92313-vG System Description
Contents
1. IP Backbone LAN VoWiFi Handset Figure 9 A very large system more than 1000 VoWiFi Handsets or many shared phones 7 September 2011 Ver G 19 System Description Ascom VoWiFi System TD 92313EN 4 1 Supported Standards 4 1 1 VoWiFi Handset e EEE 802 11a b g n MCS 0 7 20 MHz 800ns GI e WEP WPA for security 802 11i WPA2 e WMM based on 802 11e e EEE 802 11d specification for operation in additional regulatory domains e WMM power save e CCX version 4 for Application Specific Device ASD e TSPEC based CAC e Pre authentication Proactive Key Caching Opportunistic key caching e PMKSA caching e CCKM e 802 11h DFS and TPC Encryption methods 64 128 bits WEP e TKIP e AES CCMP Authentication methods e 802 1X Original 802 11 open shared key authentication e WPA PSK e WPA2 PSK e LEAP e PEAP MSCHAPv2 e EAP TLS e EAP FAST e Authentication certificate For use in Cisco WLAN infrastructure CCKM is supported to speed up the encryption key exchange when roaming in a multi cell environment 4 2 System Functions The Ascom VoWiFi system is designed to enable wireless voice traffic messaging and alarm handling within an enterprise LAN For details see Function Description Ascom VoWiFi System TD 92314EN 1 The VoWiFi Handset requires the APs to support WMM for voice power save mode 7 September 2011 Ver G 20 System Descr2. Integrated Wireless Messaging and Services IMS3 or Unite Connectivity Manager Unite CM optional e VoIP Gateway Gatekeeper optional e SIP Proxy Server in the IP PBX optional e RADIUS Server optional In a small VoWiFi system with few VoWiFi Handsets the IMS3 Unite CM is optional The system can be managed with the PDM only but without an IMS3 Unite CM no messaging or alarm handling is possible and it will be a voice system only PDM IMS3 Unite CM e 7M N eee ceci IP Backbone LAN 4 q i VoWiFi Handset Figure 7 A small basic system IMS3 Unite CM is optional 7 September 2011 Ver G 18 System Description Ascom VoWiFi System TD 92313EN In a large system it is strongly recommended to use an IMS3 Unite CM and when using shared phones functionality it is required The IMS3 Unite CM is also required for messaging and alarm functions An Enhanced System Service ESS or a Unite CM is needed if individual passwords for shared phones are used PDM IMS3 ESS Unite CM User server Gn EE I IP Backbone LAN B ma A q f Figure 8 Shared phones require an IMS3 Unite CM In a very large system with more than 1000 VoWiFi Handsets or many shared phones that will log in at the same time additional IMS3s Unite CMs are needed IMS3 IMS3 Unite CM Unite CM
3. are guaranteed in advance Quadrature Phase Shift Keying Remote Authentication Dial In User Service a standard protocol for authentication servers Radio Frequency The process of moving a VoWiFi Handset from one AP to another when moving within the network Resource Reservation Protocol a QoS signalling protocol that nails down a channel through an IP network based on the session ID Real Time Control Protocol Real Time Protocol Real Time Streaming Protocol Session Announcement Protocol Session Description Protocol Session Initiation Protocol Small Office Home Office Time Division Multiple Access Transmit Power Control Traffic Specification Unlicensed National Information Infrastructure Ascom messaging platform A generic term for a messaging system that unites different systems for example System 900 System 9d and VoWiFi Unite Connectivity Manager Unite module that enables messaging and alarm handling in a WLAN system It also includes the Device Manager Voice over Internet Protocol the technology used to transmit voice conversations over IP Voice over Wireless Fidelity a wireless version of VoIP and refers to IEEE 802 11a 802 11b 802 11g or 802 11n network Wired Equivalent Privacy encryption keys the original security standard used in wireless networks to encrypt the wireless network traffic WiFi is a term developed by the Wi Fi Alliance to describe wireless local area network WLAN
4. available within a limited distance from an AP More resilient coding schemes are needed to decode signals with lower strength at the expense of data rate Also note that this is the maximum data rate which means that the maximum throughput is more likely to be half of that because of data headers etc As a client moves away from the AP data rate is reduced and consequently the throughput The average throughput is as a rule of thumb half of the data rate Therefore it is important that APs are not placed too far apart 2 2 2 802 11a RF Modulation Standard WLAN products based on the 802 11a standard operate in the 5 GHz frequency range This is an unlicensed frequency band called the Unlicensed National Information Infrastructure UNII band It is divided into the UNII 1 band 5 15 5 25 GHz the UNII 2 band 5 25 5 35 GHz the UNII 2 Extended band 5 47 5 710 GHz and the UNII 3 band 5 725 5 825 GHz depending on country regulations The UNII band is divided into 23 non overlapping channels depending on country regulations with a bandwidth of 20 MHz The centre frequencies are 20 MHz apart Originally the UNII 1 band was intended for indoor operation the UNII 3 band for outdoor operation and the UNII 2 and UNII 2 Extended band for both indoor and outdoor operation This distinction has been removed for FCC For ETSI the UNII 1 and UNII 2 bands are still intended for indoor operation and the UNII 2 Extended band for both indoo
5. comparing the ESSID the AP verifies that the VoWiFi Handset is allowed to associate with the AP and sends an acknowledgement Communication between the IP VoWiFi Handset and the AP is hereby established 4 3 3 Authentication Authentication is the process of verifying the credentials of a mobile device trying to access the network In a secure WLAN system additonal user authentication can be handled by a RADIUS server When the association process between the VoWiFi Handset and the AP is finished the VoWiFi Handset sends an authentication request The request is forwarded by the AP to the RADIUS server where parameters such as User Name and password are verified before network communication is allowed Once authenticated the information is stored in the Controller in a Controller based solution to shorten the process 7 September 2011 Ver G 21 System Description Ascom VoWiFi System TD 92313EN Note The authentication method is dependent on the security level set for the system The VoWiFi Handsets can be used in systems with no security as well as in systems with WPA PSK security RADIUS Server IP Backbone LAN E gt MEN VoWiFi Handset Figure 10 Association and Authentication 4 4 Network Parameter Download Network parameters such as ESSID must be defined in the VoWiFi Handset to enable network access Parameters are loaded to the VoWiFi Handset from the PDM For the Ascom VoWiFi Handset it is also
6. connected to the Controller and are basically just a radio and an antenna The Controller handles most of the MAC layer all by itself The use of controller based APs enhances operation of the VoWiFi system makes centralized administration over the WLAN possible and makes it easy to expand the network If several Controllers are used in a system a centralized intelligent server Centralized Wireless Management can be used for administration and management 2 2 RF Modulation Standard 2 2 1 802 11b g RF Modulation Standard WLAN products based on the 802 11b g standards operate in the 2 400 to 2 497 GHz frequency range which is one of the Industrial Scientific Medical ISM bands This is an un licensed frequency band also used by Bluetooth devices medical equipment and many other devices that do not require a license The frequency band is divided into channels on which data packets are sent in parallel It is important that the channels do not overlap each other as this would decrease the performance of the network APs supporting the 802 11b g standard have up to 14 channels with centre frequencies that are 5 MHz apart applies to channel 1 to 13 Since the bandwidth of each channel is either 22 MHz 802 11b or 20 MHz 802 118 the centre frequencies for non overlapping channels must be at least 25 MHz apart This gives us three non overlapping channels at the most see the example with 11 channels in figure 4 These channels are reus
7. created an interim security standard called Wi Fi Protected Access WPA WPA is designed for securing data and that access to the networks will be restricted to authorized users WPA is 802 1X in combination with TKIP Temporal Key Integrity Protocol TKIP is a more secure protocol than WEP and provides several enhancements for example a key mixing function a message integrity check and a re keying mechanism that rotates keys faster to prevent sniffer programs from decoding the keys WPA comes in two versions WPA Enterprise and WPA Personal WPA Enterprise is designed for use with an 802 1X authentication server Before getting access to the network the mobile device must provide credentials to a security server RADIUS server The security server authenticates the credentials to verify that the mobile device is known by and authorized to access the network WPA Personal is a Pre Shared Key version WPA PSK intended for use in SOHO small office home office wireless networks that cannot afford the cost and complexity of an 802 1X authentication server 2 3 5 WPA2 While WPA is a subset of 802 11i the Wi Fi Alliance refers to their approved interoperable implementation derived from 802 11i as WPA2 WPA2 specifies security mechanisms for WLANs and supersedes the previous security specification WEP WPA2 details stronger encryption authentication and key management strategies for wireless data and system security and is bet
