Arian Durresi1Wireless MobileWireless MobileTelephonyTelephonyArian Arian DurresiDurresiCIS DepartmentCIS DepartmentThe Ohio State UniversityThe Ohio State UniversityColumbus, OH 43210Columbus, OH [email protected]@cis.ohio-state.edu http://www.cis.ohio-state.edu/~durresi/Arian Durresi2q Why wireless mobile telephony ?q First Generation, Analog technologiesq Second Generation, Digital :m D-AMPS, GSM, IS-95q Third Generation: ITU IMT-2000OverviewOverviewArian Durresi3Why Wireless Mobile Telephony ?Why Wireless Mobile Telephony ?q Negroponte Switch : Personal mobile communicationsgo on Ether, Broadcast communications on cableq Frequency Spectrum probably the most valuablenatural resourceq Progress in microelectronic - very smart mobileterminalsq More open for business opportunitiesq Mobile phone the only technology with a growth ratehigher than Internet. By the year 2003: 700 millionsInternet users and 830 millions mobile phone usersArian Durresi4Growth of Cellular MarketGrowth of Cellular MarketArian Durresi5Fixed & Mobile GrowthFixed & Mobile GrowthArian Durresi6Mobile Phone First GenerationMobile Phone First Generationq First Generation: Analog, 70’-80’, Access FDMAm Advanced Mobile Phone System (AMPS) 800MHz, North Americam Total Access Communication System (TACS) 900MHz, Europem Nordic Mobile Telephone (NMT) 450 and 900MHz, Sweden, Norway, Denmark, Finland etc.m Good basic service, good territorial coverage.m Continue to operate profitably. Will survive forsome timeArian Durresi7Mobile Phone Second GenerationMobile Phone Second Generation(2G)(2G)q The need for second generation:m Capacity. The old systems were almost saturatedm More services, specially value addedm Analog system more vulnerable to physicalinfluences and disturbancesArian Durresi8q Second Generation. Digital Technologym Global System for Mobile Communication (GSM),Europe +, in 120 countries (US too), 97.6 millionsubscribers, 200 networks, 33% of the world marketm Digital Advanced Mobile Phone System (D-AMPS):International Standard (IS-136), US +m Interim Standard 95 (IS-95): 13million subscribers, 50% of US market, Asia (South Korea), SouthAmerica.m Personal Digital Cellular (PDC): Japan, 33 millionsubscribersq Third Generation in development2G 2G contcont..Arian Durresi9Multiple Access SchemesMultiple Access SchemesFrequency FrequencyTimeTimeFrequencyTimech1 ch2 ch 3ch1ch2ch3ch1ch2ch3FDMA TDMA CDMAq Multiple access = Supporting more than onecommunication channel on a radio resourceq Big debate: Who will win TDMA or CDMA?Arian Durresi10TDMA TDMA vsvs. CDMA. CDMAq Spectrum Efficiency: Which multiple access schemehas better bps/Hz.cell ?q Flexibility: Which access scheme offers betterflexibility to handle multi-rate, -cell, -load, and -services ?q TDMA: some flexibility advantages, but has aspectrum efficiency disadvantageq CDMA: Less flexibility but has better spectrumefficiency Hasq Actual results depend on standards detailsArian Durresi11TDMATDMA vs vs. CDMA . CDMA contcont..q Answer unclearm IS-95 is probably superior to IS-54/136m IS-95 vs. GSM is unclearm IS-95 is clearly more complexq IS-54/136 is a grossly sub-optimum TDMA systemq GSM is a sub-optimum TDMA system (but prettygood)q IS-95 is a sub-optimum CDMA systemArian Durresi12Cellular SystemCellular SystemLarge cells for lowdensity traffic areasSmall cells for high densitytraffic areasq Cellular structure permits to reuse the frequencies and to distribute the resources depending on the trafficArian Durresi13Radio Resource ManagementRadio Resource Managementq Cell planning and management quasi online :m 1. Simulation of radio propagation using data fromsatellite about the territory, building, vegetation etc.m 2. Optimization of step 1: radio parameters, power.m 3. The dimensions of the cells and number ofchannels are calculated from the traffic foreseen inthat area.m 4. Frequency distribution among the cells, trying toreduce the interference.q Specialized personnel, computer system: OperationSupport Systems (OSS)Arian Durresi14IS-136IS-136q Telecommunication Industry Association TIAstandard IS-136, November 1994q IS-136 or D-AMPS is a superset of IS-54, which is adevelopment of AMPS (analog)q AMPS: Advanced Mobile Phone Systemq Access scheme: TDMAq Frequencies 800MHz, 1.9GHz, Channel bandwidth300KHzq D-AMPS worldwide network with over 13 millionsubscribers, analog + digital 75 millionq Voice is digitized at 8kbpsArian Durresi15IS-136 IS-136 contcont..q It is possible to upgrade easily from an analog AMPSnetwork to a digital D-AMPS networkq Digital and analog AMPS channels can co-exist in thesame networkq A dual handset can operate in both analog and digitalAMPS, in both 800 and 1900 MHz.q Asynchronous data service, fax, Short MessageService, Sleep Mode capabilityq Allow hierarchical cell structures to be implementedq D-AMPS offers CDPD serviceq New: IS-136HS High Speed extended data rate to384kbpsArian Durresi16GSMGSMq Global System for Mobile Communicationq 1982 CEPT, 1989 ETSI, standard 8000 pagesq GSM 900 MHz, DCS 1800 MHz, DCS 1900 MHz inUS and Canadaq Access scheme: TDMA /FDMAq Services: Telephony - digitized voice 13kbs, dataservices up to 9.6bps soon 38.4kbps, group 3facsimile, Short Message Service (SMS), ISDN, X.25q 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 Durresi17Architecture of the GSM networkArchitecture of the GSM networkMESIMBTSBTSBSCBSCMSCHLR VLREIR AuCPSTNUmAbisAq All the interfaces are standard - this permits a fierce competition among the vendors and a multi vendor network - advantage for the operatorsArian Durresi18Elements of GSM ArchitectureElements of GSM Architectureq SIM: Subscriber Identity Module contains the International Mobile Subscriber Identity (IMSI) usedto identify the subscriber to the system, a secret keyfor authenticationq ME: Mobile Equipmentq BTS: Base Transceiver Station handles the radio-linkprotocols with the Mobile Station.q BSC: Base Station Controller handles radio-channelsetup, frequency hopping, and handoversq HLR: Home Location Register - all the administrativeinformation of each subscriber, and the currentlocation of the mobileArian Durresi19Architecture of GSM networkArchitecture of GSM networkq VLR: Visitor Location Register contains selectedinformation, for call control and services for mobiles located in its geographic