ee a ee Re 111 rmcontig Command ig aaa a eee RARER RR a RS 111 yxgain Command si sessa 2 ee 111 sendsimple and sendsms Commands 000 002 112
75. ABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU Lesser General Public License for more details You should have received a copy of the GNU Lesser General Public License along with this library if not write to the Free Software Foundation Inc 51 Franklin Street Fifth Floor Boston MA 02110 1301 USA Also add information on how to contact you by electronic and paper mail You should also get your employer if you work as a programmer or your school if any to sign a copyright disclaimer for the library if necessary Here is a sample alter the names Yoyodyne Inc hereby disclaims all copyright interest in the library Frob a library for tweaking knobs written by James Random Hacker lt signature of Ty Coon gt 1 April 1990 Ty Coon President of Vice That s all there is to it G 6 GNU Lesser General Public License v 3 GNU LESSER GENERAL PUBLIC LICENSE Version 3 29 June 2007 Copyright c 2007 Free Software Foundation Inc jhttp fsf org i Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed This version of the GNU Lesser General Public License incorporates the terms and conditions of version 3 of the GNU General Public License supplemented by the additional permissions listed below 0 Additional Definitions As used herein this License refers to version 3 of the GNU Lesser General Public License and the GNU GPL refers to version
76. CB payload If SMSCB is enabled one SDCCH must be sacrificed to provide the bandwidth There are constraints on the placement of the CBCH in terms of carrier index and timeslot To meet these constraints either the COTO must be Combination V or GSM Channels C1sFirst must be left undefined an empty string The CBCH has a maximum data rate of 97 7 bytes per second Each message is carried in a fixed length 88 byte frame having 6 header bytes and an 82 byte payload field The service is capable of delivering roughly one such message every second A 3 2 Scheduling Messages for Delivery Specification 03 41 describes a hierarchy of servers to distribute content for the SMSCB service and a protocol in L3 for delivery of SMSCB content to the BTS A 4 GENERAL PACKET RADIO SERVICE GPRS T7 OpenBTS does not follow this model Instead OpenBTS takes messages for delivery from an sqlite3 database table at a path specified in the Control SMSCB Table parameter The schema is CREATE TABLE IF NOT EXISTS SMSCB GS INTEGER NOT NULL See GSM 03 41 9 3 2 1 MESSAGE_CODE INTEGER NOT NULL See GSM 03 41 9 3 2 1 UPDATE_NUMBER INTEGER NOT NULL See GSM 03 41 9 3 2 1 MSGID INTEGER NOT NULL See GSM 03 41 9 3 2 2 LANGUAGE_CODE INTEGER NOT NULL See GSM 03 41 9 3 2 3 and GSM 03 38 MESSAGE TEXT NOT NULL the actual message text ASCII SEND_TIME INTEGER DEFAULT 0 Unix time when this message was last sent SEND_COUNT INTEGER DEFA
77. Click on add subscriber button and provide the subscriber s name phone number and IMSI Because there is no roaming relationship the number assigned to the SIM in the OpenBTS network is indepen dent of the number assigned in any other cellular network although it may be convenient for the two numbers to be the same Note It is possible to provision a handset with no telephone number at all in which case the provisioned MS cannot accept inbound calls but can still place outbound calls Interactive via SMS The SMQueue SMS server and the SIPAuthServe can be used together to provide an interactive autoprovisioning system based on SMS The configuration parameters are e In SMQueue The SC Register parameter set See Section 7 3 1 e In OpenBTS Control LUR OpenRegistration parameter must be defined to accept the intended handsets and the Control LUR OpenRegistration parameters must be defined See Section 6 2 3 The autoprovisioning process is 1 The MS attempts a location updating request Even though the MS is not provisioned the network will accept the request 40 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK 2 While the MS still has an open dedicated channel to OpenBTS OpenBTS sends it the open registration welcome message defined in Control LUR OpenRegistration Message This message is usually something like Please respond to this message with your telephone number to receive
78. Configuration of Handsets for OpenBTS GPRS 9 2 1 APN Settings OpenBTS GPRS does not enforce the use of any particular APN Access Point Name but at least one APN must be defined in the handset for it to use GPRS 9 2 2 Data Roaming If the MCC and MNC of your BTS unit do not match those of a user s SIM card it may be necessary to enable data roaming on the handset before it will attempt to use GPRS 9 3 Using CLI to Monitor and Control GPRS Two CLI commands used to monitor and control GPRS activity are gprs and sgsn The gprs command provides means to selectively start and stop GPRS service list channels in use by GPRS and set the debug level The full list of parameters is available in Appendix section C 10 The sgsn command allows to monitor and control SGSN GGSN sub system An overview of its parameters is provided in Appendix section C 25 Chapter 10 NodeManager 10 1 NodeManager API Interface aaa ee 58 101 1 Request KeyS o oe 22 e45 2656654 686244654 bb bbe ode O44 4 58 10 1 2 Response Codes a 59 10 1 3 Response Keys 59 10 2 Running NodeManager Queries 002 eee ee ee 60 HOLS Port Utilization s s acia ci e Ens o ai a eE Bee ae eee a 61 NodeManager is a management API allowing third party applications to manage the following components of OpenBTS Application Suite OpenBTS SIPAuthServe and SMQueue lt uses a JSON interface operated over a ZeroMQ REQ RE
79. ELL_RSSI INTEGER DEFAULT NULL RSSI measurement of the strongest neighbor Chapter 5 OpenBTS and the Transceiver 5 1 Downlink Power and Congestion Management asa sa aa 5 1 1 13122 Exponential Back Off 0 0 e 5 1 2 Physical Measurements 22 8688 47 al a a 5 2 Uplink Power and Timing Control o e 2 ee 521 Uplink Power Contralor spray A Rd 522 Uplink Timing Control ss mr s er aaa a AA e oe a a iaa a Please refer to Appendix section A 1 for in depth description of the OpenBTS implementation of GSM air interface Um including references to relevant GSM specifications 5 1 Downlink Power and Congestion Management OpenBTS can automatically adjust its downlink power to limit loads and prevent congestion This feature is especially useful for graceful power up in areas with very high subscriber density and load shedding in the event of sudden failure of a neighboring cell or even the failure of a nearby cell of a different operator This congestion management feature works in conjunction with the T3122 adaptation loop described in Section 5 1 1 The practical result of the automatic power adjustment is to limit the service area of the BTS to a population of nearby phones that it can actually serve The configuration parameters associated with this mechanism are e GSM Radio PowerManager TargetT3122 This is the acceptable value of T3122 that the power man
80. ER TEXT IMSI if known L3TI INTEGER GSM L3 transaction ID 8 if generated by MS SIP_CALLID TEXT SIP side call id tag SIP_PROXY TEXT SIP proxy IP CALLED TEXT called party number if known CALLING TEXT calling party number if known GSMSTATE TEXT current GSM Q 931 state SIPSTATE TEXT current SIP state The CHANNEL column uses the same encoding as the CN_TN_TYPE_AND_OFFSET column in the Channel Table and can by used to cross reference the two tables It is a channel description string of the form C lt n gt T lt n gt lt channelType gt lt subchannel Index gt For example e COT1 TCH F is a full rate traffic channel on timeslot 1 of the CO ARFCN and e COTO SDCCH 0 4 is the 0 SDCCH of 4 available on COTO 4 5 Channel Table OpenBTS reports real time physical status information for active dedicated channels to an external sqlite3 database table called Channel Table or PHYSTATUS The entry for a channel is updated every time a Measurement Report message is received on the channel s associated SACCH The table s default location 4 5 CHANNEL TABLE 31 is var run OpenBTS ChannelTable db which is set in the Control Reporting PhysStatusTable configuration parameter This table is treated as write only by OpenBTS but should be treated as read only by other applications The schema is CREATE TABLE IF NOT EXISTS PHYSTATUS CN_TN_TYPE_AND_OFFSET STRING PRIMARY KEY
81. ErrorB Second part of message sent during registration if the handset fails to register followed by the handset IMSI SC Register Msg TakenA First part of message sent during registration if the handset fails to register because the desired number is already taken followed by the attempted handset number SC Register Msg TakenB Second part of message sent during registration if the handset fails to register because the desired number is already taken SC Register Msg WelcomeA First part of message sent during registration if the handset registers successfully followed by the assigned handset number SC Register Msg WelcomeB Second part of message sent during registration if the handset registers successfully SC SMSC Code The SMSC entry point There is where OpenBTS sends SIP MESSAGES to SIP Default BTSPort The default BTS port to try when none is available SIP GlobalRelay ContentType The content type that the global relay expects SIP GlobalRelay IP IP address of global relay to send unresolvable messages to By default this is disabled To override specify an IP address To disable again use unconfig SIP GlobalRelay IP SIP GlobalRelay Port Port of global relay to send unresolvable messages to SIP GlobalRelay RelaxedVerify Relax relay verification by only using SIP Header SIP Timeout ACKedMessageResend Number of seconds to delay resending ACK messages 100 APPENDIX B CONF
82. IES PROVIDE THE PROGRAM AS IS WITHOUT WARRANTY OF ANY KIND EITHER EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU SHOULD THE PROGRAM PROVE DEFECTIVE YOU ASSUME THE COST OF ALL NECESSARY SERVICING REPAIR OR CORRECTION 10 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER OR ANY OTHER PARTY WHO MAY MODIFY AND OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE BE LIABLE TO YOU FOR DAMAGES INCLUDING ANY GENERAL SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES END OF TERMS AND CONDITIONS Appendix How to Apply These Terms to Your New Programs If you develop a new program and you want it to be of the greatest possible use to humanity the best way to achieve this is to make it free software which everyone can redistribute and change under these terms To do so attach the following notices to the program It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty a
83. IGURATION PARAMETERS e SIP Timeout MessageBounce Timeout in seconds between bounced message sending tries e SIP Timeout MessageResend Timeout in seconds between message sending tries e SIP myIP The internal IP address Usually 127 0 0 1 e SIP myIP2 The external IP address that is communciated to the SIP endpoints e SIP myPort The port that smqueue should bind to e SMS FakeSrcSMSC Use this to fill in L4 SMSC address in SMS delivery e SMS HTTPGateway Retries Maximum retries for HTTP gateway attempt e SMS HTTPGateway Timeout Timeout for HTTP gateway attempt in seconds e SMS HTTPGateway URL URL for HTTP API Used directly as a C format string with two e SMS MaxRetries Messages will only be attempted to be sent this many times before giving up and being dropped Set to 0 to allow infinite retries e SMS RateLimit Limit delivery rate to one message every X seconds Set to 0 to disable rate limiting e SubscriberRegistry A3A8 Path to the program that implements the A3 A8 algorithm e SubscriberRegistry Port Port used by the SIP Authentication Server NOTE In some older releases pre 2 8 1 this is called SIP myPort e SubscriberRegistry UpstreamServer URL of the subscriber registry HTTP interface on the up stream server By default this feature is disabled To enable specify a server URL eg http localhost cgi subre e SubscriberRegistry db The location of th
84. N OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND OR OTHER PARTIES PROVIDE THE PROGRAM AS IS WITHOUT WARRANTY OF ANY KIND EITHER EXPRESSED OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU SHOULD THE PROGRAM PROVE DEFECTIVE YOU ASSUME THE COST OF ALL NECESSARY SERVICING REPAIR OR CORRECTION 12 IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER OR ANY OTHER PARTY WHO MAY MODIFY AND OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE BE LIABLE TO YOU FOR DAMAGES INCLUDING ANY GENERAL SPECIAL INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program and you want it to be of the greatest possible use to the public the best way to achieve this is to make it free software which everyone can redistribute and change under these terms To do so attach the following notices to the program It is safest to attach them to the start of each source
85. OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE LIBRARY TO OPERATE WITH ANY OTHER SOFTWARE EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Libraries If you develop a new library and you want it to be of the greatest possible use to the public we recommend making it free software that everyone can redistribute and change You can do so by permitting redistribution under these terms or alternatively under the terms of the ordinary General Public License To apply these terms attach the following notices to the library It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty and each file should have at least the 176 APPENDIX G FOSS LICENSES copyright line and a pointer to where the full notice is found lt one line to give the library s name and a brief idea of what it does gt Copyright C lt year gt lt name of author gt This library is free software you can redistribute it and or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation either version 2 1 of the License or at your option any later version This library is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANT
86. P socket pair 10 1 NodeManager API Interface All commands and parameters in the JSON code are strings with the exception of response codes and the static field 10 1 1 Request Keys The request to NodeManager includes the following keys action create delete read update this parameter is only used with the config command command config monitor or version key a configuration key to which the action is being applied node the IP address of a node to which the command applies target openbts sipauthserve smqueue rangesimd ping or rangesysctl value the value to be applied to the configuration key defined in the key parameter 58 10 1 NODEMANAGER API INTERFACE E g This code requests the version of OpenBTS target openbts command version 10 1 2 Response Codes The response codes are based on HTTP 200 action ok with response data 204 action ok with no response data 404 unknown key or action 406 request is invalid 409 conflicting value 500 storing new value failed 501 unknown action 10 1 3 Response Keys The NodeManager response includes the following keys code Response code as specified above data Response data optional depending on the type of request dirty This field is non zero when a parameter is static and could not be applied live meaning the component needs to be restarted to apply the new value E g The version command presented above wi
87. Permitted which must include the NCC of the network E 1 2 How Mobility Works in SIP From the point of view of a SIP switch a mobile SIP user is a user whose IP address changes In Asterisk and the subscriber registry Asterisk supports this with the host dynamic qualifier in the SIP user profile The 120 APPENDIX E MULTI BTS NETWORKS subscriber registry keeps track of the IP address from which a user last registered These IP addresses can be observed from the Asterisk console with the sip show peers command Once a user is registered to a given IP address all inbound calls for that user are routed to that address E 1 3 Combined GSM SIP Mobility in OpenBTS OpenBTS translates every GSM location updating operation into a SIP registration transaction as explained in Section 6 5 1 The MS performs a location update every time it moves into a new location area If we give every BTS a different LAC the MS will perform a location update every time it camps to a new cell resulting in a SIP registration that updates the MS s associated IP address in the Subscriber Registry Because SMQueue also uses the Subscriber Registry for address resolution and message routing SMS routing will be updated as well Note that this mobility approach does not require the Asterisk the subscriber registry or SMQueue servers to have any prior knowledge of the BTS units New BTS units can be added and removed without any modifications to the core netw
88. S may also be no MMContext to indicate the layer2 channel is open but has not yet sent any layer3 messages or no MMUser to indicate that layer3 is connected but the IMSI is not yet known Note to view GPRS channel information use the gprs stat command C 6 config Commands This command displays and modifies parameters in the configuration table Section 4 2 It is possibly the most useful and powerful command in the interface When issued without arguments the config command lists all user level configuration parameters To list the configuration parameters containing a given pattern type 106 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE config lt pattern gt The config command followed by a valid configuration parameter key shows the key s complete description current value default value and valid values config lt key gt Example OpenBTS gt config GSM Identity MCC GSM Identity MCC 001 default description Mobile country code must be three digits Defined in ITU T E 212 Value type string default value 001 visibility level customer site these values are different for each BTS and should not be static 0 valid val regex 0 9 3 scope value must be the same across all nodes The config command treats two arguments as a key value pair and sets the key to a new value config lt key gt lt value gt Example OpenBTS g
89. S networks e GSM Identity MCC Mobile country code must be three digits Defined in ITU T E 212 Value of 001 for test networks e GSM Identity MNC Mobile network code two or three digits Assigned by your national regulator 01 for test networks e GSM Identity ShortName Network short name displayed on some phones Optional but must be defined if you also want the network to send time of day e GSM Radio CO The CO ARFCN Also the base ARFCN for a multi ARFCN configuration B 1 2 Customer Tuneable Parameters These parameters can be changed to optimize your site e Control Emergency Destination Host SIP destination host to be used for the To header of emergency calls This host may be different from the address in SIP Proxy Emergency e Control Emergency Destination User SIP destination user or extension to be used for the To header of emegency calls IMS specifies sos but correct value must be matched to your switch configuration and PSAP interface e Control Emergency QueueTime Maximum time to wait for a channel to open up for an emegency call in a congested system in milliseconds e Control Emergency RFC5031 Use the RFC 5031 URN sip sos SIP Proxy Emergency as the request URN for outbound emergency calls over SIP regardless of the value of Emergency Destination User The To header will still be Emergency Destination UserOEmergency Destination Host e Control Emer
90. This timer is sent to the MS with a granularity of seconds in the range 1 255 The purpose is to postpone the MS RACH procedure until an SDCCH available so there is no point making it any smaller than the expected availability of the SDCCH which will take several seconds Log File Path to use for textfile based logging By default this feature is disabled To enable specify an absolute path to the file you wish to use eg tmp my debug log To disable again execute unconfig Log File Peering ResendCount Number of tries to send message over the peer interface before giving up Peering ResendTimeout Milliseconds before resending a message on the peer interface SGSN Debug Add layer 3 messages to the GGSN Logfile if any SGSN Timer ImplicitDetach 3GPP 24 008 11 2 2 GPRS attached MS is implicitly detached in seconds Should be at least 240 seconds greater than SGSN Timer RAUpdate SGSN Timer MS Idle How long an MS is idle before the SGSN forgets TLLI specific information SGSN Timer RAUpdate Also known as T3312 3GPP 24 008 4 7 2 2 How often MS reports into the SGSN when it is idle in seconds Setting to 0 or 12000 deactivates entirely i e sets the timer to effective infinity Note to prevent GPRS Routing Area Updates you must set both this and GSM Timer T3212 to 0 SGSN Timer Ready Also known as T3314 3GPP 24 008 4 7 2 1 Inactivity period required before MS may perform another routing area
91. ULT O number of times this message has been sent Inside OpenBTS the SMSCB sending loop scans this table at the SMSCB message rate sending the message with the smallest SEND_TIME on each iteration and then updating the SEND_TIME to the current Unix time To schedule messages for delivery an external application provided by the operator creates new entries in the SMSCB database table with a SEND_TIME value of zero To stop delivery of a message permanently delete its record from the table To suspend delivery of a message set its SEND_TIME to the future time at which delivery is to resume A 4 General Packet Radio Service GPRS GPRS General Packet Radio Service is a 2 5G packet data service that supports speeds of up to 30 KByte sec on GSM radio channels GPRS is designed to share physical layer resources with GSM but above the physical layer GPRS is essentially a completely different protocol stack that sits alongside the GSM circuit switched service It is useful therefore to think of a 2 5G BTS unit as having two distinct and largely independent subsystems one for GSM circuit switched services and one for GPRS packet switched services The implementation of GPRS in OpenBTS is subject to the following limitations e No support for handover of IP Internet Protocol sessions If a GPRS handset moves to a new cell its GPRS IP address will change This might disrupt in progress IP transfers Note however that most interactive web bro
92. UR operation is the GSM analog to a SIP REGISTER and OpenBTS maps the LUR to a SIP REGISTER as shown in Figure 6 1 Figure 6 2 shows a more advanced example including challenge response authentication Asterisk uses the simple form with OpenBTS because of differences between GSM and SIP authentication SIPAuthServe uses the challenge response form because it is specifically designed to work with GSM authentication MS OpenBTS Registry LOC UPDATE REQ gt REGISTER _ A LOC UPDATE ACCEPT smmm Figure 6 1 GSM location update mapped to a SIP REGISTER non authenticating case 6 5 2 Call Control Figures 6 3 and 6 4 show the mobile originated and mobile terminated call setup cases using very early assign ment for simplicity In both cases once the channel is established the transaction ladder is essentially that of a SIP ISDN gateway 6 6 Backhaul Capacity Considerations In remote areas with poor network connectivity backhaul bandwidth is often limited or expensive This section describes the effect of Asterisk configuration on backhaul datarate 46 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK MS OpenBTS Registry CHAN REQ sa Q MMED ASSIGN LOC UPDATE REQ mi A 401 Unauthorized lt AUTH REQ LOC UPDATE ACCEPT Figure 6 2 GSM location update mapped to a SIP REGISTER with authentication SIP Switch OpenBTS Handset E Status 100 Trying gt a
93. all QueryRRLP Early Query every MS for its location via RRLP during the setup of a call Control Call QueryRRLP Late Query every MS for its location via RRLP during the teardown of a call Control Emergency RRLP Query every MS for its location via RRLP during an Emergency Call Control LUR QueryRRLP Query every MS for its location via RRLP during LUR Control LUR TestMode Used for testing the LUR procedure Control NumSQLTries Number of times to retry SQL queries before declaring a database access failure Control Reporting TransactionMaxCompletedRecords Maximum completed records to be stored for gathering by an external stats tool Control SACCHTimeout BumpDown Decrease the RSSI by this amount to induce more power in the MS each time we fail to receive a response from it on SACCH Control SMS QueryRRLP Query every MS for its location via RRLP during an SMS Control WatchdogMinutes Number of minutes before the radio watchdog expires and OpenBTS is restarted set to 0 to disable GGSN IP MaxPacketSize Maximum size of an IP packet Should normally be 1520 GGSN IP ReuseTimeout How long IP addresses are reserved after a session ends GGSN Logfile Name If specified internet traffic is logged to this file E g ggsn log GGSN TunName Tunnel device name for GGSN GPRS Channels Congestion Threshold The GPRS channel is considered congested if the desired bandwidth exceeds available b
94. am or its derivative works These actions are prohibited by law if you do not accept this License Therefore by modifying or distributing the Program or any work based on the Program you indicate your acceptance of this License to do so and all its terms and conditions for copying distributing or modifying the Program or works based on it 6 Each time you redistribute the Program or any work based on the Program the recipient automatically receives a license from the original licensor to copy distribute or modify the Program subject to these terms and conditions You may not impose any further restrictions on the recipients exercise of the rights granted herein You are not responsible for enforcing compliance by third parties to this License G 3 GNU GENERAL PUBLIC LICENSE V 2 149 7 Tf as a consequence of a court judgment or allegation of patent infringement or for any other reason not limited to patent issues conditions are imposed on you whether by court order agreement or otherwise that contradict the conditions of this License they do not excuse you from the conditions of this License If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations then as a consequence you may not distribute the Program at all For example if a patent license would not permit royalty free redistribution of the Program by all those who receive copies directly or indire
95. ance counters The format is stats patt clear By default prints all counters When a pattern is provided prints only the counters matching the pattern When issued with the clear option clears all counters C 28 sysinfo Command Prints current system information messages C 29 tmsis Command This command manipulates the TMSI table Section 4 3 The syntax is tmsis a 1 11 r clear dump 1 lt filename gt delete tmsi lt tmsi gt delete imsi lt imsi gt query lt query gt set name value The default action is to print the most recent 100 of TMSI table records The following options apply e a list all records rather than the last 100 e 1 11 longer listing e r raw TMSI table listing Other possible actions are e clear clear the TMSI table e delete imsi lt imsi gt or delete tmsi lt tmsi gt delete an entry for the specified IMSI or TMSI e dump 1 lt filename gt dump the TMSI table to a specified filename e set name value set TMSI database field name to value If value is a string use apostrophes eg set IMSI 12345678901234 114 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE C 30 trans Command Prints completed transaction table in the tabular format The data in the table includes e Active whether the transaction is active or not always no e Tranld Transaction ID e L3TI e Ser
96. andwidth by this amount specified in percent GPRS Channels Congestion Timer How long in seconds GPRS congestion exceeds the Conges tion Threshold before we attempt to allocate another channel for GPRS GPRS Codecs Downlink An empty value specifies GPRS may use all available codecs Otherwise list of allowed GPRS downlink codecs 1 4 for CS 1 CS 4 Currently only 1 and 4 are supported e g 1 4 94 APPENDIX B CONFIGURATION PARAMETERS GPRS Codecs Uplink An empty value specifies GPRS may use all available codecs Otherwise list of allowed GPRS uplink codecs 1 4 for CS 1 CS 4 Currently only 1 and 4 are supported e g 1 4 GPRS Counters Assign Maximum number of assign messages sent GPRS Counters N3101 Counts unused USF responses to detect nonresponsive MS Should be 8 See GSM04 60 Sec 13 GPRS Counters N3103 Counts ACK NACK attempts to detect nonresponsive MS See GSM04 60 sec 13 GPRS Counters N3105 Counts unused RRBP responses to detect nonresponsive MS See GSM04 60 Sec 13 GPRS Counters Reassign Maximum number of reassign messages sent GPRS Counters TbfRelease Maximum number of TBF release messages sent GPRS Debug Toggle GPRS debugging GPRS Downlink KeepAlive How often to send keep alive messages for persistent TBFs in milliseconds must be long enough to avoid simultaneous in flight duplicates and short enough that MS gets one every 5 seconds GSM 5 08