8. of pocket units at the end customer site or anyone interested to get deeper usage knowledge For PC Software If it is preferable to separate installations and operations a UM describes how the end user operates the software In many cases UM is complemented with on line help Target groups End user 7 September 2011 Ver G 33 System Description Ascom VoWiFi system TD 92313EN On Line Help OH Gives help and information via the PC screen Repair Manual RM For service and repair on some of the Ascom products The document describes the repair of a product defined by one of three levels 1st Line Repair Mechanical cosmetic repair such as change of housing etc and upgrade of software No advanced soldering knowledge is needed but test equipment to verify functionality quality after repair is needed Could also include test programming equipment for field onsite service 2nd Line Repair Electrical repair on PCB level changing of PCBs minor electrical repair of PCB level and change of easily soldered parts Test equipment to verify functionality quality after repair is needed 3rd Line Repair Advanced electrical repair on PCB level Major knowledge in soldering technique is needed Changing of SMD BGA circuits etc Advanced test equipment and equipment to verify functionality quality after repair is needed Target groups service and support technicians Assembly Card AC Delivered with a product Shows how
9. optional element of WMM The TSPEC feature helps ensure predictable voice quality and encourages roaming by managing the total voice load on the AP Call Admission Control CAC keeps the number of active voice calls from exceeding the configured limits of an AP With this feature phones are always connected to an AP but not necessarily on an active call This helps ensure that the voice quality of existing calls is maintained TSPEC describes characteristics of traffic streams such as data rate packet size delay and service interval and provides the mechanism for controlling admission establishment adjustment and removal of traffic streams If data traffic is overloading a link in the network it can be delayed or even dropped and re sent Voice traffic cannot be handled the same way since real time traffic such as voice is sensitive to both latency and packet loss and it would jeopardize the QoS expected by the users CAC determines whether the required network resources are available to provide suitable QoS for a new call before the new call is placed 2 4 4 WMM Power Save WMM Power Save is a set of features for WiFi networks that increase the efficiency and flexibility of data transmission in order to conserve power WMM Power Save has been optimized for mobile devices running latency sensitive applications such as voice audio or video but can benefit any WiFi device WMM Power Save uses mechanisms included in the IEEE 802 11e sta
10. products that are based on the Institute of Electrical and Electronics Engineers IEEE 802 11 standards Today most people use WiFi as a reference to wireless connectivity System Description Ascom VoWiFi System TD 92313EN WLAN Wireless Local Area Network LAN a type of LAN in which data is sent and received via high frequency radio waves rather than cables or wires WMM Wi Fi Multimedia offers QoS functionality for WiFi networks WPA Wi Fi Protected Access a set of security features for wireless networks based on IEEE 802 111 WPA2 Wi Fi Protected Access 2 adds additional security features the most important of which are pre authentication which enables secure fast roaming and AES which is the new FIPS standard for data encryption a The Wi Fi Alliance develops universal specifications facilitates testing and grants interopera bility certification for Wi Fi equipment from a wide range of manufacturers across product lines 7 September 2011 Ver G 5 System Description Ascom VoWiFi System TD 92313EN 2 WLAN A Wireless Local Area Network WLAN uses radio frequency RF technology to transmit and receive data over the air To enable transmission of such different types of communication as data and voice it is essential that hardware and software comply to specified standards The Institute of Electrical and Electronics Engineers IEEE have established the IEEE 802 11 standard which is the m
11. to mount or assemble some part for example a battery back Leaflet LE Usually delivered with a product Can be safety and regulatory instructions how to start up a product or other important information 7 September 2011 Ver G 34
12. users Shared Phones functionality means that a user can log on off on any pre subscribed VoWiFi Handset in the system and synchronize with the settings in the Device Manager to get individual user settings such as volume alarm parameters and local phonebook 7 September 2011 Ver G 24 System Description Ascom VoWiFi system TD 92313EN Handset Administration gives the possibility to list all VoWiFi Handsets and search for VoWiFi Handsets that are registered in the system and to see and or change the absent status of the VoWiFi Handset The Network Time Protocol NTP built in server makes it possible to synchronise the time in the whole system The Open Access Protocol OAP enables exchange of data between systems and makes messaging from customised applications possible Messaging Groups is used when one message should be sent to several VoWiFi Handsets There are 30 groups with up to 15 users in each group and 1 group with up to 50 users A more advanced group handling requires an ESS module System 900 Interface connects directly to the system bus in System 900 and can control the communication on the bus If no messages are sent on the system bus the central unit in system 900 can be excluded LAN Interface is the connection to the Ethernet Every IMS3 supports from start depending on the chosen licenses Basic one way messaging Messages with delivery receipt automatic acknowledge e Messages with manual ackn
13. 400 ns 0 1 BPSK 1 2 6 50 7 20 13 50 15 00 1 1 QPSK 1 2 13 00 14 40 27 00 30 00 2 1 QPSK 3 4 19 50 21 70 40 50 45 00 3 1 16 QAM 1 2 26 00 28 90 54 00 60 00 4 1 16 QAM 3 4 39 00 43 30 81 00 90 00 5 1 64 QAM 2 3 52 00 57 80 108 00 120 00 6 1 64 QAM 3 4 58 50 65 00 121 50 135 00 7 1 64 QAM 5 6 65 00 72 20 135 00 150 00 8 2 BPSK 1 2 13 00 14 40 27 00 30 00 9 2 QPSK 1 2 26 00 28 90 54 00 60 00 10 2 QPSK 3 4 39 00 43 30 81 00 90 00 11 2 16 QAM 1 2 52 00 57 80 108 00 120 00 12 2 16 QAM 3 4 78 00 86 70 162 00 180 00 13 2 64 QAM 2 3 104 00 115 60 216 00 240 00 14 2 64 QAM 3 4 117 00 130 00 243 00 270 00 15 2 64 QAM 5 6 130 00 144 40 270 00 300 00 16 3 BPSK 1 2 19 50 21 70 40 50 45 00 17 3 QPSK 1 2 39 00 43 30 81 00 90 00 18 3 QPSK 3 4 58 50 65 00 121 50 135 00 19 3 16 QAM 1 2 78 00 86 70 162 00 180 00 20 3 16 QAM 3 4 117 00 130 00 243 00 270 00 21 3 64 QAM 2 3 156 00 173 30 324 00 360 00 22 3 64 QAM 3 4 175 50 195 00 364 00 405 00 23 3 64 QAM 5 6 195 00 216 70 405 00 450 00 24 4 BPSK 1 2 26 00 28 90 54 00 60 00 25 4 QPSK 1 2 52 00 57 80 108 00 120 00 26 4 QPSK 3 4 78 00 86 70 162 00 180 00 27 4 16 QAM 1 2 104 00 115 60 216 00 240 00 28 4 16 QAM 3 4 156 00 173 30 324 00 360 00 29 4 64 QAM 2 3 208 00 231 10 432 00 480 00 30 4 64 QAM 3 4 234 00 260 00 486 00 540 00 31 4 64 QAM 5 6 260 00 288 90 540 00 600 00 802 11n is backwards compatible with existing 802 11a b g networks legacy networks However mixing 802 11n devices with legacy devices will
14. 7 161 X ISM 5 825 5 875 1 165 X 1 mm ment V gi ee DIUI IIT gt g Figure 5 The UNII band with 24 non overlapping channels 2 2 3 802 11n RF Modulation Standard gi 3 gis mimi The 802 11n standard improves the reliability of communications the predictability of coverage and the overall throughput It uses the same frequency bands as 802 11b g and 802 11a This means that WLAN products based on the 802 11n standard can operate in the 2 4 GHz band the 5 GHz band or both 802 11n devices can use Multiple Input Multiple Output MIMO This means that they can use more than one radio chain to transmit and receive The standard defines configurations from one transmit and one receive radio chain 1x1 up to four transmit and four receive radio chains 4x4 MIMO can be used in several ways e Spatial division multiplexing A transmitter breaks down the signal stream into multiple streams and transmits the streams using multiple antennas spaced a short distance apart This creates a difference in the multipath images for each stream The receiver can therefore distinguish the individual streams and put them back together thereby increasing the overall data rate of the system 7 September 2011 Ver G System Description Ascom VoWiFi System TD 92313EN Space time block coding A transmitter uses more antennas than signal streams to redundantly transmit the transmit sig
