Wireless Mobile TelephonyOverviewWhy Wireless Mobile Telephony ?Growth of Cellular MarketMobile + InternetMobile phone: Three Generations2GTDMA vs. CDMASlide 9GSMArchitecture of the GSM networkElements of GSM ArchitectureArchitecture of GSM networkCall RoutingGSM featuresGSM EvolutionGSM/GPRS ArchitectureSlide 18IS-136 cont.IS-136 Evolution to 3GIS-95IS-95 (cont.)IS-95 EvolutionThird Generation (3G)Slide 25ITU International Mobile Telecommunication (IMT) 20003G: Mobile InternetSummaryKey ReferencesReferences (Cont)Arian Durresi1Wireless Mobile Wireless Mobile TelephonyTelephonyDr. Arian DurresiDr. Arian DurresiCIS Department CIS Department The Ohio State UniversityThe Ohio State UniversityColumbus, OH 43210Columbus, OH [email protected]@cse.ohio-state.edu http://www.cse.ohio-state.edu/~durresi/Arian Durresi2Why wireless mobile telephony ? First Generation, Analog technologiesSecond Generation, Digital : GSM, D-AMPS, IS-95Third Generation: ITU IMT-2000IMT-2000 also as Internet Mobile TelecommunicationOverviewOverviewArian Durresi3Why Wireless Mobile Telephony ?Why Wireless Mobile Telephony ?Negroponte Switch : Personal mobile communications go on Ether, Broadcast communications on cableFrequency Spectrum probably the most valuable natural resourceProgress in microelectronic - very smart mobile terminalsMore open for business opportunitiesMobile phone the only technology with a growth rate higher than Internet. By the year 2003: 700 millions Internet users and 830 millions mobile phone usersArian Durresi4Growth of Cellular Market Growth of Cellular Market FixedArian Durresi5Mobile + InternetMobile + Internet[IPWRLSS]Arian Durresi6Mobile phone: Three GenerationsMobile phone: Three GenerationsFirst Generation: Analog, 70’-80’, Access FDMAGood basic service, good territorial coverage.Continue to operate profitably. Will survive for some timeSecond Generation, Digital TechnologyCapacity: The old systems were almost saturatedMore services, specially value addedAnalog system more vulnerable to physical influences and disturbancesThird Generation in development: 2G will seamlessly evolve to provide high-speed data and support for multimedia applicationArian Durresi72G2GStandardSubscribersCountries/Monthly grow Millions Networks MillionsGSM 183.3 120/284 7.6PDC 42.3 1/30. 0.6IS-136 24.3 34/104 1.4IS-95 31.5 12/31. 1.5[3GSTD] Digital Cellular Standards, End of June 1999•Global System for Mobile Communication (GSM), Europe +, US •Digital Advanced Mobile Phone System (D-AMPS): International Standard (IS-136), US + •Interim Standard 95 (IS-95): 50% of US market, Asia (South Korea), South America. •Personal Digital Cellular (PDC): JapanArian Durresi8TDMA vs. CDMATDMA vs. CDMASpectrum Efficiency: Which multiple access scheme has better bps/Hz.cell ?Flexibility: Which access scheme offers better flexibility to handle multi-rate, -cell, -load, and -services ?TDMA: some flexibility advantages, but has a spectrum efficiency disadvantageCDMA: Less flexibility but has better spectrum efficiency Has Actual results depend on standards detailsArian Durresi9Cellular System Cellular System Large cells for low density traffic areas Small cells for high density traffic areasCellular structure permits to reuse the frequencies and to distribute the resources depending on the trafficCell planning and management considers radio propagation over the territory done by Operation Support Systems (OSS) [IRMA]Arian Durresi10GSMGSMGlobal System for Mobile Communication1982 CEPT, 1989 ETSI, standard 8000 pagesGSM 900 MHz, DCS 1800 MHz, DCS 1900 MHz in US and Canada Access scheme: TDMA /FDMAServices: Telephony - digitized voice 13kbs, data services up to 9.6bps soon 38.4kbps, group 3 facsimile, Short Message Service (SMS), ISDN, X.25International roaming: Subscribers can use the same phone terminal around the world and bill to home. This is a very attractive feature for the users.Arian Durresi11Architecture of the GSM networkArchitecture of the GSM networkMESIMBTSBTSBSCBSCMSCHLR VLREIR AuCPSTNUmAbisAAll the interfaces are standard - this permits a fierce competition among the vendors and a multi vendor network - advantage for the operatorsArian Durresi12Elements of GSM ArchitectureElements of GSM ArchitectureSIM: Subscriber Identity Module contains the International Mobile Subscriber Identity (IMSI) used to identify the subscriber to the system, a secret key for authenticationME: Mobile EquipmentBTS: Base Transceiver Station handles the radio-link protocols with the Mobile Station.BSC: Base Station Controller handles radio-channel setup, frequency hopping, and handoversHLR: Home Location Register - all the administrative information of each subscriber, and the current location of the mobileArian Durresi13Architecture of GSM networkArchitecture of GSM networkVLR: Visitor Location Register contains selected information, for call control and services for mobiles located in its geographic area.MSC: Mobile services Switching Center - normal switching node of the PSTN (Public Switched Telephone Network), plus functionality for registration, authentication, location updating, handovers, and call routing to a roaming subscriber.EIR: Equipment Identity RegisterAuC: Authentication Center stores a copy of the secret key of each subscriber's SIM card, used for authentication and encryptionArian Durresi14Call RoutingCall RoutingMSISDN: Mobile Subscriber ISDNIMSI: International Mobile Subscriber Identity MSRN: Mobile Station Roaming NumberTIMSI: Temporary IMSI is used in the air to protect the real identity-IMSIPTSN SwitchMSC GatewayHLRMSC/VLR MSFixed SubscriberMSISDNMSISDNMSISDNIMSIMSRNMSRNMSRNTIMSIMSRNArian Durresi15GSM featuresGSM features124 channel of 200kHz, each channel up to eight logic channels: Traffic (TCH) voice/data, Control (CCH) control and signaling, Cell Broadcast (CBCH) Up to eight traffic channels TCH per frequencyMultipath equalization. The system “studies” the radio channel using a known sequence in every data time slot, than “reacts” constructing an inverse filter.Frequency hopping helps to reduce interferenceAutomatic Power Control reduces co-channel interferenceHigh Speed Circuit Switched Data (HSCSD): Using eight time slots get a transmission rate of 76.8 kbpsArian