97. anged OpenBTS gt unconfig Control LUR OpenRegistration Control LUR OpenRegistration disabled C 34 uptime Command Shows BTS uptime and BTS frame number C 35 version Command Display version and revision information on the installed version of OpenBTS C 36 Executing OS shell commands from the CLI Commands prepended with an exclamation mark are passed to OS shell for execution grep Register var log OpenBTS log grep IMSI tail n 10 Appendix D Logging in OpenBTS In embedded Range systems OpenBTS logs to rsyslogd or syslogd as facility local7 as well as a log file located at var log OpenBTS log EMERGENCY serious fault associated with service failu ALERT likely service disruption caused by miscor CRITICAL anomalous event that is likely to degrade f ERROR an internal error of the software that ma OpenBTS defines the syslogd logging levels to mean the following WARNING ancanomalous event thatmay indieste a NOTICE anomalous event that probably does not INFO a normal event DEBUG detailed information about internal data The overall logging level for OpenBTS is set in the configuration variable Log Level Logging levels can be set for individual source files by defining a custom configuration variable of the form Log Level filename with a value equal to the desired logging level These log levels are dynamic and can be set and changed in real time with the rawconfig command Se
98. anui using username openbts and its corre sponding password as credentials Press on ESC in any panel to access the NodeManager modal Type your command in JSON format in the Input area and click on post to have it executed The result will appear in the Output area Pressing ESC again hides the modal The source files are available in our GitHub repository at https github com RangeNetworks NodeManager 10 3 PORT UTILIZATION 61 10 3 Port Utilization Every major component of the OpenBTS application suite has its NodeManager thread The thread is a ZeroMQ request response socket which waits for messages on a specific port Each component uses a different port so they are individually addressable application port number OpenBTS 45060 SMQueue 45063 SIPAuthServe 45064 RangeSIMd 45067 NodeManager 45068 Chapter 11 PowerScanner The PowerScanner application scans all ARFCNs on the band specified in the OpenBTS configuration param eter GSM Radio Band and outputs its findings in the sqlite3 data table located at var run OpenBTS PowerScannerResults db In order to execute the command you need to disable the transmitter on your system This can be achieved by stopping the OpenBTS application openbts ubuntu sudo stop openbts Next go to the OpenBTS directory and run the PowerScanner command as a super user openbtsCubuntu cd OpenBTS openbts ubuntu OpenBTS sudo PowerScanner
99. ase station corresponds to T3192 in the MS which is set by GPRS CellOptions T3192Code The T3193 value should be slightly longer than that specified by the T3192Code If 0 the BTS will fill in a default value based on T3192Code GPRS Timers T3195 Nonresponsive downlink TBF resource release timer in milliseconds See GSM04 60 Sec 13 GPRS Uplink KeepAlive How often to send keep alive messages for persistent TBFs in milliseconds must be long enough to avoid simultaneous in flight duplicates and short enough that MS gets one every 5 seconds GPRS Uplink Persist After completion uplink TBFs are held open for this time in milliseconds If non zero must be greater than GPRS Uplink KeepAlive This is broadcast in the beacon and cannot be changed once BTS is started GPRS advanceblocks Number of advance blocks to use in the CCCH reservation GSM CCCH CCCH CONF CCCH configuration type DO NOT CHANGE THIS Value is fixed by the implementation See GSM 10 5 2 11 for encoding Value of 1 means we are using a C V beacon Any other value selects a C IV beacon GSM CellSelection MS TXPWR MAX CCH Cell selection parameters See GSM 04 08 10 5 2 4 GSM CellSelection RXLEV ACCESS MIN Cell selection parameters See GSM 04 08 10 5 2 4 GSM Control GPRSMaxIgnore Ignore GPRS messages on GSM control channels Value is number of consecutive messages to ignore GSM Neighbors Averaging If non zero neighbor measurement
100. ases the cellular operator may also own and operate the VoIP carrier In this example we create a SIP user corresponding to the VoIP carrier and a dialplan context called from trunk where inbound calls from that VoIP carrier are evaluated and routed to an MS First the SIP user representing the VoIP carrier my US voip carrier context from trunk type friend host my US voip carrier com username myVolPCarrierAccountUsername secret myVolPCarrierAccountPassword canreinvite no nat no insecure port invite qualify 5000 dtmfmode auto disallow all allow ulaw Most of these parameters are provided by the carrier The one to note is the context parameter which we are defining as from trunk The meaning of this is that inbound calls from the VoIP carrier will be evaluated for routing in the from trunk context of the dialplan Here is the dialplan entry from extensions conf from trunk route incoming calls from the PSTN 6 5 HYBRID GSM SIP TRANSACTIONS 45 exten gt s 1 Answer exten gt 17075556025 1 Dial SIP IMSI001731234567890 The meaning of this is that inbound calls to 17075556025 are routed to SIP user IMSI001731234567890 6 5 Hybrid GSM SIP Transactions 6 5 1 Registration Location Updating When an MS enters a new location area in a GSM network it performs a location update request LUR The network can also instruct the MS to perform the LUR periodically on a timer The L
101. ation parameter gives a list of IP addresses from which the BTS will request information These requests are repeated at a configurable period usually every 10 seconds using the RPP REQ NEIGHBOR_PARAMS and RPP RSP NEIGHBOR_PARAMS messages Measurement Reports The serving BTS unit is responsible for making the decision to initiate a handover The decision is made based on measurement reports from the handset of other BTS units in the area During a call there is a constant exchange of control information between the BTS unit and the handset Most of this information concerns the receiver signal strength indications RSSI of neighboring BTS units so that the network can decide which BTS unit is best suited to serve the handset The handset makes these measurements during the idle periods between active timeslots Since the call is carried on a single slot the handset is idle at least 87 5 of the time during the call e In the downlink direction the BTS unit sends to the handset a list of neighboring BTS units to measure e In the uplink direction the handset sends signal level information for those neighbors that it can measure This exchange occurs on the SACCH roughly every 0 6 second during a call Every time this exchange occurs the BTS unit makes a decision as to whether or not to initiate a handover The decision algorithm is 1 If the RSSI of the serving BTS is greater than GSM Handover LocalRSSIMin given in dBm do
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103. be produced in a few seconds Since the development of this cloning technique most SIM manufacturers have taken at least one of these steps to prevent cloning e Use a better algorithm than COMP128v1 for A3 A8 one that is not compromised and not likely to be The industry standard is currently COMP128v3 6 3 EMERGENCY CALLS 43 e Design SIMs to shut down or self destruct if too many A3 A8 calculations are requested too quickly With this precaution even COMP128v1 SIMs are reasonably secure against cloning Avoiding Cloned SIMs Once a SIMs is cloned it is impossible to distinguish the clones from the original or from each other The IMSI in a cloned SIM becomes useless as a subscriber identity so the proper approach for dealing with cloned SIMs is to detect them through conventional fraud detection techniques unprovision them and maintain a blacklist of their IMSIs In a multi BTS network there is no practical way for a single BTS unit to detect cloned SIMs therefore clone detection is not part of OpenBTS itself but must be performed by the core network The main sign of a cloned SIM is that the subscriber appears to be moving frequently between geographically disjoint cells or attempts to make multiple simultaneous calls especially from different cells 6 3 Emergency Calls This section applies to the commercial release only In GSM the emergency call is a special transaction distinct from ordinary mobile originated call setup T
104. bles and Structures 4 1 Manipulating OpenBTS Databases 42 The Configuration Table lt 2 sies eson d mir wee epee Oe ES oe eee eet 10 11 12 13 14 15 16 19 19 20 20 24 25 25 26 CONTENTS Aa TMS Table 22d a A A a A ra 4 4 Transaction Tabl so e poe dose atog a ia Be aw a Hew Boe doe 45 Channel Table oe o e e 2 eee we G4 ea Baw a Rw eS OpenBTS and the Transceiver 5 1 Downlink Power and Congestion Management 5 2 Uplink Power and Timing Control 2 SIPAuthServe Subscriber Registry and Asterisk 6 1 Subscriber Registry e ss sec 2 oson a e Ea aa 6 2 Provisioning New Subscribers ooa 0 e e 6 3 Emergency Call a soso 6244 8 ue Roe a a a a 6 4 Connecting toa VoIP Carrier coso sa a doron ee net 6 5 Hybrid GSM SIP Transactions i 424 0 49849 444 Oo bot 6 6 Backhaul Capacity Considerations 0 SMQueue 7 1 Design and Operation of SMQueue 2 02208 7 2 Configuring SMQuete s lt s p sg a salpe phi eme ru oa ae aa a 7 3 Short Code Applications s escars o ee Other GSM Services 8 1 Short Message Service Cell Broadcast SMSCB 8 2 Radio Resource Location Protocol RRLP General Packet Radio Service GPRS 9 1 Configuring GPRS in OpeNBTS 0 e 9 2 Configuration of Handsets for OpenBTS GPRS 9 3 Using CLI to Monitor and Control GPRS 10 Nod
105. cation shuts down it starts automatically provided it is configured as an upstart service but loses connection to the CLI Restart the CLI to connect to OpenBTS again 3 3 2 Using the CLI The CLI interface is simple write a command string at the CLI prompt and press Enter then read back the result string s For a list of available commands type help at the CLI prompt and press Enter Use help followed by a command name to get a description of a specific command OpenBTS gt help rxgain rxgain newRxgain get set the RX gain in dB OpenBTS gt A detailed list of CLI commands is provided in Appendix C Using the CLI to Configure the OpenBTS The command to inspect and modify the OpenBTS configuration parameters is config The parameters are case sensitive They are stored in the configuration table see section 4 2 The complete list of configuration parameters and their meanings is provided in Appendix B 22 CHAPTER 3 GETTING TO KNOW YOUR OPENBTS SYSTEM The config command followed by a configuration parameter name provides full details on that parameter including the current value the default value the range of acceptable values and whether the parameter is static or dynamic For example OpenBTS gt config GSM Identity ShortName GSM Identity ShortName Range default description type default value visibility level static valid val regex scope OpenBTS g
106. cation vnd 3gpp sms MIME payload in a SIP MESSAGE method and waits for a response 200 OK or 202 Queued for success or 4xx or timeout for failure After sending CP DATA to an MS OpenBTS waits for CP ACK or CP ERROR proceeding after CP ACK or aborting the transaction after CP ERROR SMS in L4 The Um L4 part of SMS uses four messages e RP DATA to transfer a TPDU across Um and into L5 e RP ACK to acknowledge the transfer of a TPDU across Um and into L5 e RP ERROR to report the failure to transfer an TPDU to L5 e RP SMMA for the MS to report that it has more memory available to receive SMS messages not yet supported by OpenBTS An TPDU is a transfer layer protocol data unit which is just an encapsulation of a message from L5 OpenBTS translates between SIP and SMS L4 as follows e RP DATA MESSAGE method with the RPDU as an application vnd 3gpp sms MIME payload e RP ACK 200 OK or 202 Queued response e RP ERROR any other response or timeout e RP SMMA not yet supported by OpenBTS SMS in L5 The Um L5 part of SMS uses these message e SMS SUBMIT to transfer a text message from the MS to the network e SMS DELIVER to transfer a text message from the network to the MS OpenBTS transfers L5 PDUs TPDUs as opaque payloads SMQueue manipulates L5 headers as needed to convert SMS SUMBIT TPDUs into SMS DELIVER TPDUs during the delivery process A 2 TEXT MESSAGING SMS 75 RFC 3428 SMS Transaction Ladders
107. ch case this License incorporates the limitation as if written in the body of this License 9 The Free Software Foundation may publish revised and or new versions of the General Public License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If the Program specifies a version number of this License which applies to it and any 150 APPENDIX G FOSS LICENSES later version you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation If the Program does not specify a version number of this License you may choose any version ever published by the Free Software Foundation 10 If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different write to the author to ask for permission For software which is copyrighted by the Free Software Foundation write to the Free Software Foundation we sometimes make exceptions for this Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally NO WARRANTY 11 BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE THERE IS NO WARRANTY FOR THE PROGRAM TO THE EXTENT PERMITTED BY APPLICABLE LAW EXCEPT WHE
108. concerns Each version is given a distinguishing version number If the Library as you received it specifies that a certain numbered version of the GNU Lesser General Public License or any later version applies to it you have the option of following the terms and conditions either of that published version or of any later version published by the Free Software Foundation If the Library as you received it does not specify a version number of the GNU Lesser General Public License you may choose any version of the GNU Lesser General Public License ever published by the Free Software Foundation If the Library as you received it specifies that a proxy can decide whether future versions of the GNU Lesser General Public License shall apply that proxy s public statement of acceptance of any version is permanent authorization for you to choose that version for the Library G 7 BSD Licenses G 7 1 BSD License on the A5 1 Implementation Copyright C 1998 1999 Marc Briceno lan Goldberg and David Wagner The source code below is optimized for instructional value and clarity Performance will be terrible but that s not the point The algorithm is written in the C programming language to avoid ambiguities inherent to the English language Complain to the 9th Circuit of Appeals if you have a problem with that This software may be export controlled by US law G 7 BSD LICENSES 179 This software is free for commercial and non commercial use as
109. configuration param eter to point to a database file that contains the messages for delivery e g var run OpenBTS SMSCB db To disable again execute unconfig Control SMSCB Table As of the current version OpenBTS does not include an application to create entries or otherwise modify the message table Please refer to Appendix section A 3 2 for the data table schema and additional developer information 8 2 Radio Resource Location Protocol RRLP RRLP is the protocol used between the network and MS to manage location services LCS As of OpenBTS version 4 0 the implementation of RRLP is in the development stage and is only mentioned in this manual for future reference 53 Chapter 9 General Packet Radio Service GPRS 9 1 Configuring GPRS in OpenBTS o eee ee ee 54 9 1 1 Assigning a Range of IP Addresses to GPRS 0 0 o 2 54 9 1 2 Configuration Parameters for BSS Functions o o 55 9 1 3 Configuration Parameters for SGSN Functions o o 56 9 1 4 Configuration Parameters for GGSN Functions o e 56 9 2 Configuration of Handsets for OpenBTS GPRS o 57 9 21 APN Settings 250 o o a da ad a de r S 57 9 2 2 Data Roaming soccer 57 9 3 Using CLI to Monitor and Control GPRS o o 57 GPRS General Packet Radio Service is a 2 5G packet data service that supports speeds of up to 30 KByte sec on GSM radio channels
110. ction C 20 For example rawconfig Log Level CallControl cpp INFO sets the logging level to INFO for all functions in the file CallControl cpp Some useful logging settings are e rawconfig Log Level GSML2LAPDm cpp INFO for an L2 trace e rawconfig Log Level RadioResource cpp INFO for an L3 RR trace e rawconfig Log Level MobilityManagement cpp INFO for an L3 MM trace e rawconfig Log Level CallControl cpp INFO for an L3 CC trace e rawconfig Log Level SIPInterface cpp INFO for a trace of all SIP messages e rawconfig Log Level SIPEngine cpp INFO for a trace of SIP state machine activity e rawconfig Log Level SMSControl cpp INFO for a trace of L3 SMS activity Log events at the CRIT ALERT and EMERGENCY levels are treated as special cases inside OpenBTS 116 117 e High level log events are echoed to the OpenBTS stdout regardless of the Log LogFile and Log Level settings or the configuration of syslogd e High level log events are stored in an internal table accessible from the CLI Section C 1 The maximum size of this table is set with the Log Alarms Max configuration value Certain components of OpenBTS can be configured to log their activity to their own log files In order to enable a certain type of log set the corresponding configuration parameter to a desired file path using the devconfig command e GGSN Logfile Name setting this developer level parameter enables loggi
111. ctly through you then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program If any portion of this section is held invalid or unenforceable under any particular circumstance the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims this section has the sole purpose of protecting the integrity of the free software distribution system which is implemented by public license practices Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system it is up to the author donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License 8 If the distribution and or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries so that distribution is permitted only in or among countries not thus excluded In su
112. d into a collective whole A work that constitutes a Collection will not be considered an Adaptation as defined below for the purposes of this License Creative Commons Compatible License means a license that is listed at http creativecommons org compatiblelicenses that has been approved by Creative Commons as being essentially equivalent to this License including at a minimum because that license i contains terms that have the same purpose meaning and effect as the Li cense Elements of this License and ii explicitly permits the relicensing of adaptations of works made available under that license under this License or a Creative Commons jurisdiction license with the same License Elements as this License Distribute means to make available to the public the original and copies of the Work or Adaptation as appropriate through sale or other transfer of ownership License Elements means the following high level license attributes as selected by Licensor and indicated in the title of this License Attribution ShareAlike Licensor means the individual individuals entity or entities that offer s the Work under the terms of this License Original Author means in the case of a literary or artistic work the individual individuals entity or entities who created the Work or if no individual or entity can be identified the publisher and in addition i in the case of a performance the actors s
113. dditional sources of delay first the extra back off delay can result in the channel going idle which typically happens only for transfers near the threshold second bandwidth may be wasted by unnecessary packet retransmission which for large transfers can grow exponentially This means that for a typical GPRS connection with a download bandwidth 30 KB sec the maximum size web page that can be viewed is about 75KB before additional extraneous delay is added by the TCP algorithm That s why there are websites custom tailored for cell phones It is also why measuring GPRS performance by downloading a 100KB file is inaccurate GPRS Channel Allocation The operator must decide how many channels timeslots to dedicate for GPRS services and how many to dedicate for CS Circuit Switched i e voice services On startup the GRPS subsystem will take over the specified number of Combination physical channels timeslots and dedicate them to GPRS service converting them to Combination Xlll These physical channels are taken as contiguous groups on the same ARFCN when possible The number of channels is specified by configuration parameters GPRS Channels Min CO and GPRS Channels Min CN Currently the number of GPRS channels is fixed at startup and cannot be changed without restarting OpenBTS The reason the operator can specify the number of GPRS channels for ARFCN CO separately is to balance the system resources between GSM and GPRS services
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115. described in GSM 05 08 Section 10 2 1 The formula iS P min To Tc a C 48 Pm where e P is the transmitted power in dBm e T is 39 dBm in the low bands and 36 dBm in the high bands e Ic is a configurable parameter with units of dB encoded into the parameter GPRS MS Power Gamma in 2 dB steps For example a configured value of 16 would give Tc of 32 dB e a is a unitless configurable parameter encoded into the configuration parameter GPRS MS Power Alpha in steps of 0 1 For example a configured value of 5 would give a of 0 5 A 4 GENERAL PACKET RADIO SERVICE GPRS 83 e C is the RSSI of the network downlink signal as measured by the handset e Pm is the maximum transmission power of the handset usually 33 dBm For a low band 850 or 900 MHz BTS unit with an output of 33 dBm per ARFCN values of a 1 0 and Tc 58 dB will cause the handset to hit maximum output power when the downlink RSSI hits 100 dBm Values of a 1 0 and Tce 60 dB will have the same effect in the high band For every dB of power that the BTS output is increased y should be decreased by a corresponding dB The corresponding configuration parameters are e GPRS MS Power Alpha The a parameter x10 to give a step size of 0 1 so a 1 0 is encoded as a value of 10 e GPRS MS Power Gamma The Ic parameter 2 to give a step size of 2 dB so T o 58 dB is encoded as a value of 29 and Tc 60 dB is encoded as a value of 30
116. e these values are different for each BTS and should not be static 0 valid val regex 0 9a zA Z scope value must be the same across all nodes OpenBTS gt To set a configuration parameter to an empty value use the unconfig command For example OpenBTS gt unconfig Control LUR OpenRegistration Control LUR OpenRegistration disabled OpenBTS gt 3 3 3 Using the CLI to Access a Remote Node By default the OpenBTS CLI operates over a TCP socket on port 49300 of the 127 0 0 1 interface These defaults can be changed with the CLI Port and CLI Interface parameters using the devconfig command to allow network access OpenBTS gt devconfig CLI Interface 192 168 0 42 CLI Interface changed from 127 0 0 1 to 192 168 0 42 OpenBTS gt The CLI can connect to OpenBTS running on a different IP and or port Provide the p option to specify an alternative port and the t option to specify the IP address of a target system For example gt OpenBTS OpenBTSCLI t 192 168 0 42 p 49333 3 3 4 Using the CLI in Development The CLI interface is simple it reads a command string at the CLI socket and returns the result string s Any number of outside applications can access the CLI at the same time It can also execute commands in non interactive mode making it possible to use the CLI capabilities in third party tools e g shell scripts Two options offer slightly different modes of operation the
117. e handset models exhibit bugs when VEA is used and these bugs may affect performance GGSN DNS The list of DNS servers to be used by downstream clients By default DNS servers of the host system are used To override specify a space separated list of DNS servers in IP dotted notation eg 1 2 3 4 5 6 7 8 To use the host system DNS servers again execute unconfig GGSN DNS GGSN Firewall Enable 0 no firewall 1 block MS attempted access to OpenBTS or other MS 2 block all private IP addresses GGSN IP TossDuplicatePackets Toss duplicate TCP IP packets to prevent unnecessary traffic on the radio GGSN MS IP Base Base IP address assigned to MS GGSN MS IP MaxCount Number of IP addresses to use for MS GGSN MS IP Route A route address to be used for downstream clients By default OpenBTS man ufactures this value from the GGSN MS IP Base assuming a 24 bit mask To override specify a route address in the form xxx xxx xxx xxx yy The address must encompass all MS IP addresses To use the auto generated value again execute unconfig GGSN MS IP Route OPENBTS PARAMETERS 89 GGSN Shel1Script A shell script to be invoked when MS devices attach or create IP connections By default this feature is disabled To enable specify an absolute path to the script you wish to execute e g usr bin ms attach sh To disable again execute unconfig GGSN ShellScript GPRS Cell0Options T3168Code Timer 3168 in th
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119. e A Reeve Br e Doe e Cll handover Command sspe as 5a 644 a Se See aoe ew De eee es C12 help Commands ac ow de aoe ee ke ee Gwe Ble a ade ae a ae CIS Load Commands a gc anu lO a a a a C 14 memstat Command C15 neighbors Command 4 4 s e ndie a te ck Ha ee a Bad Se a e C16 noise Command e isos cng Glo eR Sa we ae ee ae ar ii C17 notices Command s lt lt sec 6 ae bee oe ea oe ee a ee CONTENTS 62 63 64 a FR Ge 64 ae 72 ea EB aed 76 re T7 85 CONTENTS F Calg page Command se seis a APG eTa ai a ee ee A a aa C19 power Command ea Ghica eh ew A b A ae a Be Oe oe Ee s C 20 ravcontig Command ss ace a s Ma A iogh ws Se ae we a a d C 21 regperiod Command 2 00 0 a a a i a Ea E ies C 22 rmconfie Command ses s ieta h aopa a eR a ee dd eee a a C23 regain Command ad A a a A E A ab aa i C 24 sendsimple and sendsms Commands 000 eee ee ee C25 seen Command se c 4 ae nt at deg on Ede AG Bob BO ee o oe a id C26 shutdown Command s sus p seed oe eb eGe Ve eee a te bo ie ee OE ee a e C27 stats Command ve 44 ea d Pe aah Oe a ede Se Bae ea Ea a a i C23 sysinto Command lianas eae Se ae ee ei hee eo oe Ee e g C20 tusis Commands 24 4 ae a 2h a BE fe mee ee Pe aa a ar C30 trans COMMANA 4 4 2 bd be ie RA OG Gash AS Beek eh hoe Be ee de C 31 trefactory Command es se coet 21 eo p46 a be bea ed eed had
120. e MS controls the wait time after sending a Packet Resource Request to initiate a TBF before giving up or reattempting a Packet Access Procedure which may imply sending a new RACH This code is broadcast to the MS in the COTO beacon in the GPRS Cell Options IE See GSM 04 60 12 24 Range 0 7 representing values from 0 5sec to 4sec in 0 5sec steps GPRS Cell0ptions T3192Code Timer 3192 in the MS specifies the time MS continues to listen on PDCH after all downlink TBFs are finished and is used to reduce unnecessary RACH traffic This code is broadcast to the MS in the COTO beacon in the GPRS Cell Options IE The value must be one of the codes described in GSM 04 60 12 24 Value 0 implies 500msec 2 implies 1500msec 3 imples Omsec GPRS ChannelCodingControl RSSI If the initial unlink signal strength is less than this amount in dB GPRS uses a lower bandwidth but more robust encoding CS 1 This value should normally be GSM Radio RSSITarget 10 dB GPRS Channels Min CO Minimum number of channels allocated for GPRS service on ARFCN CO GPRS Channels Min CN Minimum number of channels allocated for GPRS service on ARFCNs other than CO GPRS Enable If enabled GPRS service is advertised in the COTO beacon and GPRS service may be started on demand See also GPRS Channels GPRS LocalTLLI Enable Enable recognition of local TLLI GPRS Multislot Max Downlink Maximum number of channels used for a single MS in downlink
121. e Networks 3 Phone Starter Kit part 8810 000 0 and the Range Networks hardware at the same time your system already has the SIM cards provisioned Similarly if you generated the SIMs using the Range Networks SIM Reader Programmer connected to your system they are already provisioned Additional blank SIM cards are available from Range Networks part 8430 999 0 Extension Phone Numbers Used for Testing Each SIM card that will be used in the tests needs to be assigned an extension phone number In order to assign and or update a phone number associated with a SIM access the Subscriber Registry HTTP interface described in section 6 1 2 using your web browser Click the Link number action corresponding to an 130 F 1 TEST SIM PROCEDURES 131 IMSI of the SIM card specify the number and click on Link Once entered it should appear in the Phone number column of the table The loopback number defined in the default Asterisk configuration is 2600 F 1 1 Tests with the Test SIM The supported tests are e Location updating e MOC to a loopback where the handset dials 2600 e MOC to a handset where the originating handset dials the number assigned to the terminating handset e Loopback SMS MO SMS and MT SMS where a handset sends SMS to its extension number and waits for the result e SMS with a parallel call where a handset starts a loopback call to 2600 then sends SMS to another phone while still on a ca