15. AP While the autonomous APs carry out all wired to wireless packet format conversion encryption QoS application and RF statistics monitoring the very thinnest APs pass all of this to their central controller and act basically just as a media converter 2 1 1 Autonomous Access Points ES qup e Figure 2 Autonomous APs connected directly to the LAN The example in figure 2 shows a system with autonomous APs This is the most basic type of a WLAN in Infrastructure Mode The individual autonomous APs handle all traffic handling authentication RF management and mobility functions They are entirely independent of each other and have to be configured separately 7 September 2011 Ver G 6 System Description Ascom VoWiFi System TD 92313EN 2 1 2 Controller Based Access Points Centralized Wireless Management Controller Controller Figure 3 Controller based APs with centralized management LAN The example in figure 3 shows a system with controller based APs With this approach APs can share the features that enhance wireless communications Much of the configuration is centralized in the Controller The Controller handles switching functionality to the WLAN security functionality RF management QoS and extended roaming features It is physically connected to the LAN and not to the APs It is also possible to use a Controller that incorporates a switch The APs are then directly
16. Ascom User Documentation This appendix explains the technical documentation structure and gives a description of each document type Not all document types exist for all systems System documents 1 System Description SD 2 System Planning SP 3 System Installation SI Function Description FD Describes functions on system and product level and requirements to achive them Configuration Manual CM Settings for Products Configuration Notes CN Settings for interconnection with other products Troubleshooting Guide TC For products and systems Product documents Data Sheet DS User Installation Installation ELI Manual Guide IG and Operation quM Manual IOM Portable Devices Fixed units Software PC software ld ner Assembly Card AC Quick Reference Guide QRG Producte Service documents Portable Devices only Leaflet LE For products and important informati Repair Manuals RM 1st 2nd and 3rd line I 00 Portable Devices Fixed Units Figure 15 Documentation structure System Description SD Gives a general description of the system philosophy with basic functions and general configuration po
17. Manager Messaging Tool Basic Alarm Manager Central phonebook Handset Registration Authentication Shared Phones Handset Administration igi cic oe ae Ethernet port LAN Interface e VoWFi lcm ume Sygem 900 eens y i System 900 Interface Figure 11 IMS3 functions The Device Manager makes it possible to remotely edit parameters and update software in the VoWiFi Handsets over the air It contains a database with all device settings It can manage large sets of devices that are identical apart from their call numbers IMS3 contains support for messaging and alarm and includes basic versions of customer tools such as a web based Messaging Tool and Basic Alarm Manager BAM A more advanced alarm handling requires an AMS or an XGate module The Central Phonebook contains 500 entries in an internal database These entries has to be manually entered Alternatively the Central Phonebook can contain 2000 entries that are imported from an external source via CSV file import These entries contain less information since they are restricted by the import format It is also possible to let the Central Phonebook forward a request to an LDAP server Handset Registration Authentication in the IMS3 is needed for the messaging function A password used for authentication can be specified in the IMS3 and used for all VoWiFi Handsets in the system or the IMS3 can retrieve individual passwords from a User Server for example an ESS with defined
18. PDM TD 92325EN Installation and Operation Manual IMS3 TD 92762EN Installation and Operation Manual Unite Connectivity Manager TD 92735EN Installation and Operation Manual VoIP Gateway TD 92326GB Installation and Operation Manual Phonebook Service TD 92360GB 7 September 2011 Ver G 29 System Description Ascom VoWiFi system TD 92313EN 9 Document History For details in the latest version see change bars in the document Version Date Description A 4 July 2006 First version B 10 November 2006 Added WLAN features in i75 VoWiFi Handset C 21 October 2007 The following are added 2 4 3 TSPEC Call Admission Control on page 16 2 3 6 Proactive Key Caching Opportunistic Key Caching on page 14 e 2 6 802 11h on page 16 New supported standards and features in i75 VoWiFi Handset Appendix A Ascom User Documentation on page 32 D 26 September 2008 e Added information about Device Management on page 26 Added information about location in chapter 7 Connection to Other Systems on page 27 Added a location server to figure 1 figure 12 and figure 11 Added new documents to chapter 8 Related Documents on page 29 E 13 November 2009 Added note about speech time and battery life time 2 4 4 WMM Power Save on page 16 F 13 December 2010 e Updated the infrastructure description in chapter 2 1 WLAN Infrastructure on page 6 Added 802 11a and 802 11n in chapter 2 2 RF Modulat
19. TD 92313EN System Description Ascom VoWiFi System 7 September 2011 Ver G System Description Ascom VoWiFi System TD 92313EN Contents 1 IntroductiOH sc sccscescessesccussccessssvecsessessecsosscesooseosendeedsedeseusdsnescoscescavestestectenstecselsescsdessssoss d N 1 1 Abbreviations and Glossary essessoonsssnsennuensnsennesssnnsenssssnnnessnnsennsssensennesssnnsssenssnnuenene 2 1 WLAN Infrastruct re sississccessesscsccssassensecvansensessecsenvecssasssvensenscosbensensosdecsensscseessesesssnss 2 1 1 Autonomous Access POINTS ceesesooneeessnnsenssnnsesssnssensonnenssnnsenssnnsenssnssenssnnsssssnsnnse 2 1 2 Controller Based Access POINTS sssssccocsosesessesscssedsssssssccoessessessocsesscoscescessssseese 2 2 RF Modulation StANGALAsessciscccasicocascscaccesssnedecssacstessodesssnsnscunssecesessssesnecessecsscseseessses 2 2 1 802 11b g RF Modulation Standard ccsccsccssesccscesscsscsscsscescsscsessessessesseees 2 2 2 802 11a RF Modulation Standard cce eee eee ee eee eee eene eee eee enses ette eeetnoo 2 2 3 802 11n RF Modulation Standard ee eeeeee eee eeeeeee eese eeeeeeeoeeeeeseeeeees I oO N NN DD O 2 3 Access Control and Security eee eee eee eee ee eee eene neenon se ens cesses eesessessseesseeessess LZ 2 3 1 ESSID Extended Service Set Identifier ceres eeee eee eee enne eese eeeess 1 2 2 3 2 MAC Address Filtering ecce e
20. The MAC address filtering is only used for authentication of clients in the system and provides no encryption of traffic on the network 7 September 2011 Ver G 12 System Description Ascom VoWiFi System TD 92313EN 2 3 3 WEP WEP is a security method built into the 802 11 protocol It uses a shared key system this means to configure a key basically a password in the AP In order for a wireless client to connect to the network they must know the key and type it into their software The WEP standard allows for 64 bit and 128 bit security keys also referred to as 40 bit or 104 bit to be entered in both APs and mobile devices With WEP encryption the transmitting device encrypts each packet with a WEP key and the receiving device uses that same key to decrypt each packet The encryption method used is RC4 Cipher A problem with WEP is that key management is not specified by the standard and therefore often neglected WEP is simple and it also provides link encryption which keeps the data safer from people snooping on it To remove access from someone the only way to do it is to change the shared key This means breaking everybody else that is using the WLAN and new keys have to be distributed WEP has shown to have security weaknesses and is therefore not recommended 2 3 4 WPA To improve 802 11 security as an intermediate solution to WEP insecurities until the IEEE organization ratified the 802 11i standard the Wi Fi Alliance
21. ally some hours Now when the mobile device wishes to handover it can bypass the whole 802 1X re authentication sequence by presenting its cached PMK The authenticator will recognize the PMK and move straight to the next step deriving session keys 2 3 6 Proactive Key Caching Opportunistic Key Caching Even with key caching described in section 2 3 5 WPA2 a mobile device must authenticate with each AP it wishes to get service from Even though this event only needs to occur once for each AP for as long as the keys are considered valid and are cached on both the mobile device and the AP it introduces significant latency and overheads To resolve this issue the so called Proactive Key Caching PKC also called Opportunistic Key Caching was designed PKC allows a station to re use a PMK it had previously gained through a successful authentication process with the first AP eliminating the need for the station to authenticate against new APs when roaming When a mobile device moves from one AP to another AP the client re computes a PMKID using the previously used PMK and presents it during the association process The Controller will search its PMK cache to determine if it has such an entry If it does it will by pass the 802 1X authentication process and immediately initiate the WPA2 key exchange If it does not it will go through the standard 802 1X authentication process Proactive Key Caching is vendor specific but work is underw
22. ay to develop a standard 2 3 7 Certificate Based Authentication The authentication security can be improved using certificates A certificate is issued by a certification authority to validate the identity of the owner of the certificate Any party wishing to validate the certificate uses a root certificate that identifies the certification authority The following authentication protocols that are compliant with 802 1X and Extensible Authentication Protocol EAP use certificate based authentication Protected EAP Microsoft Challenge Handshake Authentication Protocol PEAP MSCHAPv2 The network has a certificate and the mobile device has a root certificate that it uses to check that the network s certificate is valid thereby ensuring that he network is trusted e EAP Transport Layer Security EAP TLS The network and the mobile device has a certificate each and they both have the common root certificate The mobile device uses the root certificate to check that the network s certificate is valid thereby ensuring that the network is trusted If so the network uses its root certificate to check that the mobile device s certificate is valid thereby ensuring that it is authorized to access the network EAP TLS is more secure than PEAP MSCHAPv2 but requires that all mobile devices have unique certificates 7 September 2011 Ver G 14 System Description Ascom VoWiFi System TD 92313EN 2 4 Quality of Service QoS Without QoS a
23. cascessoscescoseseosecasssvessseteosessusteceesecasvetecsessaseesedetastessecssensonsisccettessestetet Oo 5 4 RADIUS Server ccccccccssccrsssssccccccsccssssssccccsccscccssessssssseccccccsssssssssccsscssssssscesssssccccses 24 5 5 Integrated Wireless Messaging and Services IMS3 crees 24 5 6 Unite Connectivity Manager Unite CM eee eee eene eee eee eee eee eese eeessessessesses 20 5 7 Portable Device Manager PDM aesscsnesuesuensesnensessessesssonsonsonsonsonsonuennennensessessessreneen 20 SEMBLE HSVEPPICEWSIXS RERBA S 5 9 SIP PrOXY SOLVE icessessnssossensessecvadsessensocseonssesuacsoesenssescssacsecsecseceadetessassocssassessssessete 27 sae 3 l 6 Administration Tools ssecceccssssecossscssoeccsssscccecessssccceeessssocossscosoecesssseccoecessssocssessssseees 27 7 Connection to Other Systems uessessossnsssonssusssnsssnssnnssonsnnssnsssnnssnnssnsssnssonenonsnensnnssnnsene 27 7 1 System Solution When Connected to IP PBX cusssssonssonssonsnsssnnssnnsnnsssnsnonssnnennnennne 28 7 2 System Solution When Connected to Traditional PBX e sessessesoesossosoesossessesoesoesoee 28 8 Related Documents eissssccscsccccccscessccsesscsscvsvsensssossesnctevsscssessnvecscesssesssenssoosseseseessoscssartce 29 9 Document History eere eese eese eee eene seen sse sns osos soose sassis seneso a JU Appendix A Ascom User Documentation essessssnsssnssonssonssonenonensnsnensnnnsnssonssonenunesu
24. ctions in other ELISE3 applications such as ESS functions for user and group administration escalations remote management connectivity surveillance supervision activity logging and fault logging For a detailed description of the Unite CM see Installation and Operation Manual Unite Connectivity Manager TD 92735EN 5 7 Portable Device Manager PDM The PDM is a management tool for the VoWiFi Handsets It makes it possible to edit parameters and update software in a VoWiFi Handset on site It contains a parameter database holding system parameters as well as parameters specific for the VoWiFi Handsets The PDM is a software application that runs on a local Windows PC and communicates with the VoWiFi Handsets by means of a USB connection One VoWiFi Handset at a time has to be physically connected to the PC via a VoWiFi Handset cradle with a USB cable a Desktop Programmer DP1 The PDM has a Java based Graphical User Interface The PDM is always used for the initial site specific configuration of the VoWiFi Handsets It can then for future settings be replaced by an IMS3 Unite CM for individual settings and for management of the VoWiFi Handsets For a detailed description of PDM see also Installation and Operation Manual Portable Device Manager PDM TD 92325EN Figure 12 Desktop Programmer DP1 connected to a pc running PDM 5 8 VolP Gateway Gatekeeper The VoIP gateway serves as a link between traditional telephony con
25. ds eese eere eese eene essen nete senes ense enses sese sese sesesssesssesseessees 20 4 1 1 VoWiFi Handset cessere esee eee eene eene ene en etes ees eene essen eiiaoe aiseee osseo 20 4 2 System FUNCTIONS ceres eese eene eene eee tenen seta sens s ense enses ssese sese sesesnsesssesseessees 20 7 September 2011 Ver G System Description Ascom VoWiFi system TD 92313EN 4 3 WLAN FUNCTIONS sessnssonssonesonsnnnsnnssnnssnnsnnsnsnssonsnnnsnnnsnssnnnsnnnssnsnnnsnnnsnnnsnnnsnnnsnnsnnnsnnnsne 21 4321 rm 21 4 3 2 ASSOCIATION RR 21 4 3 3 AuthenticatioNn ssassossonssonssnnsnssonsssnsnsnssnsssnssnnsnnnsnnssonsnnnsnnnsnnnsnnnsnnnsnnsnnnsnnnsne 21 4 4 Network Parameter Download ee eee creen eene eere senes eene esses eesseeesseessseeeesesses 22 4 5 Supported Third Party Products eese entente eene eene eene enses esesnsesnseenneenn 22 4 6 WLAN Planning and Deployment for Ascom VoWiFi System sesessesesososossesosossesoe 22 5 Ascom VoWiFi System Components essesssssonessssnssonssssenossnessnnssnnssnssonensnensnenensnesunese 23 5 2 NOWIFIHANGSECT ecsnrveesxcsncdsesasecssntesdconssssetesessedscsscssessrssnsenserscessecnessrdersesdsetesseetess s 23 5 2 Access POI AP cecessessssseescasesvesdeasensectesseossesenssnescoeces cosdnsssesuccesessusseassoasssel saverses 23 Ded COMEMOMET csccseses
26. ed and allocated to APs in different regions one channel per AP Use of other channels than 1 6 and 11 will have a major negative impact on performance in the system since those channels will interfere with each other Not only due to RF interference but also due to the 802 11 protocol specification a selection of channels other than 1 6 and 11 will cause a performance reduction 1 The centre frequency in channel 14 differs from the other 12 MHz apart It was previously used only in Japan 7 September 2011 Ver G 7 System Description Ascom VoWiFi System TD 92313EN The 802 11b and 802 11g specifications include the following restrictions Radio Band 2 4 GHz Maximum Data Rate 11 Mbps 802 11b 54 Mbps 802 11g Operating channels 1 14 depending on country regulations ETSI 1 13 FCC 1 11 Maximum number of non overlapping channels 3 Typical Indoor Range 30 m 100 ft Typical Outdoor Range Line of Sight 120 m 400 ft a With basic antenna and maximum power level 4 7 9 2 2417 7 2442 2457 2484 2 4 5 10 12 43 241 2422 2427 2432 2 2447 24 2457 2452 2467 QA i LI i MC g 5 Cl E o Sr Fe 0 Se E 0 E 3 2 0 Figure 4 The 2 4 GHz band with three non overlapping channels 1 6 and 11 2409 ARROW Limi The standard specifies data rates up to 11 Mbps for 802 11b and 54 Mbps for 802 11 but this must be considered as a theoretical maximum only
27. ere encre eerte eene een eene ens se sense eseseesseessseeess 1 2 TM 13 2 3 6 Proactive Key Caching Opportunistic Key Caching mMA 14 2 3 7 Certificate Based Authentication crssssoseonsonennsnnsnnssnssnssnnsnssnnsnnsnnsnnsnnsnnennsnnnene 14 2 4 Quality of Service QOS erenssssnssnesssnennsnssnennsnssnsnssnssnsnnsnssnsnssnsnnsnssnsnssnnsnsnnssssnsnnsnnenee 15 2 4 1 SB O21 Les A E O EE E ENNE E O O LD 242 WMM WME is sceccecsusscceccecectencuncastacaasecectastaausosccasosacessessesabodbeddadeeseascessences LD 2 4 3 TSPEC Call Admission Control e eesessesoesossessessosoosoesossesoesoosossosoeesesoesossossesossseso LO 2 4 4 WMM Power Save eese eene eee eene enses n sees eene se sens sen serasa asise LO 2 5 Cisco Compatible Extensions CCX eesessessesnesnenuessesnesnsensensensessensessesnennensessesunsunenee LO 3 VOWiFi a rA 3 1 VOIP Signalling Protocols eere eret eerte stese ssena cosu etes enssensssnsssssseseseses L7 3 1 2 H 450 Supplementary Services for H 323 crescentes 17 3 1 3 Session Initiation Protocol SIP ccsscececcsossessccsessccdeccecsccesccdcessctsessctccscsssessesens 1 7 3 2 VoWiFl Standards 5 eee eee resa so eee pete etae than aeo Pee Pe erra sae ee Erano area ceet se co see b rrasaPse ee LO 4 Ascom VoWiFi System Overview eeeee eee ee eene eene neenon esee sese eeseeeseeeseesesss 18 4 1 Supported Standar
28. erlapping 40 MHz channels ETSI 9 FCC 11 Typical Indoor Range 30 m 100 ft Typical Outdoor Range Line of Sight 100 m 330 ft a With basic antenna and maximum power level A BN 64 5320 5240 15300 LJ ts ee eT TTT TT es Ls a p E T nd 0a 2 J 115 120 24 2H 3 5540 8860 5840 5600 wm Y oo lE LLLA LLL LLL LLL OTTI 4 BY 7 G g 4n 49 5 5 81 T ITT LLLA LLL LLL LU i ES Gap e Al i i J 7 gt 7 6 1 m fs TTT 8 J amu i D idi s E Figure 6 20 MHz and 40 MHz channels in the 2 4 GHz and 5 GHz bands 7 September 2011 Ver G 10 System Description Ascom VoWiFi system TD 92313EN The 802 11n standard defines Modulation and Coding Scheme MCS which is combinations of modulation Forward Error Correction FEC coding and number of spatial streams The maximum data rate depends on the MCS channel bandwidth and GI length There are 77 MCS values from 0 to 76 The first 32 MCSs are shown below The rest are mixed combinations that can be used to modulate two to four streams 802 11n stations must support values 0 7 and 802 11n APs must support MCS values 0 15 MCS Number of Modulation and Data Rate Mbps Data Rate Mbps Index streams FEC Coding 20 MHz Channel 40 MHz Channel GI 800 ns Gl 400 ns GI 800 ns GI