122. e embedded computer This is shown in Figure 2 1 In a slightly larger network with a small number of access points and good IP connectivity between them one access point can be designated as a master and provide servers for the rest of the network Figure 2 2 shows an example of a network of two access points with one access point hosting the server for both This is a simple configuration for small multi BTS networks It is also a preferred configuration for cell sites that co locate multiple access points sharing a common network connection The OpenBTS and Transceiver applications must run inside each GSM SIP access point The Asterisk and the Subscriber Registry application SIPAuthServe communicate through the filesystem and therefore must run on the same computer but that computer can be remote from the access point SMQueue and the other servers can run anywhere and may have multiple instances 2 2 NETWORK ORGANIZATION 17 Full Band Digital Radio Transceiver USB2 smqueue H Transcevier Radiomodem SMS Processor IAX SIP HTTP S UDP SIP SQL SMTP SMTP ee SIP subscriber registry SIP IP Network SQL Database Server HTTP S Interface Protocol Processor SIP RTP SIP RTP SQL IAX SIP IAX Softswitch Figure 2 1 Components of the OpenBTS application suite and their communication channels as installed in each access point Sharp cornered boxes are hardware components Round cornered boxes are software compon
123. e fee royalty or other charge for exercise of rights granted under this License and you may not initiate litigation including a cross claim or counterclaim in a lawsuit alleging that any patent claim is infringed by making using selling offering for sale or importing the Program or any portion of it 11 Patents A contributor is a copyright holder who authorizes use under this License of the Program or a work on which the Program is based The work thus licensed is called the contributor s contributor version A contributor s essential patent claims are all patent claims 162 APPENDIX G FOSS LICENSES owned or controlled by the contributor whether already acquired or hereafter acquired that would be infringed by some manner permitted by this License of making using or selling its contributor version but do not include claims that would be infringed only as a consequence of further modification of the contributor version For purposes of this definition control includes the right to grant patent sublicenses in a manner consistent with the requirements of this License Each contributor grants you a non exclusive worldwide royalty free patent license under the contributor s essential patent claims to make use sell offer for sale import and otherwise run modify and propagate the contents of its contributor version In the following three paragraphs a patent license is any express agreement or commitme
124. e if he or she is willing to distribute software through any other system and a licensee cannot impose that choice This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License 12 If the distribution and or use of the Library is restricted in certain countries either by patents or by copyrighted interfaces the original copyright holder who places the Library under this License may add an explicit geographical distribution limitation excluding those countries so that distribution is permitted only in or among countries not thus excluded In such case this License incorporates the limitation as if written in the body of this License 13 The Free Software Foundation may publish revised and or new versions of the Lesser General Public License from time to time Such new versions will be similar in spirit to the present version but may differ in detail to address new problems or concerns Each version is given a distinguishing version number If the Library specifies a version number of this License which applies to it and any later version you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation If the Library does not specify a G 5 GNU LESSER GENERAL PUBLIC LICENSE V 2 1 175 license version number you may choose any version ever published by the Free Software Foundation 14 If you wish
125. e sqlite3 database holding the subscriber registry e savefile The file to save SMS messages to when exiting B 2 3 Developer Factory Parameters These parameters should only be changed by when developing new code e Control NumSQLTries Number of times to retry SQL queries before declaring a database access failure e Debug print_as_we_validate Generate lots of output during validation e Log File Path to use for textfile based logging By default this feature is disabled To enable specify an absolute path to the file you wish to use eg tmp my debug log e SC WhiplashQuit Code Short code to the application which will make the server quit for valgrind leak checking Intended for developer use only e SC WhiplashQuit Password Password which must be sent in the message to the application at SC WhiplashQuit Code e SC WhiplashQuit SaveFile Contents of the queue will be dumped to this file when SC WhiplashQuit Code is activated B 3 SIPAUTHSERVE PARAMETERS 101 e SC ZapQueued Code Short code to the application which will remove a message from the queue by its tag If first char is do not reply just do it If argument is SC ZapQueued Password then delete any queued message with timeout greater than 5000 seconds e SC ZapQueued Password Password which must be sent in the message to the application at SC ZapQueued Code B 3 SIPAuthServe Parameters SIPAuthServe configuration param
126. eManager 10 1 NodeManager API Interface o o 20202002 10 2 Running NodeManager Queries o o e e 10 3 Port Utilization c e a4 os ww ok Gab ee BW bo ee ees 29 30 30 32 32 34 35 36 38 43 44 45 45 50 50 51 51 53 53 53 54 54 57 57 11 PowerScanner Appendices A OpenBTS Implementation of GSM amp 3GPP Specifications and IETF Standards A 1 The OpenBTS GSM Air Interface 0 ee A 2 Text Messaging SMS 2 24 to a aada 68d 0444444544645 68 54 4 8 A 3 Short Message Service Cell Broadcast SMSCB 2 004 A 4 General Packet Radio Service GPRS 0 o e B Configuration Parameters Bul OpenBIS Parameters sore re a A Sh Ee B 2 Smqueue Parameters B 3 SlPAuthServe Parameters 00 ee C The Command Line Interface CLI Reference Cl alarms Command lt 22525448446 660 4 90 45 84 14 bh 4 Lee C2 audit Command s ose io 68 5 eee de ew de we E C3 calls Command s ses re r 2464 4 4 644 bea bt GEE DSSS C4 gellid Command 2 524644 6245454685464 66 84404 4 SSO C5 chans Comimand a 45 45 446 24844 a e HS CO econtics Commands i 34 oad be tS eh Ae es bee HE ES C 7 deveontig Command s ee c r hs aa bse wis aor dla a Ge e i C8 endcall Command 22 200858 5 208 dunga Page ene A ER RR C9 freqeorr Command s iee oeus a Ee a aw ee e a ee CAO spre Command cs siena jos w b
127. eaving with a new block starting on every fourth burst and any given burst containing bits from two different traffic frames This interleaving pattern makes the TCH robust against single burst fades since the loss of a single burst destroys only 1 8 of the frame s channel bits a 12 5 bit erasure The coding of a traffic channel is dependent on the traffic or vocoder type employed with most coders capable of overcoming single burst losses All traffic channels use a 26 multiframe TDMA structure Full rate channels TCH F A GSM full rate channel uses 24 frames out of a 26 multiframe The channel bit rate of a full rate GSM channel is 22 7 kbit s although the actual payload data rate is 9 6 14 kbit s depending on the channel coding OpenBTS supports only the GSM full rate codec GSM 06 10 as a media type on this channel 68 APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS Dedicated Control Channels DCCHs These point to point channels correspond to the ISDN D channel and are referred to as Dm channels Standalone Dedicated Control Channel SDCCH The SDCCH is used for most short transactions includ ing initial call setup step registration and SMS transfer lt has a payload data rate of 0 8 kbit s Up to eight SDCCHs can be time multiplexed onto a single physical channel The SDCCH uses 4 burst block interleaving in a 51 multiframe One SDCCH channel can be used to process 10 15 location updates per minu
128. ections You must unless a request has been made pursuant to Section 4 a keep intact all copyright notices for the Work and provide reasonable to the medium or means You are utilizing i the name of the Original Author or pseudonym if applicable if supplied and or if the Original Author and or Licensor designate another party or parties e g a sponsor institute publishing entity journal for attribution Attribution Parties in Licensor s copyright notice terms of service or by other reasonable means the name of such party or parties ii the title of the Work if supplied iii to the extent reasonably practicable the URI if any that Licensor specifies to be associated with the Work unless such URI does not refer to the copyright notice or licensing information for the Work and iv consistent with Ssection 3 b in the case of an Adaptation a credit identifying the use of the Work in the Adaptation e g French translation of the Work by Original Author or Screenplay based on original Work by Original Author The credit required by this Section 4 c may be implemented in any reasonable manner provided however that in the case of a Adaptation or Collection at a minimum such credit will appear if a credit for 138 APPENDIX G FOSS LICENSES all contributing authors of the Adaptation or Collection appears then as part of these credits and in a manner at least as prominent as the credits for the other contribut
129. ed session a virtual circuit similar to the virtual connection of RTP or TCP IP This model assumes an always on network connection where the maintenance of the circuit with occasional keep alive messages is cheap and reasonable GSM SMS is different Maintaining the channel is expensive There is no keep alive message mechanism The circuit switched connection is created and destroyed with every transfer in a process that can take hundreds of milliseconds Each message transfer is an independent transaction There is no natural notion of a session RFC 3428 RFC 3428 is an IETF standard for the transfer of short messages over the internet Among IETF IP protocols for messaging RFC 3428 is special in that it supports page mode messaging without any notion of a session there is no INVITE to start the transaction or BYE to end it This makes it a natural fit for SMS RFC 3428 is straightforward The sending entity sends a SIP MESSAGE method to the intended receiver The receiver gives one of the standard SIP responses preferably 200 OK or 202 Queued to indicate a successful transfer or a 4xx or 5xx response to indicate failure A 2 2 Text Messaging in GSM GSM 04 11 and 03 40 define conventional SMS in five layers 1 L1 is taken from the Dm channel type used either SDCCH or SACCH This layer terminates in the BSC L2 is normally LAPDm This layer terminates in the BTS L3 the connection layer is defined in GSM 04 11 Section
130. ee es C32 txatten Command exa 4 848 a Gea oA oe he ee oe ab es C33 uncontig Command s a eo 40444 0844 Rw eS HOG ee ee elaka a ge Sx C34 uptime Command w sis sa gie a due RR be doe ee d C35 version Command o ie ses al w Bie a eae Me Re co a ic ea ar ke TE C 36 Executing OS shell commands from the CLI e sore so soie 0 o Logging in OpenBTS Multi BTS Networks E 1 How Mobility Works sa coea ee E 2 Example of Mobility Configuration Simple Case 2 ee E 3 Example of Mobility Configuration More Advanced Case 0200000048 E4 Handover s essc reds ebb eee eee eee ea ed ee bee ea E 5 Remote Logging e s 2544254 246 be ee eee he Bee a a ed Test Procedures F 1 Test SIM Procedures a ee es F 2 Testing with Open Registration i oc ioe e aa e E a oa ee 109 110 110 111 111 111 112 112 112 113 113 113 114 114 114 115 115 115 115 116 118 118 120 122 123 126 6 CONTENTS G FOSS Licenses 134 Gel Creative Commons License c 4 23 o Bie a eb Oa E ee e Gog Ge ee ig 134 G 2 GNU General Public License v l aaaea aaa a 139 G 3 GNU General Public License v 2 2 aaa aa 144 G 4 GNU General Public License v 8 2 a aa a a 152 G 5 GNU Lesser General Public License v 2 1 2 0 0000 aa 166 G 6 GNU Lesser General Public License v 3 2 20 00 e 176 G 7 BSD licenses son a e At ae a ee a ee ee ee ee te A a 178 Chapter 1 General Information 1 1 Scope
131. ee if the Transceiver can be reached TRX TxAtten0Offset Hardware specific gain adjustment for transmitter matched to the power amplifier expessed as an attenuation in dB Set at the factory Do not adjust without proper calibration Test GSM SimulatedFER Downlink Probability 0 100 of dropping any downlink frame to test ro bustness Test GSM SimulatedFER Uplink Probability 0 100 of dropping any uplink frame to test robustness Test GSM UplinkFuzzingRate Probability 0 100 of flipping a bit in any uplink frame to test robust ness Test SIP SimulatedPacketLoss Probability 0 100 of dropping any inbound or outbound SIP packet to test robustness B 2 Smqueue Parameters Smqueue configuration parameters are stored in Smqueue Configuration Table located at etc OpenBTS smqueue db The schema is identical to the OpenBTS Configuration Table discussed in section 4 1 B 2 1 Customer Site Parameters None defined at this time B 2 2 Customer Tuneable Parameters These parameters can be changed to optimize your site Asterisk address The Asterisk SIP PBX IP address and port Bounce Code The short code that bounced messages originate from Bounce Message IMSILookupFailed The bounce message that is sent when the originating IMSI cannot be verified Bounce Message NotRegistered Bounce message indicating that the destination phone is not regis tered CDRFile Log CDRs here To e
132. eex This codec can operate at rates as low as 4 kbit sec and has speech quality and computational complexity similar to G 729 at 8 kbit sec The advantages of Speex are greater configuration flexibility and freedom from licensing fees Support for Speex is growing among VolP carriers e LPC 10 This is a low complexity 2 4 kbit sec codec The speech is understandable but often unnatural sounding Asterisk will automatically transcode as needed between GSM FR and any of these codecs 6 6 2 RTP IAX Overhead and Trunking The media protocol most commonly used with SIP is RTP IETF RFC 3550 When any codec is run over RTP there is an additional overhead of roughly 17 kbit sec per call when used with a 20 ms codec frame Yes for 48 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK most codecs the overhead of RTP is greater than the bandwidth requirement of the codec itself Asterisk also supports a combined signaling and media protocol called IAX Inter Asterisk eXchange IAX has an overhead of roughly 20 kbit sec with a codec frame size of 20 ms but unlike RTP IAX can distribute this overhead over many calls through a technique called IAX trunking Trunking can be applied to allow any set of calls between a pair of switches to share a common IAX channel and amortize their overhead Table 6 1 Backhaul bandwidth for various codec trunking configurations All rates in kbit sec and assuming 20 ms framing
133. elected by the SIM manufacturers and usually given to the carriers under NDA Authentication and Kc generation are closely connected so Kc is generated even if ciphering will not be used Anonymization The TMSI is a 32 bit temporary mobile subscriber identity that can be used to minimized the sending of the IMSI in the clear on Um The TMSI is assigned by the network with the MM TMSI Reallocation Command during the location updating procedure Once the TMSI is established it can be used to anonymize future transactions A 1 4 Service Capacity of Um The capacities of OpenBTS products ARFCN for ARFCN are the same as for any other GSM base stations The only exception to this is that OpenBTS does not yet support half rate channels OpenBTS offers two types of dedicated channels e Full Rate Traffic Channel TCH F Each Combination slot contains a single TCH F that can carry a single speech call A 1 THE OPENBTS GSM AIR INTERFACE 71 e Standalone Dedicated Control Channel SDCCH Each Combination VII slot carries eight SDCCHs The Combination V beacon also carries four SDCCHs Each SDCCH can process about 30 authenticated registration transactions per minute or transfer about 12 text messages per minute assuming good link margins Bear in mind that poor link margins will significantly degrade SDCCH capacity by forcing retransmission of L2 frames and requiring long tear down times for dropped channels A typical configuration for a si
134. en if it matches Control LUR OpenRegistration By default this filter is disabled To enable the filter specify a regu lar expression E g 666 matches any IMSI starting with 666 which currently does not correspond to any known MCC Stay on the light side of the Force To disable the filter again execute unconfig Control LUR OpenRegistration Reject If Control LUR OpenRegistration is disabled this parame ter has no effect Control LUR OpenRegistration ShortCode The return address for the open registration message Control LUR QueryClassmark Query every MS for classmark during LUR Control LUR QueryIMEI Query every MS for IMEI during initial LUR 88 APPENDIX B CONFIGURATION PARAMETERS Control LUR RegistrationMessageFrequency This option helps determine when a registration mes sage is sent by the BTS to a handset If PLMN the message is sent only when the handset first registers in the PLMN as reported by the handset If NORMAL the message is sent whenever the handset enters the cell as reported by the handset If FIRST the message is sent the first time this BTS sees this MS as determined by the WELCOME SENT field of the TMSI_TABLE This option is not completely reliable because the functioning of this option depends on information provided by the handset during their initial attach procedure and some handsets set this information improperly Control LUR SendTMSIs Send new TMSI assignments to handsets
135. enses mentioned in iv you must comply with the terms of that license If you license the Adaptation under the terms of any of the licenses mentioned in i ii or iii the Applicable License you must comply with the terms of the Applicable License generally and the following provisions 1 You must include a copy of or the URI for the Applicable License with every copy of each Adaptation You Distribute or Publicly Perform II You may not offer or impose any terms on the Adaptation that restrict the terms of the Applicable License or the ability of the recipient of the Adaptation to exercise the rights granted to that recipient under the terms of the Applicable License 111 You must keep intact all notices that refer to the Applicable License and to the disclaimer of warranties with every copy of the Work as included in the Adaptation You Distribute or Publicly Perform IV when You Distribute or Publicly Perform the Adaptation You may not impose any effective technological measures on the Adaptation that restrict the ability of a recipient of the Adaptation from You to exercise the rights granted to that recipient under the terms of the Applicable License This Section 4 b applies to the Adaptation as incorporated in a Collection but this does not require the Collection apart from the Adaptation itself to be made subject to the terms of the Applicable License If You Distribute or Publicly Perform the Work or any Adaptations or Coll
136. ent to distribute the source code even though third parties are not compelled to copy the source along with the object code 5 A program that contains no derivative of any portion of the Library but is designed to work with the Library by being compiled or linked with it is called a work that uses the Library Such a work in isolation is not a derivative work of the Library and therefore falls outside the scope of this License However linking a work that uses the Library with the Library creates an executable that is a derivative of the Library because it contains portions of the Library rather than a work that uses the library The executable is therefore covered by this License Section 6 states terms for distribution of such executables When a work that uses the Library uses material from a header file that is part of the Library the object code for the work may be a derivative work of the Library even though the source code is not Whether this is true is especially significant if the work can be linked without the Library or if the work is itself a library The threshold for this to be true is not precisely defined by law If such an object file uses only numerical parameters data structure layouts and accessors and small macros and small inline functions ten lines or less in length then the use of the object file is unrestricted regardless of whether it is legally a derivative work Executables containing this
137. ents 18 CHAPTER 2 INTRODUCTION TO OPENBTS APPLICATION SUITE smqueue RFC 3428 SMS Processor Transcevier Radiomodem UDP SIP SIP SMTP a SIP subscriber registry SIP SQL Database Server HTTP S Protocol Processor SIP RTP SIP RTP AX SIP IAX Softswitch SIP HTTP S Unit 1 SIP SIP RTP OpenBTS GSM SIP Protocol Processor UDP Transcevier Radiomodem Unit 2 Figure 2 2 Two access points with unit 1 providing servers for both Chapter 3 Getting to Know Your OpenBTS System 3 1 Accessing the System 19 3 2 Starting and Stopping Applications o e 2 20 3 3 OpenBTS Command Line Interface CLI ooooo 20 331 Starting and Stopping the CL s s a 00 844 464 ao ae SG bee eas 20 332 Using the Cel 2542434442858 4 rd eA hee oe bd GRR aS 21 3 3 3 Using the CLI to Access a Remote Node 0 o 23 3 3 4 Using the CLI in Development o eee ee 23 3 4 Using the OpenRANUI 2 eee ee 24 3 4 1 Starting and Stopping Applications of OpenBTS Suite 24 3 4 2 Configuring Applications of OpenBTS Suite o o 24 3 43 Managing Subscribers e 25 3 4 4 Monitoring the Node e 25 3 5 Databases coso ee ew a R A A Ee ee 25 3 0 Folder Structure ss s acs am a od ke a ee ae eS 25 Sf Logg ci Po Ree dae he ee ee Ob tee oa ae 26
138. eo Range 0 vo 00 000 s2220 NETWORKS OpenBTS Application Suite Release 4 0 User Manual Revision date April 15 2014 Copyright 2011 2014 Range Networks Inc This document is distributed and licensed under a Creative Commons Attribution ShareAlike 3 0 Unported License Contents 1 General Information 1 1 Scope and Audience 1 2 License and Copyright scusi mm ess erica ek ee Eo ai 1 3 Disclaimers 2020 0 cee Ya BE eC NG ee ace ae bed E Be 2 Ge i ee ed 1 4 Source Code Availability oo sa Bw Swe e Eee We ee EE ate a oe ee a E 15 Abbreviations eq sara eee a A Be ae we ee dl ee 2 OP e a ed L6 References si tess p gb eh ee ew Soe Oe OO a ee a Me ae be ee 1 7 Contact Information Le Support c 4 to A bw eee af he a oe a we eee 2 Introduction to OpenBTS Application Suite Dalla Key Programe hus ce ae eh ey O 2 2 Network Organization a s 3 actor e See eR GS a aw GUO ede be ee Re ee i 3 Getting to Know Your OpenBTS System Sa Accessing the System o r ph da a BE EG Boe a Se Se ee ee g 3 2 Starting and Stopping Applications lt lt 2 4 2 0 8a a Yor boa ok Ae ee BS we a 3 3 OpenBTS Command Line Interface CLI 2266044000 Oe eae wee ee OR ea es 3 4 Using the OpenRANUl oc aoh 4 44 4 464 Bare Eee bw eee be ha ae et 25 e scat he ee ae Gas etn we O a et ee se A OG Folder SINUELIAS osman a i 1 ct bo a a ee Ee SS Be eee eS 3A a2 ore cheek A A Bese Ge be od Go ae Gee ee ee Bee 4 OpenBTS Data Ta
139. eo Ged es 127 E 5 4 Email Notifications poed oso e 128 Mobility is the ability to transfer an MS s service as it moves from one BTS unit to another in a multi BTS network so that inbound calls for that MS get routed to it correctly Mobility is one of the defining features of a cellular network Handover is the transfer of an active call from one BTS unit to the other OpenBTS supports both mobility and handover E 1 How Mobility Works E 1 1 How Mobility Works In GSM There are two mobility mechanisms in GSM that are implemented in OpenBTS the location area and the neighbor list 118 E 1 HOW MOBILITY WORKS 119 Location Areas A GSM network is divided into geographical regions called location areas each one typically served by a single BSC Every BTS broadcasts its location area code LAC on the BCCH In OpenBTS the LAC is controlled with the GSM Identity LAC configuration parameter which is dynamic and can be altered in real time An MS performs a location updating request whenever it enters a new location area When an MS is paged for an inbound call the paging request is sent to all of the cells in the location area in which an MS is registered The implication here is that the GSM core network does not need to know the specific cell that is serving an MS only its location area However if every cell in the network has a different LAC the MS will perform a location updating request every time it move
140. eral Public License Of course the commands you use may be called something other than show w and show c they could even be mouse clicks or menu items whatever suits your program You should also get your employer if you work as a programmer or your school if any to sign a copyright disclaimer for the program if necessary Here a sample alter the names Yoyodyne Inc hereby disclaims all copyright interest in the program Gnomovision a program to direct compilers to make passes at assemblers written by James Hacker lt signature of Ty Coon gt 1 April 1989 Ty Coon President of Vice That s all there is to it G 3 GNU General Public License v 2 GNU GENERAL PUBLIC LICENSE Version 2 June 1991 G 3 GNU GENERAL PUBLIC LICENSE V 2 145 Copyright C 1989 1991 Free Software Foundation Inc 51 Franklin Street Fifth Floor Boston MA 02110 1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Preamble The licenses for most software are designed to take away your freedom to share and change it By contrast the GNU General Public License is intended to guarantee your freedom to share and change free software to make sure the software is free for all its users This General Public License applies to most of the Free Software Foundation s software and to any other program whose authors commit to using it Some other Free So
141. erimental values for existing configuration keys The command is most commonly used to set custom log levels for individual system components for trou bleshooting purposes as shown in the following example The user wishes to log more Layer 3 Call Control information OpenBTS gt rawconfig Log Level CallControl cpp INFO defined new config Log Level CallControl cpp as INFO OpenBTS gt rawconfig Log Level CallControl cpp Log Level CallControl cpp INFO Note The unconfig and rmconfig commands can also be used on these custom key values OpenBTS gt unconfig Log Level CallControl cpp Log Level CallControl cpp disabled OpenBTS gt rawconfig Log Level CallControl cpp Log Level CallControl cpp disabled OpenBTS gt rmconfig Log Level CallControl cpp Log Level CallControl cpp removed from the configuration table OpenBTS gt rawconfig Log Level CallControl cpp OpenBTS gt C 21 REGPERIOD COMMAND 111 C 21 regperiod Command The regperiod command prints or sets the registration timer GSM T3212 and SIP registration period OpenBTS gt regperiod T3212 is O minutes SIP registration period is 90 minutes In order to modify both parameters type regperiod GSM SIP where GSM is the value of the GSM Timer T3212 parameter in minutes and SIP is the value of SIP RegistrationPeriod also in mnutes OpenBTS gt regperiod 60 72 OpenBTS gt config GSM Timer T3212 GSM Timer T3212 60
142. es the full BSIC GSM Radio PowerManager NumSamples Number of samples averaged by the output power control loop GSM Radio PowerManager Period Power manager control loop master period in milliseconds GSM Radio PowerManager SamplePeriod Sample period for the output power control loop in mil liseconds GSM Radio PowerManager TargetT3122 Target value for T3122 the random access hold off timer for the power control loop GSM Radio RxGain Receiver gain setting in dB Ideal value is dictated by the hardware 47 dB for RAD1 This database parameter is static but the receiver gain can be modified in real time with the CLI rxgain command GSM Timer T3103 Handover timeout in milliseconds GSM 04 08 11 1 2 This is the timeout for a handset to seize a channel during handover GSM Timer T3105 Milliseconds for handset to respond to physical information GSM 04 08 11 1 2 GSM Timer T3113 Paging timer T3113 in milliseconds This is the timeout for a handset to respond to a paging request This should usually be the same as SIP Timer B in your VolP network GSM Timer T3122Max Maximum allowed value for T3122 the RACH holdoff timer in milliseconds This timer is sent to the MS with a granularity of seconds in the range 1 255 GSM 4 08 10 5 2 43 B 1 OPENBTS PARAMETERS 97 GSM Timer T3122Min Minimum allowed value for T3122 the RACH holdoff timer in milliseconds GSM 4 08 10 5 2 43