29. fines how to send data from one device to another over the wired and wireless media ISM Industrial Scientific Medical ITU International Telecommunications Union Jitter Variation in latency among a group of packets sent between two nodes Latency The total time for a data frame to travel from a sender to a receiver Medium Access Control address a unique identifier attached to most forms of computer networking equipment Modulation and Coding Scheme Multiple Input Multiple Output The receiver does not only contain a direct line of sight radio wave but also a larger number of reflected radio waves Protected Extensible Authentication Protocol Microsoft Challenge Handshake Authentication Protocol Private Branch Exchange telephone system within an enterprise Portable Device Manager Used for management of portables editing of parameters and updating the portables with new software Primary Rate Interface Push To Talk System Description QoS QPSK RADIUS RF Roaming RSVP RTCP RTP RTSP SAP SDP SIP SOHO TDMA TPC TSPEC UNII Unite Unite CM VoIP VoWiFi WEP WiFi 7 September 2011 Ver G Ascom VoWiFi System TD 92313EN QAM Quadrature Amplitude Modulation 16 QAM has 16 possible signal states with each symbol representing 4 bits 64 QAM has 64 possible signal states with each symbol representing 6 bits Quality of Service defines to what extent transmission rates error rates etc
30. ignalling information to control the supplementary services such as Call Transfer Call Diversion Call Waiting etc over a LAN 3 1 3 Session Initiation Protocol SIP SIP is an application layer control signalling protocol for creating modifying and terminating sessions with one or more participants These sessions include Internet multimedia conferences Internet telephone calls and multimedia distribution SIP is designed as part of the IETF standards 7 September 2011 Ver G 17 System Description Ascom VoWiFi System TD 92313EN SIP itself is not sufficient to set up a call and other IETF protocols such as RSVP RTP RTSP SAP and SDP are required to support a VoIP call However the functionality and operation of SIP does not depend on any of these protocols 3 2 VoWiFi Standards The most basic VoWiFi system supports the following WLAN standards e EEE 802 11b or IEEE 802 11b g for Wireless LAN e WMM for voice quality QoS e One of ora selection of WPA and WPA2 for security e H 323 or SIP with or without supplementary services H 450 RFC s for telephony 4 Ascom VoWiFi System Overview To enable an enterprise VoWiFi system where voice traffic as well as messaging and alarm handling are possible both Ascom and third party developed hardware and software are used A basic system comprises the following products e VoWiFi Handset e Access Point AP e Portable Device Manager PDM Controller optional
31. ion Standard on page 7 e Added multiple ESSIDs and hidden ESSIDs in chapter 2 3 1 ESSID Extended Service Set Identifier on page 12 Added chapter 2 3 7 Certificate Based Authentication on page 14 e Removed PDM System Version and replaced WLAN Switch Appliance with Controller in chapter 4 Ascom VoWiFi System Overview on page 18 Added supported standards for i62 VoWiFi Handset and updated those for i75 VoWiFi Handset in chapter 4 1 Supported Standards on page 20 Added i62 VoWiFi Handset in chapter 5 1 VoWiFi Handset on page 23 Replaced WLAN Switch Appliance with Controller in chapter 5 3 Controller on page 23 Replaced IMS IP WiFi with IMS3 in chapter 5 5 Integrated Wireless Messaging and Services IMS3 on page 24 Added chapter 5 6 Unite Connectivity Manager Unite CM on page 26 e Removed PDM System Version in chapter 5 Ascom VoWiFi System Components on page 23 Replaced PDM Windows Version with WinPDM in chapter 5 7 Portable Device Manager PDM on page 26 Added chapter 5 9 SIP Proxy Server on page 27 7 September 2011 Ver G 30 System Description Ascom VoWiFi System TD 92313EN Version Date Description G 7 September 2011 Removed all information related to the i75 handset Replaced IMS2 with IMS3 Replaced WinPDM with PDM Minor text and layout changes 7 September 2011 Ver G 31 System Description Ascom VoWiFi System TD 92313EN Appendix A
32. iption Ascom VoWiFi System TD 92313EN 4 3 WLAN Functions Common WLAN functions such as roaming and user authentication are handled by third party products Therefore specific configuration information must be required from the vendors For details see Ascom Configuration Notes for third party products 4 3 1 Roaming To enable a user to move freely within the WLAN see section 5 2 Access Point AP on page 23 careful cell planning must be performed before installation of the APs Each AP provides radio coverage for a certain area a micro cell Since radio coverage is declining as the user moves farther away from the AP it is important that the cells overlap In a WLAN with multiple APs users can move freely once they have associated and authenticated themselves to the network This means that mobile devices will move in and out of range of the various WLAN cells searching and associating with the strongest RF signal as they move across the network From an IEEE 802 11 perspective WLAN roaming consists of the following steps 1 Search 2 Pre authentication if key caching is used otherwise authentication 3 Re association 4 3 2 Association Before the authentication can take place the mobile device need to be associated with an AP Each AP in the network transmit beacons that the mobile devices listens to The mobile device in this case a VoWiFi Handset sends an association request to the AP with the strongest RF signal By
33. ler delivers Wireless LAN services over an existing Ethernet or IP infrastructure Dynamic Frequency Selection Delivery Traffic Indication Message Extensible Authentication Protocol EAP Flexible Authentication via Secured Tunnel System Description MAC address MCS MIMO Multipath PEAP MSCHAP PBX PDM PRI PTT 7 September 2011 Ver G Ascom VoWiFi System TD 92313EN EAP TLS EAP Transport Layer Security ESS Enhanced System Service Unite modules that handle centralised number planning remote connection system supervision fault handling group handling message routing centralised logging activity logging and user access administration ESSID Extended Service Set Identifier ETSI European Telecommunications Standards Institute a European standards organization charged with defining standards for EC countries FCC Federal Communications Commission FCC the primary interstate regulatory authority for telecommunications and radio systems for the US FEC Forward Error Correction GI Guard Interval Handover The process of moving a VoWiFi Handset from one AP to another during an ongoing call IEEE Institute of Electrical and Electronics Engineers IETF Internet Engineering Task Force IMS3 Integrated Wireless Messaging and Services a Unite module that enables wireless services to and from the VoWiFi Handsets in a WLAN system It also includes the Device Manager IP Internet Protocol a global standard that de
34. ll applications running on different devices have equal opportunity to transmit data frames This works well for data traffic but voice and other multimedia in a WiFi network is highly sensitive to latency increases and throughput reductions and require QoS functionality When deploying a VoWiFi system traffic prioritization is needed to ensure the best possible voice quality QoS for a WLAN enables the AP to prioritize traffic and optimizes the way shared network resources are allocated among different applications It is defined as the control of bandwidth latency jitter and traffic loss 2 4 1 802 11e The 802 11e specification adds QoS to WLANs by defining how data voice video and audio transmissions should be prioritized in the radio channels The standard also specifies enhanced error correcting mechanisms in the Media Access Control MAC layer to improve the voice traffic which is very delay sensitive The amendment 802 11e is dealing with QoS issues and two different access mechanisms are defined EDCA and HCCA e Enhanced Distributed Channel Access EDCA is dealing with QoS by prioritization This means that some kind of data voice is given a higher priority but does not guarantee any quality of the call Hybrid Controlled Channel Access HCCA makes use of a central coordinator that allocates transmission opportunities to clients dynamically based on bandwidth needs and the service interval required This is an approach t
35. ls are detected TPC reduces the radio frequency RF output power of each network transmitter to a level that minimizes the risk of interference to and from other systems while still allowing satisfactory network performance 7 September 2011 Ver G 16 System Description Ascom VoWiFi System TD 92313EN 3 VoWiFi 3 1 Voice over Wireless Fidelity VoWiFi is a wireless based VoIP service Where VoIP consists of the hardware and software that enables people to use the Internet Protocol as the transmission medium for telephone calls VoWiFi is the wireless version of this technology which is designed to work on wireless devices The voice signal is digitized compressed and converted to IP packets and then transmitted over the network Since voice is a real time application a VoWiFi system must ensure that the data streams are reconstructed accurately and that sufficient mechanisms for network delay detection have been implemented VoIP Signalling Protocols Two of the protocols used for voice over IP VoIP signalling are H 323 and the Session Initiation Protocol SIP H 323 was the first standard and is in fact a set of protocols designed to enable multimedia traffic in single LANs One protocol of many in the set of protocols defined in H 323 is H 450 which is a series of protocols that defines Supplementary Services for H 323 Like H 323 SIP can be used for VoIP but while H 323 is ISDN based Q 931 and earlier H series SIP i
36. nal This increases the reliability of the signal at the receiver and reduces the error rate Transmit beamforming A transmitter uses multiple antennas to focus the signal strength in the direction of the receiver This increases the signal to noise ratio at the receiver 802 11n devices can use either 20 MHz or 40 MHz channels The 40 MHz channels are two adjacent 20 MHz channels that are bonded together thereby more than doubling the effective data rate It is possible to have one to two non overlapping 40 MHz channel in the 2 4 GHz band and nine to eleven in the 5 GHz band depending on country regulations 802 11n devices have the option of using a short Guard Interval GI GI is the period of time in between symbols and are used to reduce the interference between symbols 802 11a b g devices use a GI that is 800 ns long but 802 11n devices have the option of using a GI that is either 800 or 400 ns long The 802 11n specification includes the following restrictions Radio Band 2 4 GHz 5 GHz Maximum Data Rate 600 Mbps Operating channels in the 2 4 GHz band Operating channels in the 5 GHz band Maximum number of non overlapping 20 MHz Same as 802 11b g Same as 802 11a 2 4 GHz band 3 channels 5 GHz band 19 24 depending on country regulations ETSI 19 FCC 24 2 4 GHz band 1 2 depending on country regulations ETSI 2 FCC 1 5 GHz band 9 11 depending on country regulations Maximum number of non ov
37. ndard and is an enhancement of IEEE 802 11 legacy power save With WMM Power Save the same amount of data can be transmitted in a shorter time while allowing the WiFi device to remain longer in a low power state Note The battery life time and the speech time are highly dependant on which power save mode that is used We recommend that U APSD is used to achieve optimal battery lifetime Other parameters that can affect the power consumption are Beacon period and DTIM Location in the system will also affect the speech time For more details see the document System Planning Ascom VoWiFi System TD 92408EN 2 5 Cisco Compatible Extensions CCX CCX is a Cisco proprietary collection of functions and requirements Some requirements are just to ensure compatibility with Cisco infrastructure while other features are developed to improve the behaviour of WLAN communication Security and roaming enhancements are worth mentioning as vital parts of CCX 2 6 802 11h IEEE 802 11h amendment was originally developed to extend WLAN operation in Europe to the 5 GHz band where WLAN devices need Dynamic Frequency Selection DFS and Transmit Power Control TPC to coexist with the band s primary users that is radar and satellite systems 802 11h defines mechanisms that can reduce both interference and power consumption DFS detects the presence of other devices on a channel and automatically switches the network to another channel if and when such signa
38. nected via an ISDN PRI interface and IP telephony The VoIP gateway also acts as a gatekeeper enabling call control and call routing The gatekeeper provides network authorization and address translation from an alias H 323 name or E 164 number to an IP address 7 September 2011 Ver G 26 System Description Ascom VoWiFi System TD 92313EN 5 9 SIP Proxy Server When connecting to an IP PBX it is possible to use a SIP Proxy Server in the IP PBX instead of a VoIP gateway gatekeeper It is important to ensure the interoperability between the SIP Proxy Server and the WLAN See the Ascom extranet Sales tools Interoperability 6 Administration Tools Tools for the following VoWiFi functions are defined Network administration VLAN QoS etc in Routers Switches and Access Points User administration PDM and or optional IMS3 Unite CM Call control and call routing Gatekeeper function in the VoIP gateway e Messaging and alarm handling PDM and or IMS3 Unite CM ESS or other Unite modules Administration of these functions are enabled via the tools provided with the VoWiFi components 7 Connection to Other Systems Interoperability with traditional telephony systems is enabled via the VoIP Gateway connected to a main PBX or directly through third party H 323 gatekeeper Interoperability with messaging applications such as the Ascom DECT and Paging system or other external systems such as GSM is done via the Unite s
39. nene 32 7 September 2011 Ver G System Description Ascom VoWiFi System TD 92313EN 1 Introduction The Ascom Voice over Wireless Fidelity VoWiFi system provides wireless IP telephony messaging and alarm functions to enterprise LANs Using third party WLAN products as well as in house developed hardware and software the system enables data and voice transmission together with seamless roaming This document gives a general description of the Ascom VoWiFi solution It briefly describes WLAN and VoWiFi technologies and standards i me Location Server Es Access Point Controller u m VoWiFi Handsets rey Bnrm X Presence anagement System IMS3 Unite CM Unite System ne N EES ZE mmmmm N IP PBX S required equipment optional equipment Figure 1 VoWiFi overview 1 1 Abbreviations and Glossary AES AP BPSK BSS CAC CCKM CCMP CCX Controller DFS DTIM EAP EAP FAST 7 September 2011 Ver G Advanced Encryption Standard Access Point a radio transceiver providing LAN connection to wireless devices Binary Phase Shift Keying Basic Service Set Call Admission Control Cisco Centralized Key Management Counter Mode Cipher Block Chaining Message Authentication Code CBC MAC protocol Cisco Compatible Extensions a Control
40. nnection to other systems and to traditional PBX 7 September 2011 Ver G 28 System Description Ascom VoWiFi System TD 92313EN 8 Related Documents System Planning Ascom VoWiFi System TD 92408EN System Description Unite TD 92243GB Function Description Ascom VoWiFi System TD 92314EN Function Description Device Management in Ascom Systems TD 92479GB Function Description Interactive Messaging TD 92168GB Function Description Shared Phones in Ascom Systems TD 92468GB Function Description Push To Talk in Ascom VoWiFi System TD 92493GB Function Description Location in Ascom VoWiFi System TD 92607GB Function Description Product Licensing Overview TD 92677GB Quick Reference Guide Ascom i62 VoWiFi Handset TD 92597EN User Manual Ascom i62 VoWiFi Handset TD 92599EN Configuration Manual Ascom i62 VoWiFi Handset TD 92675EN Data Sheet Ascom i62 VoWiFi Handset TD 92587EN Data Sheet DP1 Desktop Programmer for Ascom i62 VoWiFi TD 92749EN Handset Data Sheet CR3 Charging Rack TD 92628EN Data Sheet CR4 Battery Pack Charger TD 92630EN Data Sheet Portable Device Manager PDM TD 92324EN Data Sheet Integrated Wireless Messaging amp Services IMS3 TD 92779EN Data Sheet Unite Connectivity Manager TD 92739EN Data Sheet VoIP Gateway TD 92323GB Installation and Operation Manual CR3 Charging Rack TD 92480EN Installation Guide CR4 Battery Pack Charger TD 92724EN Installation and Operation Manual Portable Device Manager
41. o make 802 11 functions like a dynamic TDMA system 2 4 2 WMM WME To meet the need of QoS in products until the ratification of the 802 11e amendment the Wi Fi Alliance9 developed the Wi Fi Multimedia WMM earlier called Wireless Multimedia Enhancement WME to provide QoS in products WMM prioritizes traffic according to four Access Categories AC voice video best effort and background and is based on the Enhanced Distributed Channel Access EDCA method It is important to note that WMM is not an alternative to 802 11e but rather a subset of the standard see section 2 4 1 802 11e on page 15 To take advantage of the functionality in a WiFi network the AP the client device that the application is running on and the source application must support WMM The standard differs from amendment IEEE 802 11e in some respects The EDCA operation and its default values are the same but the coding of the information elements differs The following table shows some of the major differences between 802 11e and WMM 802 11e WMM Enhanced Distributed Channel Access EDCA Yes Yes Hybrid Controlled Channel Access HCCA Yes No Priorities Yes Yes Packet bursting Yes Yes Automatic Power Save Delivery APSD Optional Optional Block ACK Optional No Direct Link Protocol Optional No 7 September 2011 Ver G 15 System Description Ascom VoWiFi system TD 92313EN 2 4 3 TSPEC Call Admission Control This feature supports an