143. ess and port of the proxy to be used for text messaging This is smqueue for example SIP Proxy Speech The hostname or IP address and port of the proxy to be used for normal speech calls This is Asterisk for example SIP Proxy USSD The hostname or IP address and port of the proxy to be used for USSD or testmode to test by reflecting USSD messages back to the handset To disable USSD execute unconfig SIP Proxy USSD SIP RFC3428 NoTrying Send 100 Trying response to SIP MESSAGE even though that violates RFC 3428 SIP SMSC The SMSC handler in smqueue This is the entity that handles full 3GPP MIME encapsulted TPDUs If not defined use direct numeric addressing The value should be disabled with unconfig SIP SMSC if SMS MIMEType is text plain or set to smsc ifSMS MIMEType is application vnd 3gpp SMS FakeSrcSMSC Use this to fill in L4 SMSC address in SMS delivery B 1 OPENBTS PARAMETERS 93 SMS MIMEType This is the MIME Type that OpenBTS will use for RFC 3428 SIP MESSAGE payloads Valid values are application vnd 3gpp sms and text plain TRX Args Extra arguments for the Transceiver TRX IP IP address of the transceiver application B 1 3 Developer Factory Parameters These parameters should only be changed by when developing new code CLI SocketPath Path for Unix domain datagram socket used for the OpenBTS console interface Control C
144. eters are stored in SIPAuthServe Configuration Table located at etc OpenBTS sipauths The schema is identical to the OpenBTS Configuration Table discussed in section 4 1 B 3 1 Customer Site Parameters None defined at this time B 3 2 Customer Tuneable Parameters These parameters can be changed to optimize your site e Log Alarms Max Maximum number of alarms to remember inside the application e Log Level Default logging level when no other level is defined for a file e SubscriberRegistry A3A8 Path to the program that implements the A3 A8 algorithm e SubscriberRegistry Port Port used by the SIP Authentication Server NOTE In some older releases pre 2 8 1 this is called SIP myPort e SubscriberRegistry db The location of the sqlite3 database holding the subscriber registry B 3 3 Developer Factory Parameters These parameters should only be changed by when developing new code e Control NumSQLTries Number of times to retry SQL queries before declaring a database access failure e Log File Path to use for textfile based logging By default this feature is disabled To enable specify an absolute path to the file you wish to use eg tmp my debug log Appendix C The Command Line Interface CLI Reference C 1 C 2 C 3 C 4 C 5 C 6 C 7 C 8 C 9 C 10 C 11 C 12 C 13 C 14 C 15 C 16 C 17 C 18 C 19 C 20 C 21 C 22 C 23 C 24 C 25 C 26 alarms Command s s s sace aa moe
145. eters must be changed to fit your site e Control Emergency GatewaySwitch Gateway SIP switch for inbound calls from other networks This host is used to form the return path for emergency calls so it should be a host address that will route from your serving PSAP 85 86 APPENDIX B CONFIGURATION PARAMETERS e Control Emergency Geolocation If defined send this location as an RFC 4119 XML GEOPRIV object during SIP emergency call establishment Format is dd mm ss NS ddd mm ss EW e GSM Identity BSIC BCC GSM basestation color code lower 3 bits of the BSIC BCC values in a multi BTS network should be assigned so that BTS units with overlapping coverage do not share a BCC This value will also select the training sequence used for all slots on this unit e GSM Identity BSIC NCC GSM network color code upper 3 bits of the BSIC Assigned by your national regulator Must be distinct from NCCs of other GSM operators in your area e GSM Identity CI Cell ID 16 bits In some cases the last digit of the cell id represents the sector id A last digit of 0 is used for an omnidirectional antenna A last digit of 1 2 3 etc indicates a sector of the multi sector antenna Should be unique e GSM Identity LAC Location area code 16 bits values OxFFxx are reserved For multi BTS networks assign a unique LAC to each BTS unit This is not the normal procedure in conventional GSM networks but is the correct procedure in OpenBT
146. eue via SMS 2 This application interacts with the SIPAuthServe Section 6 1 and adds the new MS to the whitelist 3 The new subscriber power cycles the new MS to induce a new location update 4 The new MS now has service 6 2 3 Open Registration Open registration is a mode where all MSs are accepted for registration regardless of their authentication or provisioning status Depending on the configuration of Asterisk Chapter 6 and SMQueue Chapter 7 these unprovisioned MSs may be able to make telephone calls and send text messages To enable open registration set Control LUR OpenRegistration to a POSIX regular expression matching the IMSlIs that are to be accepted See examples below There is a second open registration parameter called Control LUR OpenRegistration Reject for re jecting IMSIs If open registration is not used Control LUR OpenRegistration is an empty string set with unconfig Control LUR OpenRegistration then this parameter is ignored If open registration Obviously such handsets cannot receive calls or text messages because until they are provisioned they have no assigned telephone numbers 6 2 PROVISIONING NEW SUBSCRIBERS 41 is on this parameter can be used to reject IMSIs even if they match the regular expression specified in Control LUR OpenRegistration Here are some sample regular expressions for Control LUR OpenRegistration and Control LUR OpenRegistrati
147. f running the Program is not restricted and the output from the Program is covered only if its contents constitute a work based on the Program independent of having been made by running the Program Whether that is true depends on what the Program does 1 You may copy and distribute verbatim copies of the Program s source code as you receive it in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty keep intact all the notices that refer to this License and to the absence of any warranty and give any other recipients of the Program a copy of this License along with the Program You may charge a fee for the physical act of transferring a copy and you may at your option offer warranty protection in exchange for a fee 2 You may modify your copy or copies of the Program or any portion of it thus forming a work based on the Program and copy and distribute such modifications or work under the terms of Section 1 above provided that you also meet all of these conditions a You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change b You must cause any work that you distribute or publish that in whole or in part contains or is derived from the Program or any G 3 GNU GENERAL PUBLIC LICENSE V 2 147 part thereof to be licensed as a whole at no charge to all third parties under
148. f contains comments available to the operator at all times and repeated in this manual To change a dynamic configuration parameter in real time edit the table using one of the methods described at the beginning of this chapter The effect will be immediate although in progress transactions may continue to use the parameters with which they started E g A change in SIP Proxy Speech will not affect in progress telephone calls but any new calls will use the new proxy When changing a static configuration parameter the OpenBTS application must be restarted see section 3 2 for instructions in order for the change to take effect For optional parameters an empty string is a valid value and normally means that the parameter has been disabled or is configured automatically To set a parameter to an empty value use the unconfig command in the CLI The complete list of configuration parameters is provided in Appendix B The configuration parameters of particular importance are covered in the sections below 4 3 TMSI TABLE 29 4 3 TMSI Table To reduce dependence on a backhaul link OpenBTS tracks TMSls internally on a per cell basis OpenBTS allocates a TMSI in the TMSI table for every MS that sends a Location Updating Request whether the MS is allowed to register or not 1 To accomplish this OpenBTS tracks TMSI IMSI relationships in an sqlite3 database table called the TMSI ta ble with the default location at var run
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153. ge test gt sendsms lt IMSI gt lt sourceAddress gt lt message text gt The difference between the two is that sendsimple operates by sending an RFC 3428 SIP MESSAGE packet to the OpenBTS SIP port while sendsms operates directly in the SMS control layers of OpenBTS C 25 sgsn Command The sgsn command provides sub commands to control SGSN GGSN sub system The syntax is sgsn subcommand lt options gt The following sub commands are currently available e free imsiltlli id e help print help e list imsil t11i id print the list of current GPRS sessions tracked by the SGSN normally one per GPRS attached handset C 26 shutdown Command The shutdown command shuts down the OpenBTS and transceiver processes If an argument is provided the command will wait up to the given number of seconds for in progress calls and transactions to clear before exiting During this wait time no new calls or transactions will be allowed to start The shutdown command with no arguments exits the OpenBTS process immediately In embedded configurations from Range OpenBTS runs as an upstart serice and therefore the OpenBTS GSM stack and its transceiver will restart automatically after a shutdown However the CLI would not be able to reconnect to the new instance of OpenBTS and will require a restart This is an expected behavior C 27 STATS COMMAND 113 C 27 stats Command Prints perform
154. gency Source User SIP identity to use if no IMSI is available IMS specifies anonymous but other values might be more useful depending on your configuration e Control GSMTAP GPRS Capture GPRS signaling and traffic at L1 L2 interface via GSMTAP OPENBTS PARAMETERS 87 Control GSMTAP GSM Capture GSM signaling at L1 L2 interface via GSMTAP Control GSMTAP TargetIP Target IP address for GSMTAP packets the IP address of Wireshark if you use it for real time traces Control LUR 404RejectCause Reject cause for location updating failures for phones that fail authen tication The SIP result code from the Registrar in this case is 404 Reject causes come from GSM 04 08 10 5 3 6 Reject cause 0x02 or 0x04 is usually the right one Control LUR AttachDetach Use attach detach procedure This will make initial LUR more prompt It will also cause an un registration if the handset powers off and really heavy LUR loads in areas with spotty coverage Range Networks strongly recommends setting this to 1 Control LUR FailMode Action to take after registration failure due to network failure error in Reg istrar or other unexpected error This does not apply to regular authorization failure handled by other config options If ACCEPT the handset is authorized for service If FAIL the handset is denied service If OPEN the open registration procedure is applied Control LUR FailedRegistration Message Send this text message f
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158. he commercial release of OpenBTS supports the emergency call transaction and presents the call to a SIP router at a configurable extension For speed and reliability OpenBTS always uses very early assignment VEA for emergency call establishment in Um regardless of the setting of the Control VEA configuration parameter in OpenBTS 6 3 1 What the User Dials There are several standard emergency numbers used in different parts of the world 911 112 999 etc When a mobile phone user enters one of these dialing codes into an MS it is not treated as a dialed telephone number Instead it is a special code that puts the MS into a special emergency call mode Most GSM MSs will recognize the dial strings 911 999 or 112 as an emergency call regardless of where the MS was sold or where it is being used When the emergency call is delivered to the BTS the actual number dialed by the user is not reported by the MS only the fact that an emergency call has been requested The routing of an emergency call is configured into the network and has nothing to do with the number actually dialed by the user as long as the user dials a recognizable emergency number When OpenBTS receives an emergency call setup request it presents the inbound call to its designated emer gency call proxy switch or PBX which may be different from the proxy switch or PBX used for normal speech calls The SIP message headers for the INVITE message are formatted accord
159. he corresponding slides let you enable and disable the components Click on Save to confirm your action To minimize the node panel click on done 3 4 2 Configuring Applications of OpenBTS Suite The Configuration panel provides easy access to the primary configuration parameters of the OpenBTS suite components namely OpenBTS SMQueue SIPAuthServe and RangeSIMd For ease of use they are grouped into basic and advanced Note The OpenRANUI does not provide access to development factory or custom parameters Use the CLI to review and or change them Indicators on the left show the status of these parameters e white indicator means that the parameter value is valid e yellow indicator means that the parameter has been modified but is not saved yet e red indicator means an incorrect value incorrect values cannot be saved and e grey indicator means that the parameter is set to the default value To reset a parameter to its default value move your mouse over the default area and click on it 3 5 DATABASES 25 The audit panel of the OpenRANUI provides an audit of the current OpenBTS configuration It can help detect problems in the setup though not all warning messages would necessarily point to a problem In a multi node configuration the audit panel would also do a cross node check of values that need to be coordinated in the network 3 4 3 Managing Subscribers The Subscribers panel
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161. ibrary s complete source code as you receive it in any medium provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty keep intact all the notices that refer to this License and to the absence of any warranty and distribute a copy of this License along with the Library You may charge a fee for the physical act of transferring a copy and you may at your option offer warranty protection in exchange for a fee 2 You may modify your copy or copies of the Library or any portion of it thus forming a work based on the Library and copy and distribute such modifications or work under the terms of Section 1 above provided that you also meet all of these conditions a The modified work must itself be a software library b You must cause the files modified to carry prominent notices stating that you changed the files and the date of any change c You must cause the whole of the work to be licensed at no charge to all third parties under the terms of this License d If a facility in the modified Library refers to a function or a table of data to be supplied by an application program that uses the facility other than as an argument passed when the facility is invoked then you must make a good faith effort to ensure that in the event an application does not supply such function or table the facility still operates and performs whatever part of its purpose remain
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163. ich starts gprs service gprs testbsn Test bsnj i frame number functions gprs testmsg Test message functions C 11 handover Command The handover command attempts a handover of a particular IMSI to a neighbor specified by its ip address The parameters are as follows handover imsi neighbor C 12 help Command The help command provides a list of all commands available in the CLI help followed by a command name provides help on that command For example OpenBTS gt help cellid cellid MCC MNC LAC CI get set location area identity MCC MNC LAC and cell ID CI C 13 load Command Give the current BTS load in terms of active channels and queue lengths load The results mean e SDCCH load The number of active SDCCHs out of the total available e TCH F load The number of active TCH Fs out of the total available C 14 MEMSTAT COMMAND 109 e AGCH PCH load The number of queued messages awaiting transmission on the AGCH and PCH e Paging table size The number of MSs currently being paged e Transactions TMSIs The number of active transactions in the BTS and the size of the TMSI table e 13122 The current value of the T3122 hold off timer in seconds See Section 5 1 for details e current PDCHs GRPS active channels e utilization GPRS channel utilization C 14 memstat Command The development command used for internal testing It prints memor
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165. ility local7 OpenBTS and its allies with numeric severity values of 1 or lower ALERT and EMERGENCY e Regardless of log activity the BTS unit will send no more than one email message every 15 minutes The typical email delivery in this example is From openbts Subject alarm on unit_24 Date October 5 2011 7 53 46 PM PDT To support mynoc com ALERT 3079411408 OpenBTS cpp 141 main OpenBTS starting ver P2 8TRUNK build date Oct 5 2011 Appendix F Test Procedures F 1 Test SIM Procedures es 130 Fila Tests with the TestiSiM 9440 46 cc ara a a aes 131 F 2 Testing with Open Registration o eee ee ee ee 132 F2 1 Interference Prevention lt cs et 0654 ria a bo a a 132 F 2 2 Test Procedures co nioma e a e a A a k a a E oe e a a i aA 132 The default configuration of a Range Networks factory installed OpenBTS Release 4 0 system includes an Asterisk configuration to support testing of OpenBTS Asterisk the SIP authorization server SIPAuthServe Subscriber Registry and SMQueue as a system In order to test the system you need two SIM cards with known IMSI numbers and unlocked handsets that operate in the GSM band specified by the GSM Radio Band parameter of your OpenBTS system F 1 Test SIM Procedures In order to perform these test procedures your SIM cards must be provisioned in your OpenBTS system See section 6 2 on how to provision pre existing SIMs If you purchased the Rang
166. imer T3212 period in minutes Should be a factor of 6 Set to 0 to disable periodic registration Should be smaller than SIP registration period Log Alarms Max Maximum number of alarms to remember inside the application Log Level Default logging level when no other level is defined for a file Peering Neighbor RefreshAge Seconds before refreshing parameters from a neighbor Peering NeighborTable Path File path for neighbor information database Peering Port The UDP port used by the peer interface for handover RTP Range Range of RTP port pool Pool is RTP Start to RTP Range 1 RTP Start Base of RTP port pool Pool is RTP Start to RTP Range 1 SIP DTMF RFC2833 Use RFC 2833 RTP event signalling for in call DTMF SIP DTMF RFC2833 PayloadType Payload type to use for RFC 2833 telephone event packets SIP DTMF RFC2976 Use RFC 2976 SIP INFO method for in call DTMF SIP Local IP IP address of the OpenBTS machine as seen by its proxies If these are all local this can be localhost SIP Local Port IP port that OpenBTS uses for its SIP interface SIP Proxy Emergency The hostname or IP address and port of the proxy to be used for emergency calls SIP Proxy Registration The hostname or IP address and port of the proxy to be used for registration and authentication This should normally be the subscriber registry SIP interface not Asterisk SIP Proxy SMS The hostname or IP addr
167. individual MS capabilities Most modern MS devices support up to five total slots in some combination of 1 4 slots each on downlink and or uplink Some common multislot classes for consumer devices that are also supported by OpenBTS are given in Table A 2 The default multi slot assignment is specified in the config parameters and is 2 slots up 3 slots down This is the fastest configuration for most purposes especially web browsing Another common configuration is 2 slots up 2 slots down which is almost as fast but packs MS into ARFCNs better While it is possible to change the default to 1 slot up 4 slots down it is not recommended Counter intuitively browsers send a large amount of IP traffic in the uplink direction sometimes more than in the downlink direction so using a 1 up 4 down is usually much slower than the default Table A 2 Common GPRS multislot classes giving maximum uplink and downlink multislot capabilities Mutislot Class Max Rx Max Tx Max Sum Rx Tx 1 1 1 2 2 2 1 3 3 2 2 3 4 3 1 4 5 2 2 4 6 3 2 4 7 3 3 4 8 4 1 5 9 3 2 5 10 4 2 5 11 4 3 5 12 4 4 5 GPRS Uplink Power Control GPRS as implemented by OpenBTS uses open loop unlink power control where the handset sets its transmitted power based on the RSSI of the network s downlink signal assuming roughly equal uplink and downlink path losses The algorithm used to set the transmitted power is
168. ing ANY private IP address For more complex network topologies firewalls on the BTS units themselves must be configured to prevent such access The current GGSN internal firewall settings are logged at the NOTICE level when GPRS starts NAT Programming Whether a BTS is using a dynamic or static IP address the following commands can be used to configure the NAT Note that the last command implies the use of eth0 interface Should your system use a different one the parameter needs to be set accordingly sudo modprobe iptable_nat sudo iptables t nat F sudo iptables t nat A POSTROUTING o ethO j MASQUERADE To view the current NAT settings the command is sudo iptables t nat list Once you confirm that the NAT settings are correct they need to be saved so that they would still be in effect after a reboot sudo iptables save gt iptables rules sudo mv iptables rules etc OpenBTS The settings are then being loaded in etc network inferfaces at system boot A 4 3 Radio Resource Management and Performance in GPRS GPRS Registration This is the process whereby the MS Mobile Station or cell phone informs the SGSN component of GPRS of its IMSI identity Each MS must register before it can use IP services The GPRS registration process is separate from the GSM registration process and an MS will usually hold two registrations one for CS Circuit Switched i e voice services and another for PS Packet Switched or In
169. ing authors For the avoidance of doubt You may only use the credit required by this Section for the purpose of attribution in the manner set out above and by exercising Your rights under this License You may not implicitly or explicitly assert or imply any connection with sponsorship or endorsement by the Original Author Licensor and or Attribution Parties as appropriate of You or Your use of the Work without the separate express prior written permission of the Original Author Licensor and or Attribution Parties Except as otherwise agreed in writing by the Licensor or as may be otherwise permitted by applicable law if You Reproduce Distribute or Publicly Perform the Work either by itself or as part of any Adaptations or Collections You must not distort mutilate modify or take other derogatory action in relation to the Work which would be prejudicial to the Original Author s honor or reputation Licensor agrees that in those jurisdictions e g Japan in which any exercise of the right granted in Section 3 b of this License the right to make Adaptations would be deemed to be a distortion mutilation modification or other derogatory action prejudicial to the Original Author s honor and reputation the Licensor will waive or not assert as appropriate this Section to the fullest extent permitted by the applicable national law to enable You to reasonably exercise Your right under Section 3 b of this License right to make Adaptations but
170. ing on the level of economic development being higher in more developed areas The Erlang capacity of the BTS is dependent on its allowed blocking probability which is the probability that a call will be rejected due to congestion during the busy hour Blocking probabilities of 2 3 are typical in public cellular networks Table A 1 shows Erlang capacities for BTS units in a typical configuration of 7 TCH F per ARFCN at a blocking probability of 3 Note that Erlangs ARFCN increases for larger systems due to increased trunking efficiency All other things being equal a single 2N ARFCN BTS will have more capacity than 2 N ARFCN units 1t s the busy hour Do you know your offered load For example take the number of minutes per month you talk on the phone in a month and divide by 14400 to get a conservative estimate of your own offered load 72APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS Table A 1 Speech calling and service capacities of GSM systems BTS channels Erlangs subscribers subscribers ARFCNs TCH F 3 blocking 0 01 E sub 0 05 E sub 1 7 3 25 325 65 2 14 8 80 880 176 3 21 14 9 1490 298 4 28 21 2 2120 424 5 35 27 7 2720 554 Registration Load for Camped Phones The system load from keeping idle phones on the cell is due to their registration activity A single SDCCH can process about 15 authenticated registrations pe
171. ing to 3GPP 24 229 Section 4 and include an encoding of the full cell identity and optionally the geocoordinates of the BTS site Most call setup operations in OpenBTS are non queuing and calls are rejected immediately if no channel is available Emergency calls are an exception to this behavior and may be queued for a few seconds waiting for resources to come available Furthermore if an emergency call is placed in a congested cell OpenBTS will terminate the longest running non emergency call in the cell to free a channel for the emergency call 44 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK 6 3 2 Configuring OpenBTS to Support Emergency Calls To support emergency calls in OpenBTS the following must be configured e GSM RACH AC Bit 10 of GSM RACH AC must be cleared to indicate that the network supports emergency calls e SIP Proxy Emergency This parameter specifies the IP address and port of the proxy switch or PBX used for emergency calls e Control Emergency All of the parameters in this group must be defined with the exception of Control Emergency Geolocation which is optional See Section 4 2 for details about these parameters All of these parameters are dynamic and can be set or changed at any time without disrupting service 6 4 Connecting to a VoIP Carrier In many VoIP installations the operator will use a commercial VoIP carrier to route calls to and from the PSTN In some c
172. ingers musicians dancers and other persons who act sing deliver declaim play in interpret or otherwise perform literary or artistic works or expressions of folklore ii in the case of a phonogram the producer being the person or legal entity who first fixes the sounds of a performance or other sounds and iii in the case of broadcasts the organization that transmits the broadcast Work means the literary and or artistic work offered under the terms of this License including without lim itation any production in the literary scientific and artistic domain whatever may be the mode or form of its expression including digital form such as a book pamphlet and other writing a lecture address sermon or other work of the same nature a dramatic or dramatico musical work a choreographic work or entertainment in dumb show a musical composition with or without words a cinematographic work to which are assimilated works expressed by a process analogous to cinematography a work of drawing painting architecture sculpture engraving or lithography a photographic work to which are assimilated works expressed by a process analogous to photography a work of applied art an illustration map plan sketch or three dimensional work relative to geography topography architecture or science a performance a broadcast a phonogram a compilation of data to the extent it is protected as a copyrightable work or a work performed by a variety or circus
173. ion 2 1 4 SIP router PBX OpenBTS uses a SIP router or PBX to perform the call control functions that would normally be performed by the mobile switching center in a conventional GSM network although in most network configurations this switching function is distributed over multiple switches These switches also provide transcoding services As of OpenBTS Release 4 0 the standard SIP router is Asterisk 11 OpenBTS has been used with VolP PBX and switch applications other than Asterisk however Range does not normally support these configurations 16 CHAPTER 2 INTRODUCTION TO OPENBTS APPLICATION SUITE For more information on Asterisk itself a good resource is the book Asterisk The Future of Telephony by Jim Van Meggelen Jared Smith and Leif Madsen from O Reilly Publishing ISBN 0 596 00962 3 See Chapter 6 for information about integration between OpenBTS and Asterisk 2 1 5 SIPAuthServe An application that implements Subscriber Registry the database of subscriber information that replaces both the Asterisk SIP registry and the GSM Home Location Register HLR found in a conventional GSM net work OpenBTS also relies on Asterisk for any transcoding functions See Chapter 6 for information about SIPAuthServe Subscriber Registry and their integration with OpenBTS and Asterisk 2 2 Network Organization In the simplest network with a single access point all of the applications in the suite run inside the access point on the sam
174. ion on roaming support please contact Range Networks Section 1 7 6 2 6 The Security of SIMs The integrity of the GSM challenge response authentication is dependent on the secrecy of Ki which in OpenBTS systems should be known only within the SIM and the Subscriber Registry In a specification compliant SIM Ki cannot be read directly only tested through the RAND SRES process If Ki cannot be extracted from the SIM then the SIM cannot be fully cloned since a clone with the wrong Ki will generate the wrong SRES for a given RAND At least this is how it is supposed to work COMP128v1 and SIM Cloning The GSM specifications do not define specific algorithms for A3 amp A8 but early specifications did offer an example of a combined A3 A8 algorithm called COMP128 since renamed to COMP128v1 As a result of the publication of this example COMP128v1 was used in most early SIMs even though that was not the intention of the specification authors Since its original publication COMP128v1 has been compromised It is well known that it is possible to compute Ki from a COMP128v1 based SIM given several thousand RAND SRES pairs This means that it is possible to build a SIM cloning system that extracts the IMSI and Ki from a COMP128v1 SIM by running several thousand cycles of COMP128v1 with different RAND inputs and then programming the IMSI and extracted Ki into a blank SIM The cracking process takes a few hours but once Ki is known new clones can
175. irectly using SQL syntax in real time For offline editing sqlite3 can export SQL code to a text file with the dump command The text can then be edited and reimported with read Refer to sqlite3 manual for further details Please note however that this method of manipulating databases is not safe and may corrupt your databases Understanding of OpenBTS data structures sqlite3 database journaling and general SQL principles is required lt is recommended that a reserve copy of a configuration database is made prior to editing 4 2 The Configuration Table The parameters that control the OpenBTS application are stored in a database table called the configuration table located at etc OpenBTS OpenBTS db Some parameters are dynamic meaning that a parameter change will have an immediate effect Some of these parameters are static and changes to them do not take effect until OpenBTS is restarted Some of these static parameters are matched to the hardware of a specific implementation and should not be changed at all Comments within the configuration database describe each parameter and under what conditions it can be changed Flags within the database schema indicate which parameters are static The schema for the configuration table is CREATE TABLE CONFIG KEYSTRING TEXT UNIQUE NOT NULL VALUESTRING TEXT STATIC INTEGER DEFAULT O OPTIONAL INTEGER DEFAULT O COMMENTS TEXT DEFAULT Note that the database itsel
176. ists exceptions to the Range copyright acquired under FOSS licenses and describes OpenBTS compliance with those licenses LGPL Compliance The following publicly available packages are linked dynamically by applications in the OpenBTS suite under LGPL licenses e UnixODBC Public distribution available from unixodbc org License is GNU Lesser General Public License V2 1 e libc6 Public distribution available from License is GNU Lesser General Public License v 2 1 e libortp8 Public distribution available from linphone org License is GNU Lesser General Public License v 2 1 e libusb 1 0 0 dev Public distribution available from libusb org License is GNU Lesser General Public License v 2 1 e libzmq Public distribution available from zeromq org License is GNU Lesser General Public License v 3 In each case OpenBTS uses the public distribution without modification GPL Compliance The following applications are distributed in Range Networks products and used in association with OpenBTS under GPL licenses 10 CHAPTER 1 GENERAL INFORMATION Asterisk 11 7 0 Public distribution available from asterisk org License is GNU General Public License v 2 DataTables plug in Public distribution available from datatables net The plug in is dual licensed under the GPLv2 license and a BSD 3 clause license libreadline dev Public distribution available from ftp gnu org License is GNU General Public License v 3 PNotify
177. l danger that patents applied to a free program could make it effectively proprietary To prevent this the GPL assures that patents cannot be used to render the program non free The precise terms and conditions for copying distribution and modification follow TERMS AND CONDITIONS O Definitions This License refers to version 3 of the GNU General Public License Copyright also means copyright like laws that apply to other kinds of works such as semiconductor masks The Program refers to any copyrightable work licensed under this License Each licensee is addressed as you Licensees and recipients may be individuals or organizations To modify a work means to copy from or adapt all or part of the work in a fashion requiring copyright permission other than the making of an exact copy The resulting work is called a modified version of the earlier work or a work based on the earlier work A covered work means either the unmodified Program or a work based on the Program To propagate a work means to do anything with it that without permission would make you directly or secondarily liable for 154 APPENDIX G FOSS LICENSES infringement under applicable copyright law except executing it on a computer or modifying a private copy Propagation includes copying distribution with or without modification making available to the public and in some countries other activities as well To convey a work means a
178. ll Location Updating The location updating step must be performed before any other test can proceed Location updating verifies the operation of e the OpenBTS GSM stack in the BTS e the air interface between the handset and BTS e SIPAuthServe and e the SIP interface between OpenBTS and SIPAuthServe The procedure is e Power up the BTS unit All of the required software will start automatically within two minutes e Turn on the handsets with the test SIMs e Within a few seconds the handsets should show service at network MCC 001 MNC 01 If the handsets are set for manual network selection choose network 001 01 e In the OpenBTS CLI the tmsis command Section C 29 should show the IMSI numbers of the corresponding SIM cards with a used value of just a few seconds 132 APPENDIX F TEST PROCEDURES MOC to Loopback MOC loopback verifies the signaling and media paths through OpenBTS and Asterisk e Be sure the handset s SIM card is registered and the handset shows service as in the location updating test e From the handset place a call to extension 2600 e The call should connect quickly to an echo test The echo latency will start large around 1 second but decrease quickly as the jitter buffers adapt MOC to Another Handset The MOC to handset test exercises MOC signaling more completely than the MOC to loopback test e Be sure the phones are registered and show service as in the location updating tes
179. ll respond with something like this code 200 data release 4 0 0 8025 GPRS C built Mar 19 2014 rev8026 CommonLibs rev8010 The following is an example of setting an SMQueue parameter target smqueue command config action update key SIP myIP2 value 192 168 0 22 The response is 59 60 CHAPTER 10 NODEMANAGER code 204 dirty 0 Here we read the value of the GSM Radio CO parameter in OpenBTS target openbts command config action read key GSM Radio Band The response is code 200 data defaultValue 900 description The GSM operating band Valid values are 850 for GSM850 900 for PGSM900 1800 for DCS1800 and 1900 for PCS1900 For non multiband units this value is dictated by the hardware and should not be changed key GSM Radio Band scope 2 Static true type multiple choice units validValues 850 GSM850 900 PGSM900 1800 DCS1800 1900 PCS1900 value 900 visibility customer warn a warning will be presented and confirmation required before changing this sensitive setting Note More examples available in file JSON_Interface txt in the NodeManager sources 1 10 2 Running NodeManager Queries OpenRanUl web interface which is available in the commercial version provides raw access to the NodeManager Access the web UI at http lt your_bts_ip_address gt r
180. ly only to part of the Program that part may be used separately under those permissions but the entire Program remains governed by this License without regard to the additional permissions When you convey a copy of a covered work you may at your option remove any additional permissions from that copy or from any part of it Additional permissions may be written to require their own removal in certain cases when you modify the work You may place additional permissions on material added by you to a covered work for which you have or can give appropriate copyright permission Notwithstanding any other provision of this License for material you add to a covered work you may if authorized by the copyright holders of that material supplement the terms of this License with terms a Disclaiming warranty or limiting liability differently from the terms of sections 15 and 16 of this License or b Requiring preservation of specified reasonable legal notices or author attributions in that material or in the Appropriate Legal Notices displayed by works containing it or c Prohibiting misrepresentation of the origin of that material or requiring that modified versions of such material be marked in reasonable ways as different from the original version or d Limiting the use for publicity purposes of names of licensors or authors of the material or e Declining to grant rights under trademark law for use of some trade names trademark
181. n Interface 0 0 e 2 o 37 6 1 4 Configuring Authentication o o 38 6 1 5 Intercepting Authentication 2 c es o 38 Provisioning New Subscribers o o 38 6 2 1 Using Pre existing SIMS 2 o 39 0 22 Whitelisting s s tae iat lo al a pleat ony cnt ae ae ae aa dhe he che da dd dar ots a a adh Ge 40 6 2 3 Opel Registration lt 22 2454 8a e ae Oe Be See ay ae aoe Bs 40 6 24 Generating Custom SIMs oe sype caa maea a pk Rh he ee doe 42 6 2 5 Roaming SIMS 43 eeta sa RRP Swe ee Pe See a 42 6 2 6 The Security of SIMS o s aas se aop a aR A ae ee G 42 Emergency Calls ias Rea ee ee a we Be ee Be E 43 6 3 1 What the User Dials p24 4044 4040 Pe ee badd a a EEE RG EGS 43 6 3 2 Configuring OpenBTS to Support Emergency Calls 44 Connecting to a VoIP Carrier o 4 2 44 Hybrid GSM SIP Transactions o o 45 6 5 1 Registration Location Updating oo ada a Peo ee ees 45 05 2 Call Control ei bee 4 04 2a RRA A Ee ee 45 Backhaul Capacity Considerations o et 45 6 6 1 Available Codes 2 pesa sago mai Re ee RD a RS 47 6 6 2 RTP IAX Overhead and Trunking e cacag e a pre e e a e y i a 47 35 36 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK One of the distinctive features of OpenBTS is the use a generic VoIP switch in place of
182. n OpenBTS Asterisk and the subscriber registry 1 Provision two handsets at two different telephone numbers using the procedure of the previous section 2 From one handset dial the telephone number of the other handset 3 The call should connect normally Appendix G FOSS Licenses G 1 Creative Commons License e 134 G 2 GNU General Public License v l o o es 139 G 3 GNU General Public License v 2 00 0 4 144 G 4 GNU General Public License v 3 o 152 G 5 GNU Lesser General Public License v 2 1 0 o eee ees 166 G 6 GNU Lesser General Public License v 3 o a 176 GI BSD Licenses salir ato a amp E ee a e e A 178 G 7 1 BSD License on the A5 1 Implementation 2 0 0 200000 0004 178 G 7 2 BSD License on Sparkline plug in ao aa a a 179 G 1 Creative Commons License License THE WORK AS DEFINED BELOW IS PROVIDED UNDER THE TERMS OF THIS CREATIVE COMMONS PUBLIC LICENSE CCPL OR LICENSE THE WORK IS PROTECTED BY COPYRIGHT AND OR OTHER APPLICABLE LAW ANY USE OF THE WORK OTHER THAN AS AUTHORIZED UNDER THIS LICENSE OR COPYRIGHT LAW IS PROHIBITED BY EXERCISING ANY RIGHTS TO THE WORK PROVIDED HERE YOU ACCEPT AND AGREE TO BE BOUND BY THE TERMS OF THIS LICENSE TO THE EXTENT THIS LICENSE MAY BE CONSIDERED TO BE A CONTRACT THE LICENSOR GRANTS YOU THE
183. n a text message to the autoprovisioning short code address If the requested number has an acceptable number of digits and is not already assigned to a user the autoprovisioning handler function will perform the steps described in Section 6 2 1 to provision the new user into the subscriber registry The autoprovisioning short code handler function is called shortcode register and is configured through the SC Register parameters in the SMQueue configuration table The short code for this function is stored in the SC Register Code parameter For autoprovisioning to work OpenBTS must also be configured with open registration enabled so that unprovi sioned MSs will show service and be capable of sending text messages The open registration welcome message can be a powerful way to advertise this feature especially if the return short code of the welcome message is the same as the short code of the autoprovisioning function See Section 6 2 3 for more information Info This short code handler generates a brief report of SMQueue status returned in a text message The imple menting function is called shortcode four_one one This short code handler can be configured with the SC Info parameters Debug Dump This short code is tied to an application which dumps debug information to the log It is defined in the SC DebugDump Code parameter and is intended for administrative development use Quick Check This sho
184. n be downloaded for free from the etsi org web site e GSM 03 38 Digital cellular telecommunications system Phase 2 Alphabets and language specific information e GSM 03 41 Digital cellular telecommunications system Phase 2 Technical realization of Cell Broad cast Service CBS e GSM 04 06 Digital cellular telecommunications system Phase 2 Mobile Station Base Station System MS BSS interface Data Link DL layer specification e GSM 04 08 Digital cellular telecommunications system Phase 2 Mobile radio interface layer 3 specification e GSM 05 02 Digital cellular telecommunications system Phase 2 Multiplexing and multiple access on the radio path e GSM 05 03 Digital cellular telecommunications system Phase 2 Channel coding e GSM 05 05 Digital cellular telecommunications system Phase 2 Radio transmission and reception e GSM 05 08 Digital cellular telecommunications system Phase 2 Radio subsystem link control e GSM 05 10 Digital cellular telecommunications system Phase 2 Radio subsystem synchronization e 3GPP TS 24 008 Digital cellular telecommunications system Phase 2 Universal Mobile Telecom munications System UMTS LTE Mobile radio interface Layer 3 specification Core network protocols Stage 3 e 3GPP 24 229 Digital cellular telecommunications system Phase 2 Universal Mobile Telecommuni cations System
185. n transaction table Upon receiving the GSM Handover Command the handset retunes to the new channel on BTS2 and begins sending the Handover Access repeatedly about 216 times per second at full power and with zero timing advance BTS2 responds as quickly as possible with the GSM Physical Information message which sets the new timing advance and transmit power level for the handover The handset responds with the GSM Handover Complete message to verify that all is well Moving the Call to a New IP Address Now that the handset is established on the radio channel BTS2 moves the handset s end of the call to the new IP address with a SIP re INVITE exhange Cleaning Up Once BTS2 receives the GSM Handover Complete message from the handset BTS2 sends the RPP IND HANDOVER message to BTS1 to indicate that the handover was successful and that the BTS resources originally used for the call can now be released BTS1 responds with ACK HANDOVER to close the transaction E 4 2 PBX amp Switch Support The SIP signaling used by OpenBTS for handovers is known to work with Asterisk 10 FreeSWITCH 1 1 and recent versions of yate Handover will not work with Asterisk versions prior to 10 Handover has not been tested with other SIP switch PBX products E 4 3 Configuring Handover The OpenBTS parameters related to handover and requiring configuration by the user are e GSM Neighbors This is the list of IP addresses of neighboring cells e GSM Handove
186. nable specify an absolute path to where the CDRs should be logged To disable execute unconfig CDRFile Log Alarms Max Maximum number of alarms to remember inside the application Log Level Default logging level when no other level is defined for a file B 2 SMQUEUE PARAMETERS 99 SC DebugDump Code Short code to the application which dumps debug information to the log Intended for administrator use SC Info Code Short code to the application which tells the sender their own number and registration status SC QuickChk Code Short code to the application which tells the sender the how many messages are currently queued Intended for administrator use SC Register Code Short code to the application which registers the sender to the system SC Register Digits Max The maximum number of digits a phone number can have SC Register Digits Min The minimum number of digits a phone number must have SC Register Digits Override Ignore phone number digit length checks SC Register Msg AlreadyA First part of message sent during registration if the handset is already registered followed by the current handset number SC Register Msg AlreadyB Second part of message sent during registration if the handset is already registered SC Register Msg ErrorA First part of message sent during registration if the handset fails to register followed by the attempted handset number SC Register Msg
187. nager SMSCB low rate data service In Range preconfigured systems all suite executables besides Asterisk are located in OpenBTS folder on the root partition 14 2 1 KEY PROGRAMS 15 2 1 Key Programs 2 1 1 OpenBTS The OpenBTS application contains e L1 TDM functions GSM 05 02 e L1 FEC functions GSM 05 03 e L1 closed loop power and timing controls GSM 05 08 and 05 10 e L2LAPDm GSM 04 06 e L3 radio resource management functions GSM 04 08 e 13 GSM SIP gateway for mobility management e 13 GSM SIP gateway for call control e L4 GSM SIP gateway for text messaging The general design approach of OpenBTS is not to implement any function above L3 or L4 so at L3 or L4 every subprotocol of GSM is either terminated locally or translated through a gateway to some other protocol for handling by an external application Similarly OpenBTS itself does not contain any speech transcoding functions above the L1 FEC parts 2 1 2 Transceiver The transceiver application performs the radiomodem functions of GSM 05 05 and manages the USB interface to the radio hardware The functions of the transceiver are described in Section A 1 1 2 1 3 SMQueue SMQueue is an RFC 3428 store and forward server that is used for text messaging in the OpenBTS system SMQueue is required to send a text message from one MS to another or to provide reliable delivery of text messages to an MS from any source See Chapter 7 for more informat
188. naling between BTS units and the remote party is SIP Signaling between BTS1 and BTS2 is RPP o 124 181 List of Tables 5 1 6 1 A 1 A 2 Maximum output power levels for GSM MSs From GSM 05 05 Section 4 1 1 34 Backhaul bandwidth for various codec trunking configurations All rates in kbit sec and assum ing 20 mS TramMliNGs e mbes wae bee Bek ee eS he ee eco Bh k e Se 48 Speech calling and service capacities of GSM systems 2 2 o a 72 Common GPRS multislot classes giving maximum uplink and downlink multislot capabilities 82 182
189. nd Maximum number of neighbors to send to handset in the neighbor list broadcast in the beacon GSM Ny1 Maximum number of repeats of the Physical Information Message during handover procedure GSM 04 08 11 1 3 GSM RACH AC Access class flags This is the raw parameter sent on the BCCH See GSM 04 08 10 5 2 29 for encoding Set to 0 to allow full access Set to 0x0400 to indicate no support for emergency calls GSM RACH MaxRetrans Maximum RACH retransmission attempts This is the raw parameter sent on the BCCH See GSM 04 08 10 5 2 29 for encoding GSM RACH TxInteger Parameter to spread RACH busts over time This is the raw parameter sent on the BCCH See GSM 04 08 10 5 2 29 for encoding GSM Radio ARFCNs The number of ARFCNs to use The ARFCN set will be CO CO 2 CO 4 etc GSM Radio Band The GSM operating band Valid values are 850 for GSM850 900 for PGSM900 1800 for DCS1800 and 1900 for PCS1900 For non multiband units this value is dictated by the hardware and should not be changed GSM Radio MaxExpectedDelaySpread Expected worst case delay spread in symbol periods roughly 3 7 us or 1 1 km per unit This parameter is dependent on the terrain type in the installation area Typical values are 1 for open terrain and small coverage areas a value of 4 is strongly recommended for large coverage areas This parameter has a large effect on computational requirements of the software radio values greater than
190. nd each file should have at least the copyright line and a pointer to where the full notice is found lt one line to give the program s name and a brief idea of what it does gt Copyright C 19yy lt name of author gt This program is free software you can redistribute it and or modify it under the terms of the GNU General Public License as published by the Free Software Foundation either version 1 or at your option 144 APPENDIX G FOSS LICENSES any later version This program is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU General Public License for more details You should have received a copy of the GNU General Public License along with this program if not write to the Free Software Foundation Inc 51 Franklin Street Fifth Floor Boston MA 02110 1301 USA Also add information on how to contact you by electronic and paper mail If the program is interactive make it output a short notice like this when it starts in an interactive mode Gnomovision version 69 Copyright C 19xx name of author Gnomovision comes with ABSOLUTELY NO WARRANTY for details type show w This is free software and you are welcome to redistribute it under certain conditions type show c for details The hypothetical commands show w and show c should show the appropriate parts of the Gen
191. ndividual works permit Inclusion of a covered work in an aggregate does not cause this License to apply to the other parts of the aggregate 6 Conveying Non Source Forms You may convey a covered work in object code form under the terms of sections 4 and 5 provided that you also convey the machine readable Corresponding Source under the terms of this License in one of these ways a Convey the object code in or embodied in a physical product including a physical distribution medium accompanied by the Corresponding Source fixed on a durable physical medium customarily used for software interchange b Convey the object code in or embodied in a physical product including a physical distribution medium accompanied by a written offer valid for at least three years and valid for as long as you offer spare parts or customer support for that product model to give anyone who possesses the object code either 1 a copy of the Corresponding Source for all the software in the product that is covered by this License on a durable physical medium customarily used for software interchange for a price no more than your reasonable cost of physically performing this conveying of source or 2 access to copy the Corresponding Source from a network server at no charge c Convey individual copies of the object code with a copy of the written offer to provide the Corresponding Source This alternative is allowed only occasionally and noncomme
192. ng for debugging such modifications if you also do each of the following a Give prominent notice with each copy of the Combined Work that the Library is used in it and that the Library and its use are covered by this License b Accompany the Combined Work with a copy of the GNU GPL and this license document c For a Combined Work that displays copyright notices during execution include the copyright notice for the Library among these notices as well as a reference directing the user to the copies of the GNU GPL and this license document d Do one of the following 0 Convey the Minimal Corresponding Source under the terms of this License and the Corresponding Application Code in a form suitable for and under terms that permit the user to recombine or relink the Application with a modified version of the Linked Version to produce a modified Combined Work in the manner specified by section 6 of the GNU GPL for conveying Corresponding Source 1 Use a suitable shared library mechanism for linking with the Library A 178 APPENDIX G FOSS LICENSES suitable mechanism is one that a uses at run time a copy of the Library already present on the user s computer system and b will operate properly with a modified version of the Library that is interface compatible with the Linked Version e Provide Installation Information but only if you would otherwise be required to provide such information under section 6 of the GNU GPL and only to the extent t
193. ng of internet traffic from GPRS e Log File setting this parameter enables textfile logging of OpenBTS activity Use rmconfig lt logging related parameter gt to disable the particular type of log again SIPAuthServe and SMQueue have their own log level settings which can be configured using the OpenRAN UI or by manually editing the corresponding sqlite3 configuration database Note Excessive logging can affect the operation of the BTS Appendix E Multi BTS Networks E 1 How Mobility WorkS a a asosa sa maea adada mo 118 E 1 1 How Mobility Works In GSM s ss s 622 8 2245 i RR ER Rew ee RS 118 E 1 2 How Mobility Works in SIP s gt o s asac e gaar anrd aee aea E aea 119 E 1 3 Combined GSM SIP Mobility in OpenBTS 00 120 E 2 Example of Mobility Configuration Simple Case o aa 120 E 3 Example of Mobility Configuration More Advanced Case 122 E 4 Handover 22 26 cc ee ura ERE AAA 123 EAL Handover Process aa Doms cs omei owe we Sh we OA A Bw eS ea a 124 E 4 2 PBX amp Switch Support aes mom o oan a ee a t i a aAa a O a a a at E a 126 E 4 3 Configuring Handover so rec po pat ea laa r 4 5 e UR e a G ie RES 126 E 5 Remote Logging 2202422440482 a ERR HE a e e a a 126 E 5 1 Configuring the Remote BTS Unit lt sa saose E 05 bop eR ewe ee ee eS 127 E 5 2 Configuring the Monitoring Station 2 2 a a 127 EDS Example vs d2m 2c44 4445 006 8 eg he CRD BE See who
194. ngle ARFCN BTS in a speech oriented application is e a Combination IV beacon on COTO carrying 4 SDCCHs and e six Combination l slots on COT1 COT7 carrying total of 7 TCH Fs This combination would typically support about about 15 authenticated registrations per minute about 40 text messages per minute and seven concurrent calls The number of subscribers that can actually be served with that capacity will be covered in the following sections A multi ARFCN speech oriented BTS with N ARFCNs would typically run e a Combination IV or Combination V beacon on COTO e N Combination VII slots carrying a total of 8V SDCCHs and e 7N Combination l slots carrying a total of 7N TCH Fs This configuration would support roughly 60N authentication registrations per minute 90N text messages per minute and 7N concurrent calls In either of these configuration examples an operator can trade call capacity for more SMS capacity by using more Combination VII slots and fewer Combination l Speech Call Capacity Telephone network capacity is measured in Erlangs where the Erlang number is the average number of sub scribers trying to use the network at any given moment the offered load during the busiest part of the day the busy hour To get the number of subscribers a BTS can support take its Erlang capacity and divide by the per subscriber offered load during the busy hour Offered loads run from 0 01 to 0 05 Erlang per subscriber depend
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196. ny kind of propagation that enables other parties to make or receive copies Mere interaction with a user through a computer network with no transfer of a copy is not conveying An interactive user interface displays Appropriate Legal Notices to the extent that it includes a convenient and prominently visible feature that 1 displays an appropriate copyright notice and 2 tells the user that there is no warranty for the work except to the extent that warranties are provided that licensees may convey the work under this License and how to view a copy of this License If the interface presents a list of user commands or options such as a menu a prominent item in the list meets this criterion 1 Source Code The source code for a work means the preferred form of the work for making modifications to it Object code means any non source form of a work A Standard Interface means an interface that either is an official standard defined by a recognized standards body or in the case of interfaces specified for a particular programming language one that is widely used among developers working in that language The System Libraries of an executable work include anything other than the work as a whole that a is included in the normal form of packaging a Major Component but which is not part of that Major Component and b serves only to enable use of the work with that Major Component or to implement a Standard Interface f