42. on and privacy are independent of each other but are often specified to be used together in some constellations 2 3 1 ESSID Extended Service Set Identifier The ESSID is the identifying name of an infrastructure WLAN Only one ESSID can be specified in the client setup By specifying the ESSID in the client setup it makes sure to connect to the desired WLAN instead of the neighbours WLAN by mistake The ESSID should be unique for each system It is possible to use many ESSIDs for the same WLAN This way different user groups can connect to the same WLAN but get different access rights It is possible to hide the ESSID by not letting the APs broadcast the name That way the users must know the ESSID and enter it manually to be able to connect to the WLAN 2 3 20 MAC Address Filtering MAC address filtering is an authentication method to control who can connect to the WLAN Every wireless card just like an ethernet card has a unique address The administrator creates an Access Control List ACL on the AP with the MAC addresses of the mobile devices allowed to communicate with the AP To enable roaming the ACL must be created on every AP in the network and manually maintain the list Depending on how many clients this may or may not be an issue A weakness is that an unauthorized client can sniff the MAC addresses of authorized clients from the air Also MAC addresses are not as unique as they used to be because they can be changed
43. ost used WLAN standard of today The original version was released in 1997 and over the years several amendments have been added for example IEEE 802 11a IEEE 802 11b IEEE 802 11g and IEEE 802 11n Most of these were merged with the base standard in 2007 except IEEE 802 11n which is a more recent amendment See section 4 1 Supported Standards for a description of the 802 11 amendments supported by the Ascom VoWiFi system 2 1 WLAN Infrastructure There are two types of WLAN topologies the Ad Hoc mode and the Infrastructure Mode The Ad Hoc mode provides peer to peer connectivity where two clients communicate directly with each other via their WLAN cards The Infrastructure Mode on the other hand is used to incorporate the wireless clients into an existing wired LAN infrastructure In the Infrastructure Mode all communication is passed through the Access Points APs that are connected to the wired LAN A single AP communicating with a number of clients is called a Basic Service Set BSS A number of interconnected APs with the same network name is called an Extended Service Set The AP is basically a radio transmitter receiver but depending on hardware and software it can be more or less intelligent An AP that holds information about the mobile clients authorized to enter the system is called an autonomous AP or fat AP whereas an AP that only is responsible for forwarding received data is called a controller based AP or thin
44. owledge e Interactive messaging Erasure of sent messages Mobile data from VoWiFi Handsets Short Messaging Service SMS between VoWiFi Handsets e Personal alarm from VoWiFi Handsets e Central phonebook Alarm handling e Fault logging e Remote management The following functions are achieved license dependent by adding an ESS module e System survey e Fault handling Shared phones with individual passwords The Unite platform makes it possible to connect other Unite modules thereby enabling enhanced system functions see System Description Unite TD 92243GB For a detailed description of the IMS3 see Installation and Operation Manual IMS3 TD 92762EN For a detailed description of the messaging and alarm functions see Function Description Ascom VoWiFi System TD 92314EN For shared phones functionality see Function Description Shared Phones in Ascom Systems TD 92468GB 7 September 2011 Ver G 25 System Description Ascom VoWiFi System TD 92313EN 5 6 Unite Connectivity Manager Unite CM Unite CM is a web based tool used for device management messaging and alarm handling tis also used for the administration of users and groups for supervision activity logging and fault logging It is a Unite module based on the ELISE3 hardware It can be used independently but also work in combination with other Unite modules or System 900 modules Unite CM includes all the functions in IMS3 as well as the fun
45. possible to set the parameters directly on the VoWiFi Handset 4 5 Supported Third Party Products APs Controller and authentication server are examples of third party products required when setting up the WLAN infrastructure The Ascom developed products are designed to work in WLANs provided by different vendors for example Cisco 4 6 WLAN Planning and Deployment for Ascom VoWiFi System Each AP provides radio access within a pre defined area called a cell To enable seamless roaming for the mobile devices cell planning is of most importance when deploying the WLAN Refer to the documentation from the WLAN supplier and System Planning Ascom VoWiFi System TD 92408EN 7 September 2011 Ver G 22 System Description Ascom VoWiFi System TD 92313EN 5 Ascom VoWiFi System Components The Ascom VoWiFi system is created using Ascom developed products as well as third party products This section gives a brief description of the components needed 5 1 VoWiFi Handset The VoWiFi Handset includes functionality such as wireless telephony alarm and messaging The VoWiFi Handset functions are license dependant and are available in three versions Talker Messenger and Protector The VoWiFi Handset is also upgradeable with additional functions via a license In addition to ordinary telephony the VoWiFi Handset supports a push to talk PTT function The PTT function can be described as a group conference call A PTT session can be trigge
46. r and outdoor operation Also the maximum power levels are lower for ETSI than FCC The UNII 2 band s primary users are radar and satellite systems To avoid interference all unlicensed transmitters operating in the UNII 2 band must be able to detect the presence of radar signals and to dynamically and automatically change to a different transmit frequency if radar is discovered see section 2 6 802 11h on page 16 Therefore it is not recommended to use these bands for voice traffic Above the UNII band there is a small part of the ISM band that can be used by 802 11a products as well 5 825 5 875 GHz 7 September 2011 Ver G 8 System Description Ascom VoWiFi System TD 92313EN The 802 11a specification includes the following restrictions Radio Band Maximum Data Rate Operating channels Maximum number of non overlapping channels Typical Indoor Range Typical Outdoor Range Line of Sight 5 GHz 54 Mbps 36 165 depending on country regulations see the table below regulations ETSI 19 FCC 24 30m 100 ft 100 m 330 ft a With basic antenna and maximum power level 19 24 depending on country Radio Frequency Number of Channel numbers FCC ETSI band range GHz channels UNII 1 5 15 5 25 4 36 40 44 48 x x UNII 2 5 25 5 35 4 52 56 60 64 X X UNII 2 5 47 5 710 11 100 104 108 112 116 120 X x Extended 124 128 132 136 140 UNII 3 5 725 5 825 4 149 153 15
47. red from the system by an alarm or by a user that sends an invitation to a PTT group from the VoWiFi Handset Alarms activated from the VoWiFi Handset includes push button alarm and emergency alarm The emergency alarm is triggered when a user calls an external or internal number specified in the system as emergency number Messages can be received in and sent from the VoWiFi Handset The VoWiFi Handset also supports interactive messaging which means that a user can communicate with external sources such as a building management system hospital system or a production process system Interactive messaging can be used for remote control of a machine a door etc The VoWiFi Handset supports presence management making it possible for the user to specify when and for how long the user is busy on a meeting etc The configuration installation and management of the VoWiFi Handset is easily done by means of the Portable Device Manager PDM The VoWiFi Handset can be charged in a desktop charger or a wall mounted charging rack A wall mounted battery pack charger can be used for charging the batteries alone The VoWiFi Handset supports the WLAN standards IEEE 802 11a b g n MCS 0 7 5 2 Access Point AP APs connect the VoWiFi Handsets to the wired network The number of APs in a WLAN installation depends on the size of the area to be covered Each AP provides radio coverage for a certain area called a micro cell To enable a user to move freel