197. ollowed by the IMSI to un provisioned handsets that are denied registration Control LUR FailedRegistration ShortCode The return address for the failed registration mes sage If unset the message will not be sent Control LUR NormalRegistration Message The text message followed by the IMSI to be sent to provisioned handsets when they attach on Um By default no message is sent To have a message sent specify one To stop sending messages again execute unconfig Control LUR NormalRegistration Message Control LUR NormalRegistration ShortCode The return address for the normal registration mes sage If unset the message will not be sent Control LUR OpenRegistration This value is a regular expression Any handset with an IMSI match ing the regular expression is allowed to register even if it is not provisioned By default this feature is disabled To enable open registration specify a regular expression to match E g 001 which matches any IMSI starting with 001 the MCC for test networks To disable open registration again execute unconfig Control LUR OpenRegistration Control LUR OpenRegistration Message Send this text message followed by the IMSI to unpro visioned handsets when they attach on Um due to open registration Control LUR OpenRegistration Reject This value is a regular expression Any unprovisioned handset with an IMSI matching the regular expression is rejected for registration ev
198. on Reject and their open registration effects 7001 Match any IMSI starting with 001 the MCC for test networks 00105 Match any IMSI from the test network with MCC 001 and MNC 05 001050000000042 Match only IMSI 001050000000042 0 Match any IMSI containing a 0 1 Match any IMSI containing a 1 1024 Match any IMSI ending in 1024 The logic for processing registration requests is 1 Check the IMSI against the Subscriber Registry If it is not found proceed to Step 2 otherwise a Attempt to authenticate the handset b If the handset passes authentication accept it Done c If the handset fails authentication send it an authentication failure message which also implies a rejection Done 2 If Control LUR OpenRegistration is defined a If the IMSI does not match Control LUR OpenRegistration reject the handset with cause Control LUR UnprovisionedRejectCause Done b If the IMSI matches Control LUR OpenRegistration Reject reject the handset with cause Control LUR UnprovisionedRejectCause Done c Accept the handset Done Here are some open registration configuration examples 1 Accept only handsets with test SIMs MCC 001 e Control LUR OpenRegistration is 001 e Control LUR OpenRegistration Reject is an empty string 2 Accept only handsets with test SIMs having IMS Is that do not end in 0 e Control LUR OpenRegistration is 001
199. on a punctured rate 1 2 code but these intermediate rates are not currently supported by OpenBTS A 4 GENERAL PACKET RADIO SERVICE GPRS 81 TBF assignments that share the available channels which may impact the performance of individual MSs In the current implementation all MSs share channel bandwidth equally TCP Delays The underlying internet does not guarantee that data packets will be delivered Web browser sessions require guaranteed packet delivery so they usually use the TCP protocol which is a guaranteed delivery protocol that works by re transmitting packets that are lost The TCP IP algorithm assumes that packet loss is due to congestion on the internet and so it assumes that any packet that has not been delivered in a few seconds has been lost and retransmits it after a variable delay that is designed to reduce congestion globally on the internet Unfortunately this algorithm interacts badly with slow connections like GPRS There are multiple TCP algorithms in common use and TCP also deliberately introduces random numbers into the congestion avoidance algorithm so the exact delays incurred by TCP are difficult to characterize But typically when the amount of information to be transferred simultaneously for example when loading a single web page exceeds a threshhold that is approximately 25 KB per 10 KB sec of bandwidth then the information cannot be transferred before TCP starts retransmitting the packets This introduces two a
200. onfiguration some or all OpenBTS databases will have write ahead logging enabled 3 6 Folder Structure OpenBTS configuration databases are located in etc OpenBTS Asterisk configuration files are located separately according to Asterisk setup etc asterisk by default and the Subscriber Registry database is located at var lib asterisk sqlite3dir sqlite3 db OpenBTS run time data tables are located in var run OpenBTS Their locations are defined in the config uration table and can be changed to meet the requirements of your project 26 CHAPTER 3 GETTING TO KNOW YOUR OPENBTS SYSTEM 3 7 Logging The OpenBTS logging destination is controlled by the logging mechanism called rsyslogd which records all OpenBTS log messages to var log OpenBTS 1log It is configured with etc rsyslog d OpenBTS conf as follows local7 var log OpenBTS 1log The rsyslogd mechanism offers a range of powerful archival reporting and notification mechanisms including email notifications and routing of log messages to remote sites for network monitoring See the rsyslogd Unix manual pages for more information on these features OpenBTS logging level can be configured to provide the desired amount of detail including on per file basis See Appendix D for further details Chapter 4 OpenBTS Data Tables and Structures 4 1 Manipulating OpenBTS Databases o e eee eo 27 4 2 The Configuration Table
201. or cell update in seconds SIP DTMF RFC2967 Obsolete incorrect RFC number Use SIP DTMF RFC2976 SIP MaxForwards Maximum allowed number of referrals SIP Proxy Mode If set to direct then direct BTS to BTS calls are permitted without an intervening SIP switch for example no asterisk needed SIP RegistrationPeriod Registration period in minutes for MS SIP users Should be longer than GSM T3212 SIP Timer A SIP timer A the INVITE retry period RFC 3261 Section 17 1 1 2 in milliseconds SIP Timer B INVITE transaction timeout in milliseconds This value should usually match GSM Timer 1T3113 SIP Timer E Non INVITE initial request retransmit period in milliseconds SIP Timer F Non INVITE initial request timeout in milliseconds SIP Timer H ACK timeout period in milliseconds TRX MinimumRxRSSI Bursts received at the physical layer below this threshold are automatically ignored Values in dB Set at the factory Do not adjust without proper calibration TRX Port IP port of the transceiver application TRX RadioFrequency0ffset Fine tuning adjustment for the Transceiver master clock Roughly 170 Hz step Set at the factory Do not adjust without proper calibration 98 APPENDIX B CONFIGURATION PARAMETERS TRX Timeout Clock How long to wait during a read operation from the Transceiver before giving up TRX Timeout Start How long to wait during system startup before checking to s
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203. ork E 2 Example of Mobility Configuration Simple Case In this section we will consider the simplest OpenBTS mobility implementation where multiple BTS units share a common collection of central servers all running on the same physical machine An example of such a network is shown in Figure E 1 In this configuration there is a central server in a private IP network at 192 168 1 20 running central instances of Asterisk the subscriber registry and SMQueue There are three BTS units in the same subnet and the allowed ARFCNs are 40 42 and 44 For simplicity we show only the configuration parameters related to mobility network tg i public IP A do tg private IP Central network Server tg SIP switch EDO subscriber registry OpenBTS smqueue APs Figure E 1 A three BTS network with a common server Common configuration the same for all OpenBTS units E 2 EXAMPLE OF MOBILITY CONFIGURATION SIMPLE CASE 121 e SIP Proxy Registration 192 168 1 20 5064 the Subscriber Registry e SIP Proxy Speech and SIP Proxy Emergency 192 168 1 20 5060 Asterisk e SIP Proxy SMS 192 168 1 20 5063 SMQueue e SIP Local Port 5062 e GSM Radio ARFCNs 1 e GSM Identity MCC 001 e GSM Identity MNC 01 e GSM Identity NCC 0 e GSM CellSelection NCCsPermitted 1 matches GSM Identity NCC in bit 0 e GSM CellSelection CELL RESELECT HYSTERESIS 3 reselection threshold of 6 dB For unit A on ARFCN 40 at IP 192 168 1 30 e GSM Radio CO
204. ormat The reported values are C 6 CONFIG COMMANDS 105 e CN Channel number e TN Timeslot number e chan type The dedicated channel type or GPRS if reserved for Packet Services transaction id The key for the corresponding entry in the transaction table that is currently making use of this channel e LAPDm state The current acknowledged message state if any otherwise active or inactive recyc true if channel is recyclable i ei can be reused now e RSSI Uplink signal level dB above noise floor measured by BTS should be near config parameter GSM Radio RSSITarget e SNR Signal to Noise Ratio measured by the BTS higher is better less than 10 is likely unusable e BER Bit Error Rate before decoding measured by the BTS as a percentage e FER voice frame loss rate as a percentage measured by the BTS e TA Timing advance in symbol periods measured by the BTS e TXPWR Uplink transmit power dB reported by MS e TXTA Timing advance in symbol periods reported by MS e DNLEV Downlink signal level dB reported by MS e DNBER Downlink bit rrror rate percentage reported by MS e IMSI International Mobile Subscriber ld of the MS on this channel reported only if known e Frames number of bad stolen and total frames sent only for traffic channels Neighbor ARFCN and dBm One of the neighbors channel and downlink RSSI reported by the M
205. other ARFCNs except CO See Section A 4 3 The following parameters are defined as developer level parameters editable via devconfig command in the CLI only but are still worth a note here e GPRS RAC GPRS Routing Area Code advertised in the COTO beacon The combination of LAC GSM Identity LAC and RAC must be unique within the network If all cells have distinct LACs then this parameter does not matter 56 CHAPTER 9 GENERAL PACKET RADIO SERVICE GPRS GPRS RA_COLOUR GPRS Routing Area Color as advertised in the COTO beacon This parameter should be distinct from that advertised by any neighboring cells GPRS MS Power parameters See Section A 4 3 for details GPRS Codecs Downlink List of allowed GPRS downlink codecs expressed as a comma separated list of digits from 1 to 4 for CS 1 CS 4 For example 1 4 means GPRS may use codecs CS 1 and CS 4 The operator should normally not need to change this GPRS Codecs Uplink List of allowed GPRS uplink codecs expressed as a comma separated list of digits from 1 to 4 similar to GPRS Codecs Downlink The operator should normally not need to change this 9 1 3 Configuration Parameters for SGSN Functions To get information on the current SGSN status including IP addresses assigned to specific handsets use the CLI command sgsn list command Parameters associated with the SGSN functions of GPRS are prefixed with SGSN in the config
206. place that authentication is accomplished using the subscriber registry 3 The MS devices may activate deactivate PdpContexts on short timeframes meaning that they could potentially change IP addresses often This problem is mitigated by OpenBTS by making the IP addresses issued to the MS devices semi static meaning that the same MS will get the same IP address every time until the BTS is power cycled or the IP address pool is exhausted requiring re issue of previously issued IP addresses Appendix B Configuration Parameters B 1 OpenBTS Parameters 2 eee dd tardana a aka 85 B 1 1 Customer Site P ramet fS us goza rra ao aa e a ye ae 85 B 1 2 Customer Tuneable Parameters o 86 B 1 3 Developer Factory Parameters 2 20 93 B 2 Smqueue Parameters 0 ee a 98 B 2 1 Customer Site Parameters aooaa a a aa 98 B 2 2 Customer Tuneable Parameters a a 98 B 2 3 Developer Factory Parameters aoaaa 100 B 3 SiPAuthServe Parameters a 101 B 3 1 Customer Site Parameters 4 444 406 aaa a a ee ee eas 101 B 3 2 Customer Tuneable Parameters e a 101 B 3 3 Developer Factory Parameters 2 20 101 B 1 OpenBTS Parameters OpenBTS configuration parameters are stored in OpenBTS Configuration Table located at etc OpenBTS OpenBTS db See section 4 1 for details on the Configuration Table schema and access B 1 1 Customer Site Parameters These param
207. pleteness and to provide references to important parts of the GSM specifications to support more detailed study A 1 The OpenBTS GSM Air Interface This section describes the GSM air interface Um as implemented by OpenBTS Broadly speaking Um is organized into channels and layers as shown in Figure A 1 The rest of this section will explain this diagram 64 A 1 THE OPENBTS GSM AIR INTERFACE 65 SCH BCCH oo SDCCH SDCCH SDCCH TCH TCH TCH L3 L2 L1 Time Division Multiplexing GMSK Radiomodem Figure A 1 Layers and channels of the Um interface This figure shows the basic logical channel types in a subset of a typical configuration A 1 1 Um Layers The layers of GSM are initially defined in GSM 04 01 Section 7 and roughly follow the OSI model Um is defined in the lower three layers of the model Physical Layer L1 The Um physical layer is defined in the GSM 05 xx series of specifications with the introduction and overview in GSM 05 01 For most channels Um L1 transmits and receives 184 bit control frames or 260 bit vocoder frames over the radio interface in 148 bit bursts with one burst per timeslot There are three sublayers e Radiomodem This is the actual radio transceiver defined in largely in GSM 05 04 and 05 05 e Multiplexing and Timing GSM uses TDMA to subdivide each radio channel into as many as 16 traffic channels or as many as 64 control channels The multiplexing patterns are defined in GSM 05 02
208. plug in Public distribution available from pinesframework org pnotify The plug in is triple licensed under the GPL LGPL and MPL pySim Public distribution available from License is GNU General Public License v 2 SMQueue Source code available from Range Networks upon request License is GNU General Public License v 3 Ubuntu Linux distribution v 12 04 Public distribution available from ubuntu com The Ubuntu dis tribution includes a Linux kernel and a large number of utility applications distributed under a range of GPL licenses OpenBTS and its related applications use the following components the Linux kernel apache httpd cat erlang ifconfig iptables logrotate Ishw killall ntp openssl rm rsyslogd screen sh ssh wget This list may not be exhaustive BSD style License Compliance The following software components are used in OpenBTS under BSD Licenses A5 1 library Public distribution available from www scard org gsm Sparkline plug in Public distribution available from omnipotent net jquery sparkline The plug in is licensed under the 3 clause BSD License MIT License Compliance The following software components are used in OpenBTS under the MIT license jQuery library Public distribution available from jquery com jQuery UI library Public distribution available from jqueryui com 1 4 Source Code Availability The source code of Release 4 0 Public is available at github com RangeNetworks dev relea
209. pothetical commands show w and show c should show the appropriate parts of the General Public License Of course the commands you use may be called something other than show w and show c they could even be mouse clicks or menu items whatever suits your program You should also get your employer if you work as a programmer or your school if any to sign a copyright disclaimer for the program if necessary Here is a sample alter the names Yoyodyne Inc hereby disclaims all copyright interest in the program Gnomovision which makes passes at compilers written by James Hacker lt signature of Ty Coon gt 1 April 1989 Ty Coon President of Vice This General Public License does not permit incorporating your program into proprietary programs If your program is a subroutine library you may consider it more useful to permit linking proprietary applications with the library If this is what you want to do use the GNU Lesser General Public License instead of this License 152 APPENDIX G FOSS LICENSES G 4 GNU General Public License v 3 GNU GENERAL PUBLIC LICENSE Version 3 29 June 2007 Copyright C 2007 Free Software Foundation Inc lt http fsf org gt Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed Preamble The GNU General Public License is a free copyleft license for software and other kinds of works The licen
210. prepared so as to be conveniently linked with application programs which use some of those functions and data to form executables The Library below refers to any such software library or work which has been distributed under these terms A work based on the Library means either the Library or any derivative work under copyright law that is to say a work containing the Library or a portion of it either verbatim or with modifications and or translated straightforwardly into another language Hereinafter translation is included without limitation in the term modification G 5 GNU LESSER GENERAL PUBLIC LICENSE V 2 1 169 Source code for a work means the preferred form of the work for making modifications to it For a library complete source code means all the source code for all modules it contains plus any associated interface definition files plus the scripts used to control compilation and installation of the library Activities other than copying distribution and modification are not covered by this License they are outside its scope The act of running a program using the Library is not restricted and output from such a program is covered only if its contents constitute a work based on the Library independent of the use of the Library in a tool for writing it Whether that is true depends on what the Library does and what the program that uses the Library does 1 You may copy and distribute verbatim copies of the L
211. provides a searchable list of subscribers registered with the network including their names and phone numbers These parameters are tied to an IMSI and can be changed as needed You can also manually add or remove a subscriber Click on add subscriber and provide the necessary details then click on add to save them If you have a Range Networks SIM card writer part 48425 xxx series attached to your node you can use it to generate COMP128v1 SIMs with known IMSIs and known Ki supporting full RAND SRES authentication Click on write SIM and provide the necessary details then click on write The corersponding subscriber data will be added to the subscriber registry automatically 3 4 4 Monitoring the Node The Monitor panel provides the graphs representing the SDCCH and TCH channel loads AGCH and PCH queue sizes and the level of noise With the Monitor panel selected turn the toggle on the right to the Enabled position to initialize the monitors Each graph covers the period of 5 minutes Finally the Databases panel provides easy searchable access to the run time databases discussed in full detail in Chapter 4 3 5 Databases OpenBTS uses a set of sqlite3 database files to store its configuration parameters and run time data For more information on sqlite3 see the www sqlite org web site Chapter 4 discusses the data structures and their use in full detail Note Depending on your c
212. r ThresholdDelta This is the power level difference in dB between the serving cell and the neighbor cell at which handover is initiated In other words when a neighbor cell s RSSI level exceeds the serving cell s RSSI level as the handset by this much the serving BTS will initiate a handover to the neighbor e GSM Handover LocalRSSIMin This is the power level above which handover will not be attempted Regardless of the neighbor cell RSSI levels if the serving cells RSSI is above this level the BTS will not initiate the handover E 5 Remote Logging In multi BTS networks it is extremely useful to be able to selectively forward log events to a central monitoring station The rsyslog software used in most OpenBTS installations supports this function already it just needs E 5 REMOTE LOGGING 127 to be configured E 5 1 Configuring the Remote BTS Unit To send log events to a remote host via UDP add this line to etc rsyslog d OpenBTS conf local7 lt level gt lt host gt lt port gt To send to a remote host via TCP use local7 lt level gt lt host gt lt port gt For either protocol the port parameter is optional and defaults to the standard port of 514 In either case all log events at or numerically below the given logging level will be echoed to the given remote host over the specified protocol The original configuration line writing to var log OpenBTS log will still be in effect producing an additional
213. r minute under good conditions so a typical single ARFCN con figuration having 4 SDCCHs can process about 30 registrations per minute and still have half of its SDCCH capacity available for SMS Registration can be periodic driven by the GSM Timer T3212 parameter Sec tion 4 2 or it can be the result of mobility as phones move between cells in a multi BTS network Chapter E As an example if a network is configured with a T3212 of one hour and can process 30 authenticated registrations per minute then it can support 1 800 idle phones But that is just one configuration example There are many other possibilities add a Combination VII slot to process more registrations but at the expense of call capacity or extend or disable the periodic registration timer at the expense of presence information This simple analysis also ignores mobility assuming that subscribers are not moving much between cells so the real numbers will be lower but how much lower is very site specific For example if there is a major road passing through the service area the registration load might be much higher So the practical limit on the number of idle phones depends on the capacity and configuration of the cell site the degree of mobility and the time granularity of the presence information the operator wants but that limit is on the order of 1 000 phones per ARFCN at the low end in most realistic installations and can be made much higher if TCH F channels
214. r more information contact supportOrangenetworks com Free Support Free support is available through the OpenBTS public mailing list See the openbts org web site for more information Chapter 2 Introduction to OpenBTS Application Suite 2 1 Key Programs lt i4 242 c4c sra ara ARA 15 DMS ADEN BS des ae a a Bese dre a th ee pe the y 15 21 2 Wranseewer 4 4 20424 eo BH a Ge de Pewee ee RR ES ES 15 PWS SMOE O et aks de iaie 15 214 SIP route PBX o s desa pe ook a AE ds oe ee ely 15 2 15 SIPAUTAS ee is as o ka Shee a a A 16 2 2 Network Organization mis tir amp A ee oe Rae ee A AA 16 A complete OpenBTS installation comprises several distinct applications e OpenBTS The actual OpenBTS application containing most of the GSM stack above the radiomodem e Transceiver The software radiomodem and hardware control interface e SMQueue The RFC 3428 store and forward server for text messaging e Asterisk The VoIP PBX or softswitch e SIPAuthServe An application managing the database of subscriber information e Other Services Optional services supported through external servers interfaced to OpenBTS through various protocols In OpenBTS these services are NodeManager the JSON management API to allow third party applications to manage the essen tial OpenBTS suite components OpenBTS SMQueue and SIPAuthServe The OpenRANUI web interface provided with the Commercial release of OpenBTS uses NodeMa
215. ranted for the term of copyright on the Program and are irrevocable provided the stated conditions are met This License explicitly affirms your unlimited permission to run the unmodified Program The output from running a covered work is covered by this License only if the output given its content constitutes a covered work This License acknowledges your rights of fair use or other equivalent as provided by copyright law You may make run and propagate covered works that you do not convey without conditions so long as your license otherwise remains in force You may convey covered works to others for the sole purpose of having them make modifications exclusively for you or provide you with facilities for running those works provided that you comply with the terms of this License in conveying all material for which you do not control copyright Those thus making or running the covered works for you must do so exclusively on your behalf under your direction and control on terms that prohibit them from making any copies of your copyrighted material outside their relationship with you Conveying under any other circumstances is permitted solely under the conditions stated below Sublicensing is not allowed section 10 makes it unnecessary 3 Protecting Users Legal Rights From Anti Circumvention Law No covered work shall be deemed part of an effective technological measure under any applicable law fulfilling obligations under article
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217. re failures or documentation errors and will make reasonable efforts to correct these in future releases 1 3 2 Accuracy This manual is a description of the OpenBTS software not a specification In any discrepancy between the software and this manual the software source code is authoritative 1 3 3 Patent Laws The use of this software to provide GSM services may result in the use of patented technologies The user of this software is required to take whatever actions are necessary to avoid patent infringement 1 3 DISCLAIMERS 9 1 3 4 Trademarks OpenBTS is a registered trademark of Range Networks Inc Range a US corporation Range reserves the right to control the use of this trademark Do not use this trademark in commerce without permission and do not rebrand OpenBTS under a different trademark Asterisk is a trademark of Digium Inc 1 3 5 Telecom and Radio Spectrum Laws Users of this software are expected to comply with all applicable local national and international regulations 1 3 6 FOSS License Compliance OpenBTS Release 4 0 Commercial is distributed in binary form under a commercial license with copyrights assigned to Range Networks Inc protected under copyright law OpenBTS Release 4 0 Public is distributed in source code form under APGLv3 protected under copyright law This software is not public domain AGPLv3 is a commercial software license enforceable like any other This section l
218. reports are averaged To be considered for handover a neighbor must appear in 2 of the last GSM Neighbors Averaging measurement reports sent by the MS 96 APPENDIX B CONFIGURATION PARAMETERS GSM RRLP ACCURACY Requested accuracy of location request K in r 10 1 1 K 1 where r is the accuracy in meters See 3GPP 03 32 Sec 6 2 GSM RRLP ALMANAC ASSIST PRESENT Send almanac info to mobile GSM RRLP ALMANAC REFRESH TIME How often the almanac is refreshed in hours GSM RRLP ALMANAC URL URL of the almanac source GSM RRLP EPHEMERIS ASSIST COUNT Number of satellites to include in navigation model GSM RRLP EPHEMERIS REFRESH TIME How often the ephemeris is refreshed in hours GSM RRLP EPHEMERIS URL URL of ephemeris source GSM RRLP RESPONSETIME Mobile timeout OpenBTS timeout is 130 sec max response time 2 N in 2 N See 3GPP 04 31 Sec A 2 2 1 GSM RRLP SEED ALTITUDE Seed altitude in meters wrt geoidal surface GSM RRLP SEED LATITUDE Seed latitude in degrees 90 south pole 90 north pole GSM RRLP SEED LONGITUDE Seed longitude in degrees 180 west of greenwich 180 east GSM RRLP SERVER URL URL of RRLP server By default this feature is disabled To enable specify a server URL eg http localhost cgi rrlpserver cgi To disable again execute unconfig GSM RRLP SERVER URL GSM Radio NeedBSIC Whether the Radio type requir
219. risdictions in which the right to collect royalties through any statutory or compulsory licensing scheme can be waived the Licensor waives the exclusive right to collect such royalties for any exercise by You of the rights granted under this License and Voluntary License Schemes The Licensor waives the right to collect royalties whether individually or in the event that the Licensor is a member of a collecting society that administers voluntary licensing schemes via that society from any exercise by You of the rights granted under this License The above rights may be exercised in all media and formats whether now known or hereafter devised The above rights include the right to make such modifications as are technically necessary to exercise the rights in other media and formats Subject to Section 8 f all rights not expressly granted by Licensor are hereby reserved G 1 CREATIVE COMMONS LICENSE 137 4 Restrictions The license granted in Section 3 above is expressly made subject to and limited by the following restrictions You may Distribute or Publicly Perform the Work only under the terms of this License You must include a copy of or the Uniform Resource Identifier URI for this License with every copy of the Work You Distribute or Publicly Perform You may not offer or impose any terms on the Work that restrict the terms of this License or the ability of the recipient of the Work to exercise the rights granted to that recipient un
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222. ropriate parts of the General Public License Of course your program s commands might be different for a GUI interface you would use an about box You should also get your employer if you work as a programmer or school if any to sign a copyright disclaimer for the program if necessary For more information on this and how to apply and follow the GNU GPL see lt http www gnu org licenses gt The GNU General Public License does not permit incorporating your program 166 APPENDIX G FOSS LICENSES into proprietary programs If your program is a subroutine library you may consider it more useful to permit linking proprietary applications with the library If this is what you want to do use the GNU Lesser General Public License instead of this License But first please read lt http www gnu org philosophy why not 1gp1 html gt G 5 GNU Lesser General Public License v 2 1 GNU LESSER GENERAL PUBLIC LICENSE Version 2 1 February 1999 Copyright C 1991 1999 Free Software Foundation Inc 51 Franklin Street Fifth Floor Boston MA 02110 1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document but changing it is not allowed This is the first released version of the Lesser GPL It also counts as the successor of the GNU Library Public License version 2 hence the version number 2 1 Preamble The licenses for most software are designed to take away your freedom to share and
223. rt code is tied to an application which tells the sender how many messages are currently queued It is defined in the SC QuickChk Code parameter and is intended for administrative development use 7 3 2 Short Code Implementation The short code implementation in OpenBTS is primitive but functional Each short code handler is a C function coded directly into smqueue smcommands cpp The arguments to a short code handler are the source IMSI of the message the message text and a short_code_params data structure into which any reply message can be written The return value from a short code handler is a status code called short_code_action See smqueue smcommands cpp for examples Once a short code handler function is defined it must also be registered at a numeric address This happens in SMqueue init_smcommands also defined in smqueue smcommands cpp Chapter 8 Other GSM Services 8 1 Short Message Service Cell Broadcast SMSCB ooooo 53 8 2 Radio Resource Location Protocol RRLP o o o o 53 This chapter covers the configuration of 2G GSM services beyond speech and SMS text messaging 8 1 Short Message Service Cell Broadcast SMSCB The SMSCB data service is discussed in full detail in the Appendix section A 3 here we provide the configuration and OpenBTS implementation details The SMSCB service is disabled by default To enable it set the Control SMSCB Table
224. rt rsyslogd sudo service rsyslog restart Once this configuration is in place all OpenBTS related log events at or above the CRIT level will also be logged in var log OpenBTS log on the central server at 192 168 1 20 E 5 4 Email Notifications Rsyslogd can be configured to send notifications via email For maximum reliability this should be configured on each BTS unit To use this feature the Unix sendmail utility should be installed on each unit Sendmail can be installed or updated with the line sudo apt get install sendmail Once sendmail is installed rsyslog can be configured to send email notifications by adding lines like these to etc rsyslog conf Email notification ModLoad ommail ActionMailSMTPServer 127 0 0 1 ActionMailFrom openbts ActionMailTo support mynoc com template mailSubject alarm on hostname template mailBody msgh ActionMailSubject mailSubject make sure we receive a mail only once every 15 minutes ActionExecOnlyOnceEveryInterval 900 the if then mailBody must be on one line if syslogfacility text local7 and syslogseverity lt 1 then ommail mailBody E 5 REMOTE LOGGING 129 In the example above e Sendmail is running locally at 127 0 0 1 e The source address of the mail is openbts e The destination address of the mail is supportOmynoc com e The if then line at the end of the example will filter messages from fac
225. rtain designated libraries and is quite different from the ordinary General Public License We use this license for certain libraries in order to permit linking those libraries into non free programs When a program is linked with a library whether statically or using a shared library the combination of the two is legally speaking a combined work a derivative of the original library The ordinary General Public License therefore permits such linking only if the entire combination fits its criteria of freedom The Lesser General Public License permits more lax criteria for linking other code with the library We call this license the Lesser General Public License because it does Less to protect the user s freedom than the ordinary General Public License It also provides other free software developers Less of an advantage over competing non free programs These disadvantages are the reason we use the ordinary General Public License for many libraries However the Lesser license provides advantages in certain 168 APPENDIX G FOSS LICENSES special circumstances For example on rare occasions there may be a special need to encourage the widest possible use of a certain library so that it becomes a de facto standard To achieve this non free programs must be allowed to use the library A more frequent case is that a free library does the same job as widely used non free libraries In this case there is little to gain by limiting the
226. s carrying 20 50 bytes of user data each depending on the encoding codec type used and transferred at a rate of 50 frames per second per PhCH slot assigned to the MS The codec that OpenBTS uses in turn depends on the instantaneous link margin signal strength for each individual MS This means that the slowest GPRS connection single slot codec CS 1 is about 1000 bytes per second while the fastest downlink using the default multi slot configuration 2 up 3 down is about 50x50x3 7500 bytes per second Actual available payload rates are usually 10 30 lower due to TBF establishment overhead and TCP IP handshaking and header overhead Performance will be markedly lower as low as 1 2 of the maximum for applications that perform many small IP transfers since the ratio of overhead to payload is larger for smaller transfers CCCH Congestion If the MS and BTS have not communicated recently around 5 seconds OpenBTS must send TBF assignment messages to the MS using the same format as GSM immediate assignments which are carried on the AGCH Access Grant Channel and PCH Paging Channel subchannels of the CCCH The CCCH resource is shared with GSM phone call initiation sending of text messages periodic location and routing area upating messages and other services OpenBTS is currently capable of issuing up to a total of 12 CCCH messages sec of which 4 sec can be used to initiate uplink TBFs 4 sec can be used to initiate downlink TBFs
227. s allowing the BTS to adjust timing to 4 symbol e Timing Error This is a timing error measured by the BTS on the arriving signal Because timing advance is controlled to just 1 symbol errors in this range are normal Positive values mean that the signal is arriving later than ideal Negative values mean that the signal is arriving early The total roundtrip delay is timing advance timing error in symbol periods That sum multiplied by 535 is an estimate of the handset distance in meters 34 CHAPTER 5 OPENBTS AND THE TRANSCEIVER 5 2 Uplink Power and Timing Control 5 2 1 Uplink Power Control GSM uses a closed loop uplink power control described in GSM 05 08 Sections 4 1 4 2 and GSM 05 05 Section 4 1 1 The available maximum power levels of GSM MSs are given in Table 5 1 A multi band MS can and typically will have different power classes in each supported band The lowest available power output in any band is 5 dBm The power control range is set with the configuration parameters GSM MS Power Max and GSM MS Power Min both expressed in dBm These are normally set to 5 and 39 respectively These are global settings applied to all MSs equally For example the effect of setting GSM MS Power Max to something less than 39 in a GSM900 unit is to remove any range advantage that might be had by MSs power class 2 If an MS receives a power command that falls outside of its available power range that MS will set its output power
228. s or service marks or 160 APPENDIX G FOSS LICENSES f Requiring indemnification of licensors and authors of that material by anyone who conveys the material or modified versions of it with contractual assumptions of liability to the recipient for any liability that these contractual assumptions directly impose on those licensors and authors A11 other non permissive additional terms are considered further restrictions within the meaning of section 10 If the Program as you received it or any part of it contains a notice stating that it is governed by this License along with a term that is a further restriction you may remove that term If a license document contains a further restriction but permits relicensing or conveying under this License you may add to a covered work material governed by the terms of that license document provided that the further restriction does not survive such relicensing or conveying If you add terms to a covered work in accord with this section you must place in the relevant source files a statement of the additional terms that apply to those files or a notice indicating where to find the applicable terms Additional terms permissive or non permissive may be stated in the form of a separately written license or stated as exceptions the above requirements apply either way 8 Termination You may not propagate or modify a covered work except as expressly provided under this License Any at
229. s 1 See GSM 04 08 10 5 2 4 Table 10 5 23 and 04 08 9 1 8 Table 9 9 and the Control VEA parameter GSM Channels CisFirst Allocate C I slots first starting at COT1 Otherwise allocate C VII slots first GSM Channels NumC1s Number of Combination timeslots to configure The C I slot carries a single full rate TCH used for speech calling GSM Channels NumC7s Number of Combination VIl timeslots to configure The C VII slot carries 8 SDCCHs useful to handle high registration loads or SMS If COTO is C IV you must also have at least one C VII GSM Channels SDCCHReserve Number of SDCCHs to reserve for non LUR operations This can be used to force LUR transactions into a lower priority GSM Cipher CCHBER Probability of a bit getting toggled in a control channel burst for cracking pro tection GSM Cipher Encrypt Encrypt traffic between MS and OpenBTS GSM Cipher RandomNeighbor Probability of a random neighbor being added to SI5 for cracking pro tection GSM Cipher ScrambleFiller Scramble filler in layer 2 for cracking protection GSM Handover FailureHoldoff The number of seconds to wait before attempting another handover with a given neighbor BTS GSM Handover LocalRSSIMin Do not handover if downlink RXLEV reported by the MS is above this level in dBm regardless of power difference GSM Handover ThresholdDelta A neighbor downlink signal must be this much stronger in dB
230. s meaningful 170 APPENDIX G FOSS LICENSES For example a function in a library to compute square roots has a purpose that is entirely well defined independent of the application Therefore Subsection 2d requires that any application supplied function or table used by this function must be optional if the application does not supply it the square root function must still compute square roots These requirements apply to the modified work as a whole If identifiable sections of that work are not derived from the Library and can be reasonably considered independent and separate works in themselves then this License and its terms do not apply to those sections when you distribute them as separate works But when you distribute the same sections as part of a whole which is a work based on the Library the distribution of the whole must be on the terms of this License whose permissions for other licensees extend to the entire whole and thus to each and every part regardless of who wrote it Thus it is not the intent of this section to claim rights or contest your rights to work written entirely by you rather the intent is to exercise the right to control the distribution of derivative or collective works based on the Library In addition mere aggregation of another work not based on the Library with the Library or with a work based on the Library on a volume of a storage or distribution medium does not bring the other work under
231. s to a new cell Neighbor Lists Every BTS broadcasts a list of ARFCNs of neighboring cells called the neighbor list on the BCCH This list is also sent on the SACCH during transactions and calls The MS monitors these ARFCNs measuring their power levels and decoding their SCH bursts In idle mode the MS compares these power levels to the power level of its serving cell When the power level of the strongest neighbor exceeds that of the serving cell by a given threshold the MS will recamp from the current serving cell to the strong neighbor The power difference threshold at which this happens is called the cell reselection hysteresis a parameter broadcast on the BCCH If the LAC of the new cell is different from the previous cell the MS will also make a location updating request to ensure proper routing of inbound transactions BTS Configuration In the OpenBTS configuration the following parameters are relevant for mobility e GSM Radio CO amp GSM Radio ARFCNs e all GSM Identity parameters e all GSM CellSelection parameters See Section 4 2 for information about these parameters Many of these parameters have been assigned the default values that would work for most multi BTS applications however the following parameters must be provided by the operator e GSM Radio C0 amp GSM Radio ARFCNs although GSM Radio ARFCNs is usually dictated by the hardware e all GSM Identity parameters e GSM CellSelection NCCs
232. se conditions a The work must carry prominent notices stating that you modified it and giving a relevant date b The work must carry prominent notices stating that it is released under this License and any conditions added under section 7 This requirement modifies the requirement in section 4 to keep intact all notices c You must license the entire work as a whole under this License to anyone who comes into possession of a copy This License will therefore apply along with any applicable section 7 additional terms to the whole of the work and all its parts regardless of how they are packaged This License gives no permission to license the work in any other way but it does not invalidate such permission if you have separately received it d If the work has interactive user interfaces each must display Appropriate Legal Notices however if the Program has interactive interfaces that do not display Appropriate Legal Notices your work need not make them do so A compilation of a covered work with other separate and independent works which are not by their nature extensions of the covered work and which are not combined with it such as to form a larger program G 4 GNU GENERAL PUBLIC LICENSE V 3 157 in or on a volume of a storage or distribution medium is called an aggregate if the compilation and its resulting copyright are not used to limit the access or legal rights of the compilation s users beyond what the i
233. ses for most software and other practical works are designed to take away your freedom to share and change the works By contrast the GNU General Public License is intended to guarantee your freedom to share and change all versions of a program to make sure it remains free software for all its users We the Free Software Foundation use the GNU General Public License for most of our software it applies also to any other work released this way by its authors You can apply it to your programs too When we speak of free software we are referring to freedom not price Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software and charge for them if you wish that you receive source code or can get it if you want it that you can change the software or use pieces of it in new free programs and that you know you can do these things To protect your rights we need to prevent others from denying you these rights or asking you to surrender the rights Therefore you have certain responsibilities if you distribute copies of the software or if you modify it responsibilities to respect the freedom of others For example if you distribute copies of such a program whether gratis or for a fee you must pass on to the recipients the same freedoms that you received You must make sure that they too receive or can get the source code And you must show them these terms so they know their ri
234. ses tag v4 0 0 1 5 1 5 ABBREVIATIONS Abbreviations APDU application protocol data unit APN Access Point Name ARFCN absolute radio frequency channel number BTS base transceiver subsystem dB Decibels dBm Decibel milliwatts FEC forward error correction GPL General Public License GPRS General Packet Radio Service kHz kilohertz LGPL Lesser General Public License MOC mobile originated call MO SMS mobile originated SMS MTC mobile terminated call MT SMS mobile terminated SMS MS mobile station PDU protocol data unit RF radio frequency RPDU relay layer protocol data unit RRLP radio resource location protocol SIP Session Initiation Protocol SMS Short Message Service TDM time division multiplexing TPDU transfer layer protocol data unit USSD unstructured supplementary service data W Watts 11 12 CHAPTER 1 GENERAL INFORMATION 1 6 References 1 6 1 References to ETSI Documents References to the Phase 2 GSM specification series are given as GSM xx yy where xx yy is the specification number within the series References to the 3GPP specification series are similarly given as 3GPP xx yyy References to IETF specifications are given as RFC xxxx References to ITU T specifications are given as ITU T xx y 1 6 2 ETSI 3GPP This document references the following GSM and 3GPP specifications which ca
235. sk e GGSN DNS disabled When not specified explicitly DNS servers of the host system are used NAT configuration is stored in etc OpenBTS iptables rules file and loaded in etc network inferfaces at system boot The default NAT rules work with both static and dynamic IP addresses of the host system assuming that ethO interface is used for internet connectivity Should you be using a different interface you need to modify the NAT rules See Section A 4 2 for details See Section A 4 2 for discussion on security implications of using Linux NAT on a BTS unit and various ways of configuring it 9 1 2 Configuration Parameters for BSS Functions Parameters associated with the BSS functions layers 1 amp 2 of GPRS are prefixed with GPRS in the configuration table The configuration parameters of particular interest to an operator are e GPRS Enable Enable GPRS service 0 or 1 If enabled GPRS service is advertised in the COTO beacon and GPRS service may be started on demand See also GPRS Channels x e GPRS ChannelCodingControl RSSI If the signal strength is less than this amount in dB GPRS uses a lower speed codec CS 1 with less bandwidth but more robust encoding Note that dB numbers are negative e GPRS Channels Min CO Number of timeslots allocated for GPRS service from the CO first ARFCN See Section A 4 3 e GPRS Channels Min CN Total number of timeslots allocated for GPRS service from all
236. sted F 2 TESTING WITH OPEN REGISTRATION 133 Location Updating This test exercises the Um link between the BTS and handset This test must be conducted first to establish service on the handset for the other procedures 1 In OpenBTS set Control LUR OpenRegistration to to enable open registration Do not leave OpenBTS in this configuration for long periods since it could disrupt local cellular service This parameter is a regular expression used to match SIMs selectively and means accept any SIM 2 In OpenBTS define the Control LUR OpenRegistration Message to some non null string and set Con trol LUR OpenRegistration ShortCode to 101 3 Power up the handset within about 5 meters 15 feet of the BTS unit test antenna 4 The handset will attach to the BTS within a few seconds perform a successful location update and show service 5 The handset will receive a text message from 101 containing the open registration welcome message Autoprovisioning The autoprovisioning test verifies correct interaction between OpenBTS SMQueue and the Subscriber Registry 1 Perform the location updating procedure described in the previous section 2 Send a text message to 101 containing a 10 digit telephone number 3 Within a minute the handset should receive a text message verifying successful provisioning MTC and MOC with Newly Provisioned Handsets The MTC and MOC tests verify correct interaction betwee
237. system initialization and restart automatically should either one crash or exit 7 8 CHAPTER 1 GENERAL INFORMATION e Remote management interface OpenRANUI over http integrating subscriber provisioning SIM card creation configuration and monitoring tools for all major components of the application suite e No AGPLv3 license restrictions 1 1 Scope and Audience This document describes the organization and operation of the OpenBTS Release 4 0 series GSM access point software It is intended for use by software developers and network operators 1 2 License and Copyright Copyrights to this document are held by Range Networks Inc It is distributed under a Creative Commons Attribution ShareAlike 3 0 Unported License See the Appendix Creative Commons License for more infor mation 1 3 Disclaimers 1 3 1 Warranty The OpenBTS software and its associated documentation are provided with NO WARRANTY OF ANY KIND Although the information in this handbook has been carefully checked for accuracy and is believed to be correct and current no warranty either express or implied is made as to either its applicability to or its compatibility with specific requirements nor does Range Networks Inc assume any responsibility for correctness of this information nor for damages consequent to its use All design characteristics and specifications are subject to change without notice Range Networks Inc welcomes any reports of softwa
238. t Network short name displayed on some phones Optional but must be defined if you also want the network to send time of day string Range customer site these values are different for each BTS and should not be left default 0 0 9a zA Z value must be the same across all nodes The config command followed by a partial parameter name gives a list of all parameters with names con taining that partial name For example OpenBTS gt config Identity GSM Identity BSIC BCC 1 GSM Identity BSIC NCC 3 GSM Identity CI 10 GSM Identity LAC 1010 GSM Identity MCC 001 GSM Identity MNC 05 default default GSM Identity ShortName Range default OpenBTS gt To set a parameter to a certain value provide the parameter name followed by the new value to the config command like this OpenBTS gt config GSM Identity ShortName MyCellularNetwork GSM Identity ShortName changed from Range to MyCellularNetwork OpenBTS gt To revert a parameter to the default value use the rmconfig command like this OpenBTS gt rmconfig GSM Identity ShortName GSM Identity ShortName set back to its default value OpenBTS gt config GSM Identity ShortName 3 3 OPENBTS COMMAND LINE INTERFACE CLI 23 GSM Identity ShortName Range default description Network short name displayed on some phones Optional but must be define type string default value Range visibility level customer sit
239. t e From one of the handsets place a call to the number assigned to another handset e The call should ring at the second handset and connect normally when answered e When the call is terminated it should be a normal termination with no warnings e Try the test with each originating and terminating handset disconnect F 2 Testing with Open Registration The open registration feature Section 6 2 3 provides a mechanism for testing components of an OpenBTS installation in a standalone manner F 2 1 Interference Prevention Because of the potential for interference to existing networks this testing should be conducted only at low power levels and without mast mounted antennas The recommended procedure is to use a small omni antenna Range part 8101 000 or similar connected directly to the antenna connector for multiband units connect the antenna to the RX antenna connector For BTS units with output power greater than 1 Watt Range 5150 series xx5 and xx7 types a high power attenuator should be used Range part 48435 207 or equivalent between the BTS and the antenna F 2 2 Test Procedures Unlike the test SIM procedures of the previous section the open registration tests exercise the subscriber registry and the connections among the Subscriber Registry Asterisk SMQueue and OpenBTS All of these procedures are performed with open registration enabled using a handset with a SIM card that is novel to the basestation being te
240. t config GSM Identity MCC 901 GSM Identity MCC changed from 001 to 901 Not all configuration parameters can be accessed via the config command See devconfig and rawconfig commands for further details Also see the rmconfig command which resets parameters to their default val ues C 7 devconfig Command Certain parameters are not meant to be edited in the normal workflow but might require tweaking in the devel opment environment By default config hides these parameters from the user To review and manipulate them use the less restrictive devconfig command See Appendix section for information on specific configuration values and their effect of the system C 8 endcall Command Force the termination of a call or other transaction endcall lt transactionID gt C 9 FREQCORR COMMAND 107 C 9 freqcorr Command This command reads the radio frequency offset and allows to set a different offset The format is as follows OpenBTS gt freqcorr current freq offset is 128 C 10 gprs Command This command is used to invoke a number of subcommands the GPRS subsystem The syntax is gprs subcommand lt options gt C 10 1 gprs list Subcommand The list subcommand prints active objects of specified type gprs list ms tbf ch v x c lt id gt If ms tbf or ch is specified the listing is limited to that type of entit
241. t key kc varchar 33 default Kc the session encryption key not yet used prepaid int 1 default 0 not null 1 for pre paid subscribers not yet fully supported calllimit int 5 default 1 account_balance int 9 default O not null RRLPSupported int 1 default 1 not null hardware varchar 20 regTime integer default 0 not null a3_a8 varchar 45 default null For Asterisk the Subscriber Registry database forms part of the SIP registry and dialplan For other applications in the OpenBTS suite the registry fills the role normally filled by the HLR and VLR in a conventional GSM net 6 1 SUBSCRIBER REGISTRY 37 work Like an HLR the registry stores subscriber information and also provides A3 RAND SRES authentication Section A 1 3 for subscribers with known Ki Because Asterisk and SIPAuthServe access the sqlite3 database through a file interface they must be running on the same physical server The path to this database is stored in the SubscriberRegistry db parameter of the SIPAuthServe configuration The default location is var lib asterisk sqlite3dir sqlite3 db Asterisk expects to find the database file in this location so this value should not be changed 6 1 1 Configuring the Subscriber Registry The Subscriber Registry configuration parameters are stored in the database located at etc OpenBTS sipauthserve db They can be edited if needed using the OpenRANUI web interface by selecting the
242. tart of each source file to most effectively state the exclusion of warranty and each file should have at least the copyright line and a pointer to where the full notice is found lt one line to give the program s name and a brief idea of what it does gt Copyright C lt year gt lt name of author gt This program is free software you can redistribute it and or modify it under the terms of the GNU General Public License as published by the Free Software Foundation either version 3 of the License or at your option any later version This program is distributed in the hope that it will be useful but WITHOUT ANY WARRANTY without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE See the GNU General Public License for more details You should have received a copy of the GNU General Public License along with this program If not see lt http www gnu org licenses gt Also add information on how to contact you by electronic and paper mail If the program does terminal interaction make it output a short notice like this when it starts in an interactive mode lt program gt Copyright C lt year gt lt name of author gt This program comes with ABSOLUTELY NO WARRANTY for details type show w This is free software and you are welcome to redistribute it under certain conditions type show c for details The hypothetical commands show w and show c should show the app