48. result in a significant reduction in throughput for the 802 11n devices 7 September 2011 Ver G 11 System Description Ascom VoWiFi System TD 92313EN 2 3 Access Control and Security Since the physical layer in a WLAN is broadcast over the air the normal methods to control a conventional LAN cannot be used To secure the WLAN from intruders authentication and encryption are important factors Measures like creating a MAC address filter makes it a little more difficult for intruders to access and use the WLAN There are stronger methods such as using authentication for example a RADIUS server but these often require dedicated servers or other hardware The use of encryption does not affect the voice stream when the phone is associated to an AP When roaming between APs the exchange of fresh session encryption keys needs to be completed before transmission of speech frames can be resumed The exchange of encryption keys is time consuming and can cause incidents of silence when roaming Encryption helps to protect the information sent over the air That way an intruder will not be able to snoop on the information that is sent over the air The encryption types used are WEP TKIP and AES Security can be divided in two parts e Authentication ensures that the identities of the two communication peers are correct and can be trusted Privacy aims to protect the communication from eavesdropping by encryption Authenticati
49. rt technicians and system responsible Troubleshooting Guide TG The document provides information that can be useful when analyzing problems in a product or in a system Target groups installation service support technicians and system responsible Data Sheet DS Technical data of a software products etc It includes a short list of features applications and possibly extended functions with other software products Target groups end customer system responsible technical engineers and sales department Installation Guide IG Describes how to install any fixed units in the system Target groups installation and service personnel Installation and Operation Manual IOM Describes how to install and operate different PC software programmes In many cases complemented with or replaced by on line help or CD Target groups service engineer or administration responsible of the end user system Quick Reference Guide QRG This document is available for Portable Devices only It contains a concise how to use description and is normally distributed together with the Portable Device Target groups user of the portable device for quick learning of included functions User Manual UM For Portable Devices Is a complement to the QRG It gives a thorough description of the specific functions and how to use the product for example a Transceiver Target groups responsible for handling the administration and distribution
50. s text based As opposed to H 323 which uses Abstract Syntax Notation number One ASN 1 SIP encodes its messages as text similar to HTTP and SMTP 3 1 1 H 323 H 323 was developed by the International Telecommunications Union ITU and was designed from a telecommunications perspective Ratified in 1996 it has become a defacto choice for interoperability among VoIP equipment It is a standard that provides specification for computers equipment and services for multimedia communication over networks that do not provide a guaranteed QoS H 323 equipment can carry real time video audio and data or any combination of these elements Included in the H 323 standard are H 225 H 245 and the IETF protocols RTP and RTCP with additional protocols for call signalling data and audiovisual communications H 323 products and services offer the following benefits to users Products and services developed by multiple manufacturers under the H 323 standard can interoperate without platform limitations H 323 conferencing clients bridges servers and gateways support this interoperability e H 323 provides multiple audio and video codecs that format data according to the requirements of various networks using different bit rates delays and quality options Users can choose the codecs that best support their computer and network selections 3 1 2 H 450 Supplementary Services for H 323 H 450 is a series of protocols which are used to exchange s
51. ssibilities associated to functions Target groups system responsible at the customer site sales department training department project manager or whoever wants to know the basics of the system System Planning SP Is to be read after taking part of the System Description It describes different functions possible technical system solutions and deals with factors that can affect the installation Target groups technical engineers planning a system 7 September 2011 Ver G 32 System Description Ascom VoWiFi System TD 92313EN System Installation SI Primarily explains system dependent aspects to be considered at system installation and gives an overview of how to install the system Target groups technical engineers planning the system and technicians installing it Function Description FD Gives all relevant information requirements and configuration notes concerning functions in system and products for example positioning interactive messaging etc Target groups see under System Description section Configuration Manual CM Describes the complete configuration for a specific product Target groups installation service support technicians and system responsible Configuration Notes CN Describes required configuration for two or more interconnected products to achieve best performance or specific functions Is a complement to other product specific documents Target groups installation service suppo
52. ter suited to voice Some of the components in WPA2 Enterprise are 802 1X TKIP and the AES based CCMP 802 1X specifies how authentication data is passed between a mobile device the AP and a RADIUS server TKIP and AES are protocols and algorithms that improves the security of keys The AES based CCMP is an encryption protocol used to provide data confidentiality origin authentication and replay protection An important element of the authentication process is the 4 way handshake method for exchanging cipher keys The key exchange is performed at every BSS transition roaming or 7 September 2011 Ver G 13 System Description Ascom VoWiFi System TD 92313EN handover The amount of time needed for the key exchange is implementation dependant and differs between AP manufacturers Like WPA WPA2 has a Pre Shared Key mode PSK WPA2 Personal designed for SOHO small office home office wireless networks that cannot afford the cost and complexity of an 802 1X authentication server Key Caching is another feature that was added to WPA2 This allows a mobile device to cache the master keys it gains through a successful authentication with an AP and re use it in a future association with the same AP This fast roaming technique is called pre authentication and it offers a way for the mobile device to pre authenticate with an AP before it needs to handover establishing a Pairwise Master Key PMK that can be cached for a period of time usu
53. y within the network it is important that APs are placed so that the micro cells overlap Fast hand over increases the performance Note APs are third party products 5 3 Controller Depending on network size and infrastructure Controllers can be used The Controller provides mobility security and RF services as an overlay on top of an existing LAN infrastructure Note Controllers are third party products 1 Requires some type of conference bridge in the system 2 Requires a Presence Management System 7 September 2011 Ver G 23 System Description Ascom VoWiFi System TD 92313EN 5 4 RADIUS Server RADIUS is an authentication server that centralize the authentication process It stores the user names and passwords that identify the clients allowed to log on to the system The authentication server may be a stand alone system or a software residing on for example the Controller Note RADIUS servers are third party products 5 5 Integrated Wireless Messaging and Services IMS3 IMS3 is a web based tool used for device management messaging and alarm handling It is a Unite module based on the ELISE3 hardware designed as an all in one solution for centralized management of portable devices Also it is an IP messaging gateway responsible for the alarm and message handling between the VoWiFi system and the Unite system Network Time Protocol NTP Open Access Protocol OAP Messaging Groups Device
54. ystem All messaging to and from the VoWiFi system goes through the Unite module IMS3 Unite CM Presence management is supported if a Presence Management system is connected for example Netwise Two types of location are supported either AP location which will give an approximate location of the VoWiFi Handset or a more accurate location of the VoWiFi Handset by using a third party location equipment together with Ascom Unite infrastructure components See Function Description Ascom VoWiFi System TD 92314EN for a description of the functions supplied by the Ascom VoWiFi system 7 September 2011 Ver G 27 System Description Ascom VoWiFi System TD 92313EN 7 1 System Solution When Connected to IP PBX Other Ascom Systems Messaging client 4 E P NoWiFi System C Other Unite mode Access Points LAN A ag um Q We x Location Server ES Presence li Management o System ae t E gt HENBNN IP PBX em PO Figure 13 Connection to other systems and to IP PBX 7 2 System Solution When Connected to Traditional PBX Other Ascom Systems Messaging client S wae NoWiFi System Sc Other Unite i modules Access Points an aye Y p Ti SX B bw CM IE Presence Management e System Main PBX M m ice e Figure 14 Co
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