243. te or to transfer 5 10 SMS per minute Fast Associated Control Channel FACCH The FACCH is always paired with a traffic channel The FACCH is a blank and burst channel that operates by stealing bursts from its associated traffic channel Bursts that carry FACCH data are distinguished from traffic bursts by stealing bits at each end of the midamble The FACCH is used for in call signaling including call disconnect handover and the later stages of call setup It has a payload data rate of 9 2 kbit s when paired with a full rate channel FACCH F and 4 6 kbit s when paired with a half rate channel FACCH H The FACCH uses the same interleaving and multiframe structure as its host TCH Slow Associated Control Channel SACCH Every SDCCH or FACCH also has an associated SACCH Its normal function is to carry system information messages 5 and 6 on the downlink carry receiver measurement reports on the uplink and to perform closed loop power and timing control Closed loop timing and power control are performed with a physical header at the start of each L1 frame This 16 bit physical header carries actual power and timing advance settings in the uplink and ordered power and timing values in the downlink The SACCH can also be used for in call delivery of SMS The SACCH has a payload data rate of 0 2 0 4 kbit s depending on the channel with which it is associated The SACCH uses 4 burst block interleaving and the same multiframe type as its host TCH or SDCCH
244. ted key value pairs C 3 calls Command List in progress Q 931 and SMS transactions from the transaction table Section 4 4 Displayed information includes 104 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE e transaction id The key for the corresponding entry in the transaction table that is currently making use of this channel e SIP call state e Q 931 GSM call state e time since last state change e subscriber IMSI e called or calling party number C 4 cellid Command Display or change cell identity parameters These parameters are e MCC Mobile Country Code 3 digits e MNC Mobile Network Code 2 or 3 digits e LAC Location Area Code 16 bits 1 65520 are valid values e Cl Cell Identity 16 bits 0 65535 are valid values With no arguments this command displays the current MCC MNC LAC and Cl values With arguments cellid lt MCC gt lt MNC gt lt LAC gt lt CI gt this command sets the parameters to the given values and updates the corresponding GSM Indentity config uration table parameters as described in Section 4 2 Using the command with arguments will also cause the TMSI Table to be cleared C 5 chans Command This command displays physical channel status from the channel table Section 4 5 for active dedicated chan nels The command accepts the following options e a report for all channels e longer listing e tab tab separated output f
245. tempt otherwise to propagate or modify it is void and will automatically terminate your rights under this License including any patent licenses granted under the third paragraph of section 11 However if you cease all violation of this License then your license from a particular copyright holder is reinstated a provisionally unless and until the copyright holder explicitly and finally terminates your license and b permanently if the copyright holder fails to notify you of the violation by some reasonable means prior to 60 days after the cessation Moreover your license from a particular copyright holder is reinstated permanently if the copyright holder notifies you of the violation by some reasonable means this is the first time you have received notice of violation of this License for any work from that copyright holder and you cure the violation prior to 30 days after your receipt of the notice Termination of your rights under this section does not terminate the G 4 GNU GENERAL PUBLIC LICENSE V 3 161 licenses of parties who have received copies or rights from you under this License If your rights have been terminated and not permanently reinstated you do not qualify to receive new licenses for the same material under section 10 9 Acceptance Not Required for Having Copies You are not required to accept this License in order to receive or run a copy of the Program Ancillary propagation of a covered work occurrin
246. ternet Protocol services These registrations last for a programmable period typically about an hour after which they must be renewed The GSM registration is periodically renewed using a Location Area Update command and the GPRS registration is renewed using a Routing Area Update command If GPRS is enabled then almost any MS in range of the BTS will attempt to register whether they intend to use GPRS packet services or not For this reason there will be continual GPRS activity even if there is no packet flow You can view a list of registered devices via the OpenBTS CLI command sgsn list 80APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS Temporary Block Flow A GPRS channel assignment is called a TBF Temporary Block Flow In a TBF an MS is granted the use of one or more PhCH physical channels to transfer IP data Each PhCH occupies one timeslot on one ARFCN Adjacent PhCHs can be ganged to provide multi slot transfer capability OpenBTS creates a TBF when IP packets need to be transferred between the network and the MS The TBF remains open as long as there are IP packets to be transferred When there are no more IP packets being transmitted and the persistence delay has expired the TBF is released Another TBF will be established for the next transfer when the next IP packet arrives Performance Over each PhCH slot in a TBF IP packets are segmented in layer 2 into RLC frame
247. than this downlink signal for handover to occur GSM MS Power Damping Damping value for MS power control loop in percent The ordered MS power is based on RSSI Received Signal Strength Indication A value of 100 here ignores RSSI entirely a value of 0 causes the MS power to change instantaneously based on RSSI which is inadvisable because it sets up power oscillations The ordered MS power is then clamped between GSM MS Power Max and GSM MS Power Min GSM MS Power Max Maximum commanded MS power level in dBm GSM MS Power Min Minimum commanded MS power level in dBm GSM MS TA Damping Damping value for timing advance control loop GSM MS TA Max Maximum allowed timing advance in symbol periods One symbol period of round trip delay is about 0 55 km of distance Ignore RACH bursts with delays greater than this Can be used to limit service range Valid range is 1 62 B 1 OPENBTS PARAMETERS 91 GSM MaxSpeechLatency Maximum allowed speech buffering latency in 20 millisecond frames If the jitter is larger than this delay frames will be lost GSM Neighbors A list of IP addresses of neighbor BTSs available for handover By default handover is disabled To enable specify a space separated list of a maximum of 31 OpenBTS IP addresses in IP dotted notation optionally followed by a colon and the port number E g 1 2 3 4 5 6 7 8 16001 To disable again execute unconfig GSM Neighbors GSM Neighbors NumToSe
248. that you provide a warranty and that users may redistribute the program under these conditions and telling the user how to view a copy of this General Public License d You may charge a fee for the physical act of transferring a copy and you may at your option offer warranty protection in exchange for a fee Mere aggregation of another independent work with the Program or its derivative on a volume of a storage or distribution medium does not bring the other work under the scope of these terms 3 You may copy and distribute the Program or a portion or derivative of it under Paragraph 2 in object code or executable form under the terms of Paragraphs 1 and 2 above provided that you also do one of the following a accompany it with the complete corresponding machine readable source code which must be distributed under the terms of Paragraphs 1 and 2 above or b accompany it with a written offer valid for at least three years to give any third party free except for a nominal charge for the cost of distribution a complete machine readable copy of the corresponding source code to be distributed under the terms of Paragraphs 1 and 2 above or 142 APPENDIX G FOSS LICENSES c accompany it with the information you received as to where the corresponding source code may be obtained This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form alone
249. the procedure looks like any other GSM handover On the SIP 124 APPENDIX E MULTI BTS NETWORKS network interface the handover operation looks as if a SIP endpoint changed its IP address in mid call The full transaction ladder is shown in Figure E 3 including RPP messaging OpenBTS currently supports handovers of telephone calls but does yet not attempt handover during other circuit switched operations SMS USSD etc OpenBTS does support handover of emergency SOS calls if the serving switch or PBX is compatible with the procedure but OpenBTS does not update location information after the call is initiated remote MS BS1 BS2 party Neighbor Discovery Neighbor List Measurement Report REQ HANDOVER RSP HANDOVER Handover Command Handover Access Physical Information INVITE OK Handover Complete lt ACK IND HANDOVER ACK HANDOVER Figure E 3 GSM RPP and SIP signaling for OpenBTS handover In this example a call that originated on BTS1 is handed over to BTS2 The call is between the MS and the remote party Signaling between BTS units and MS is GSM Signaling between BTS units and the remote party is SIP Signaling between BTS1 and BTS2 is RPP E 4 1 Handover Process Handover is a complex process that affects every aspect and element of the OpenBTS software E 4 HANDOVER 125 Neighbor Information Exchange BTS units exchange configuration information directly using RPP On each BTS unit the GSM Neighbors configur
250. the standard authentication but the behavior of the registry is different and A3 is not actually run This authentication is weaker than full authentication but can but used when Ki is not known On the first encounter with an MS the registry generates a RAND value sends it to the MS and saves both the RAND and resulting SRES in the database The MS receives a successful authentication response for any correctly formatted SRES 38 CHAPTER 6 SIPAUTHSERVE SUBSCRIBER REGISTRY AND ASTERISK On subsequent authentications the registry sends the RAND value cached in the database and checks to see if the returned SRES matches the cached value SIPAuthServe automatically selects the authentication type based on the availability of Ki If Ki is known it uses full authentication Otherwise it uses cached authentication The type of registration actually used can be determined by looking into the sip_buddies database table to see if a Ki is present Note The GSM challenge response RAND SRES procedure is described in Section A 1 3 6 1 4 Configuring Authentication OpenBTS performs a SIP challenge response authentication with SIPAuthServe which updates the sip_buddies table Asterisk picks up the registration IP address as needed through an ODBC interface to the sip_buddies table This is a typical configuration for a public network with the real time Asterisk configuration The OpenBTS parameter setting this configuration
251. the terms of this License c If the modified program normally reads commands interactively when run you must cause it when started running for such interactive use in the most ordinary way to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty or else saying that you provide a Warranty and that users may redistribute the program under these conditions and telling the user how to view a copy of this License Exception if the Program itself is interactive but does not normally print such an announcement your work based on the Program is not required to print an announcement These requirements apply to the modified work as a whole If identifiable sections of that work are not derived from the Program and can be reasonably considered independent and separate works in themselves then this License and its terms do not apply to those sections when you distribute them as separate works But when you distribute the same sections as part of a whole which is a work based on the Program the distribution of the whole must be on the terms of this License whose permissions for other licensees extend to the entire whole and thus to each and every part regardless of who wrote it Thus it is not the intent of this section to claim rights or contest your rights to work written entirely by you rather the intent is to exercise the right to control the distribution of derivative or
252. tion and presents its IMSI or TMSI to the BSS TOAPPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS 2 If the MS provides a TMSI BSS resolves the TMSI to an IMSI either through a registry or through an L3 MM Identity Request message 3 The BSS sends the IMSI to the HLR AuC 4 The AuC generates a 128 bit random value RAND and sends it to the BSS which then sends it to the MS in the MM Authentication Request message 5 The MS forms a 32 bit hash value called SRES by encrypting RAND with an algorithm called A3 using Ki as a key SRES A3 RAND Ki The HLR AuC performs an identical SRES calculation 6 The MS sends back its SRES value in the RR Authentication Response message 7 The BSS relays the SRES IMSI and RAND back to the HLR AuC 8 The HLR AuC compares its calculated SRES value to the value returned by the MS If they match the MS is authenticated 9 Both the MS and the HLR AuC also compute a 64 bit ciphering key Kc from RAND and Ki using the A8 algorithm Kc A8 RAND ki 10 The HLR AuC reports Kc or a failure message to the BSS 11 The BSS saves Kc for ciphering and reports success or failure to the MS The OpenBTS version of this transaction is the same except that OpenBTS replaces the BSS and the subscriber registry replaces the HLR AuC The GSM specifications define the characteristics of A3 and A8 but not the algorithms themselves The specific A3 and A8 algorithms are s
253. to the closest level available maximum or minimum So there is no risk in setting these bounds wider than what the MS can actually support It may be desirable though in some installations to limit MS power to prevent interference to other cell sites in the area Table 5 1 Maximum output power levels for GSM MSs From GSM 05 05 Section 4 1 1 Power GSM850 GSM900 DCS1800 PCS1900 Class Max Ouput Max Output Max Output 1 N A 1 W 30 dBm 1 W 30 dBm 2 8 W 39 dBm 0 25 W 24 dBm 0 25 W 30 dBm 3 5 W 33 dBm 4 W 36 dBm 2 W 33 dBm 4 2 W 33 dBm N A N A 5 0 8 W 29 dBm N A N A 5 2 2 Uplink Timing Control GSM uses closed loop timing advance control described in GSM 05 10 Section 6 The configuration parameter GSM MS TA Max sets a limit on MS timing advance and can be used to deliberately limit the range of service The value is expressed in symbol periods of round trip delay at about 550 meters per step The normal value of this parameter is 63 which is also the maximum allowed value and corresponds to a maximum range of 35 km Chapter 6 SIPAuthServe Subscriber Registry and Asterisk 6 1 6 2 6 3 6 4 6 5 6 6 Subscriber Registry o e e ea ee 36 6 1 1 Configuring the Subscriber Registry a o o 37 6 1 2 Accessing the Subscriber Registry Commercial Release Only 37 6 1 3 SlPAuthServe Authenticatio
254. to reduce the total number of ARFCNs being powered at any given moment Since there will always be GPRS registration activity when GPRS is enabled the operator should always allocate some channels on ARFCN CO For best GPRS performance the number of channels allocated per ARFCN should be a multiple of the maximum multi slot allocation For example if GPRS Multislot Max Downlink is set at the default value of 3 then the optimal values for GPRS Channels Min CO are 3 or 6 Alternatively for a multi ARFCN BTS that is used primarily for voice calls and rarely for GPRS the operator could allocate just 1 GPRS channel on ARFCN CO to handle GPRS registration activity and still get multi slot GPRS capability by allocating more GPRS channels e g 3 on the other ARFCNs Multislot Allocation GPRS can group timeslots together to provide greater transfer bandwidth a feature called multi slotting The GPRS Multislot Max Uplink and GPRS Multislot Max Downlink pa rameters control the maximum number of slots that OpenBTS will provide to an MS device in the uplink and downlink directions respectively The multi slot configuration assigned to each MS is also limited by the This feature is available in release 3 1 and higher 82 APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS number of adjacent GPRS channels timeslots available for GPRS sevice when the TBF is created and also by the
255. ucing the executable from it However as a special exception the materials to be distributed need not include anything that is normally distributed in either source or binary form with the major components compiler kernel and so on of the operating system on which the executable runs unless that component itself accompanies the executable G 5 GNU LESSER GENERAL PUBLIC LICENSE V 2 1 173 It may happen that this requirement contradicts the license restrictions of other proprietary libraries that do not normally accompany the operating system Such a contradiction means you cannot use both them and the Library together in an executable that you distribute 7 You may place library facilities that are a work based on the Library side by side in a single library together with other library facilities not covered by this License and distribute such a combined library provided that the separate distribution of the work based on the Library and of the other library facilities is otherwise permitted and provided that you do these two things a Accompany the combined library with a copy of the same work based on the Library uncombined with any other library facilities This must be distributed under the terms of the Sections above b Give prominent notice with the combined library of the fact that part of it is a work based on the Library and explaining where to find the accompanying uncombined form of the same work 8 You may not
256. uration table These configuration parameters are unlikely to require changes and are only available using the devconfig command in the CLI 9 1 4 Configuration Parameters for GGSN Functions Parameters associated with the GGSN functions of GPRS are prefixed with GGSN in the configuration table Some of them have already been described above The configuration parameters of interest to an operator are GGSN Firewall Enable O no0 firewall 1 block MS attempted access to OpenBTS or other MS 2 block all private IP addresses See Section A 4 2 GGSN IP ReuseTimeout How long IP addresses are reserved after a session ends GGSN IP TossDuplicatePackets Any non zero integer causes duplicate TCP IP packets to be tossed away to prevent unnecessary traffic on the radio GGSN Logfile Name If specified internet traffic is logged to this file GGSN MS IP Base Base IP address assigned to MS GGSN MS IP MaxCount Number of IP addresses to use for MS GGSN MS IP Route The route address in the form xxx xxx xxx xxx yy must encompass all MS IP addresses If not specified OpenBTS manufactures this value from the GGSN MS IP Base assuming a 24 bit mask In addition there is a parameter GGSN ShellScript that enables a shell script that would run each time a new MS device activates GPRS services or creates an IP connection See Section A 4 3 for details 9 2 CONFIGURATION OF HANDSETS FOR OPENBTS GPRS 57 9 2
257. urce and binary forms with or without modification are permitted provided that the following conditions are met Redistributions of source code must retain the above copyright notice this list of conditions and the following disclaimer Redistributions in binary form must reproduce the above copyright notice this list of conditions and the following disclaimer in the documentation and or other materials provided with the distribution Neither the name of Splunk Inc nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS AS 15 AND ANY EXPRESS OR IMPLIED WARRANTIES INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT INDIRECT INCIDENTAL 180 APPENDIX G FOSS LICENSES SPECIAL EXEMPLARY OR CONSEQUENTIAL DAMAGES INCLUDING BUT NOT LIMITED TO PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES LOSS OF USE DATA OR PROFITS OR BUSINESS INTERRUPTION HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY WHETHER IN CONTRACT STRICT LIABILITY OR TORT INCLUDING NEGLIGENCE OR OTHERWISE ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE List of Figures 2 1 2 2 0 1 6 2 6 3 6 4 6
258. urce conveyed under this section must be accompanied by the Installation Information But this requirement does not apply if neither you nor any third party retains the ability to install modified object code on the User Product for example the work has been installed in ROM The requirement to provide Installation Information does not include a requirement to continue to provide support service warranty or updates for a work that has been modified or installed by the recipient or for the User Product in which it has been modified or installed Access to a network may be denied when the modification itself materially and G 4 GNU GENERAL PUBLIC LICENSE V 3 159 adversely affects the operation of the network or violates the rules and protocols for communication across the network Corresponding Source conveyed and Installation Information provided in accord with this section must be in a format that is publicly documented and with an implementation available to the public in source code form and must require no special password or key for unpacking reading or copying 7 Additional Terms Additional permissions are terms that supplement the terms of this License by making exceptions from one or more of its conditions Additional permissions that are applicable to the entire Program shall be treated as though they were included in this License to the extent that they are valid under applicable law If additional permissions app
259. vice e To and From e AgeSec transaction age in seconds e Start Time and End Time e Message Issued with the optional purge parameter the command purges the transaction records table C 31 trxfactory Command This command displays information stored in the radio at the factory only compatible with Range Networks hardware e SDR Serial Number e RF Serial Number e GSM Radio Band e TRX RadioFrequencyOffset e GSM Radio RxGain e TRX TxAttenOffset Note This command does not work in version 4 0 0 It is a known issue C 32 txatten Command When issued without parameters this command prints the transmitter attenuation in dB When issued with a parameter it sets the attenuation to the corresponding value For example C 33 UNCONFIG COMMAND 115 OpenBTS gt txatten current TX attenuation is O dB OpenBTS gt txatten 20 current TX attenuation is O dB new TX attenuation is 20 dB OpenBTS gt txatten current TX attenuation is 20 dB C 33 unconfig Command The unconfig command sets the value associated with the given key to an empty string in the configuration table effectively disabling it This command does not have effect on configuration parameters for which empty string is not a valid value unconfig lt key gt Example OpenBTS gt config Control LUR OpenRegistration 001 Control LUR OpenRegistration is already set to 001 nothing ch
260. whether gratis or for a fee you must give the recipients all the rights that you have You must make sure that they too receive or can get the source code And you must tell them their rights We protect your rights with two steps 1 copyright the software and 2 offer you this license which gives you legal permission to copy distribute and or modify the software Also for each author s protection and ours we want to make certain that everyone understands that there is no warranty for this free software If the software is modified by someone else and passed on we want its recipients to know that what they have is not the original so that any problems introduced by others will not reflect on the original authors reputations The precise terms and conditions for copying distribution and modification follow GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING DISTRIBUTION AND MODIFICATION O This License Agreement applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License The Program below refers to any such program or work and a work based on the Program means either the Program or any work containing the Program or a portion of it either verbatim or with modifications Each licensee is addressed as you 1 You may copy and distribute verbatim copies of the Program s source code as you receive it
261. wser sessions use many short individual transactions and can also recover from lost packets so this typical use scenario is less likely to be disrupted than a longer continuous transaction for example a file transfer or listening to music e Static IP addresses are not supported so all IP transactions must be initiated by the handset Alternate named IP portals are not supported which means all IP sessions simply go to the global internet rather than a specified server The APN Access Point Name if any is ignored e Connection to a customer specified SGSN or GGSN is not supported The SGSN and GGSN are internal to OpenBTS e There is no support for dual transfer mode which means no simultaneous voice call and IP session on a single handset 78 APPENDIX A OPENBTS IMPLEMENTATION OF GSM amp 3GPP SPECIFICATIONS AND IETF STANDARDS e The supported channel coding options are codecs CS 1 and CS 4 the slowest and the fastest e Total system performance may be limited by the available bandwidth of the CCCH Common Control Channel which may restrict the number of simultaneously active MSs This restriction has been greatly alleviated in release C3 1 and is reduced even further when the TBF persistence feature configuration parameter GPRS Uplink Persist is enabled however if a multi ARFCN BTS has a large number of channels dedicated to GPRS it may still be possible to encounter this limitation See Section A 4 3 for more details A
262. y If the optional lt id gt is specified it is the numeric ordinal identifier for an MS or TBF This is the same id that is part of the name of the MS or TBF For example to list just MS 1 the id is 1 The options for gprs list are v Verbose listing c include MS capabilities in the listing x list expired rather than active entities When invoked without options gprs list prints a short listing of the MS TBF and Channels in use by GPRS OpenBTS gt gprs list PDCH ARFCN 51 TN 1 FER 0 PDCH ARFCN 51 TN 2 FER 0 108 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE C 10 2 Other gprs Subcommands gprs console 0 1 Send messages to console as well as the Log File default 1 for debugging gprs debug level Set debug level 0 turns debugging off gprs free ms tbf ch lt id gt Free the corresponding entity gprs freex Free expired ms and tbf structs gprs help Print the complete list of commands available from the GPRS subsystem gprs mem Memory leak detector print numbers of structs in use gprs set name val Print and optionally set a variable see source for names gprs start step Start GPRS optionally in single step mode gprs stat Print GPRS statistics including total number of channels MS and TBF allocated gprs step Single step the MAC service loop requires start step gprs stop c Stop GPRS thread and release channels with optional c gprs rach Simulate a RACH wh
263. y use statistics C 15 neighbors Command This command displays the current neighbor table as generated through automatic neighbor information ex change Each line contains e the neighbor s IP address e the neighbor s CO ARFCN e the neighbor s BSIC C 16 noise Command The noise command reports receive noise level in RSSI dB as follows OpenBTS gt noise noise RSSI is 67 dB wrt full scale MS RSSI target is 50 dB wrt full scale INFO the current noise level is acceptable C 17 notices Command Print the copyright and legal notices associated with your installation of OpenBTS C 18 page Command Print the paging table 110 APPENDIX C THE COMMAND LINE INTERFACE CLI REFERENCE C 19 power Command Inspect or change the downlink power parameters described in Section 5 1 With no arguments this command displays the current power setting and bounds With arguments this command changes the power control bounds power lt minAtten gt lt maxAtten gt For example OpenBTS gt power 10 20 current downlink power O dB wrt full scale current attenuation bounds O to 10 dB new attenuation bounds 10 to 20 dB C 20 rawconfig Command The rawconfig command behaves much like config but with two additional features It can be used to define and manipulate custom key value pairs in the configuration table It also ignores any input validation allowing developers to enter exp

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