Wireless Mobile TelephonyOverviewWhy Wireless Mobile Telephony ?Mobile Phone GenerationsGenerations (Cont)Generations (Cont)Multiple Access SchemesTDMA vs. CDMATDMA vs. CDMA cont.Slide 10Slide 11Slide 12IS-136 cont.GSMArchitecture of the GSM networkElements of GSM ArchitectureSlide 17GSM Signaling ProtocolsCall RoutingGSM featuresNew GSM featuresIS-95IS-95 (Cont)IS-95 contThird Generation Wireless TelephonyIUT IMT2000SummaryKey ReferencesReferences (Cont)Slide 30Arian Durresi1Wireless Mobile Wireless Mobile TelephonyTelephonyArian Durresi Arian Durresi 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 : D-AMPS, GSM, IS-95Third Generation: IUT IMT-2000OverviewOverviewArian Durresi3Why Wireless Mobile Why Wireless Mobile Telephony ?Telephony ?Negroponte Switch : Personal mobile communication on Ether.Frequency Spectrum the most probably valuable natural resourceProgress in microelectronic - very smart mobile terminalsMobile phone the only technology with a growth rate higher than Internet. By the year 2001 there will be more than 500 million Internet users and 600 millions mobile phone usersArian Durresi4Mobile Phone Mobile Phone GenerationsGenerationsFirst Generation: Analog, 70’-80’, Access FDMAAdvanced Mobile Phone System (AMPS) 800 MHz, North AmericaTotal Access Communication System (TACS) 900 MHz, EuropeNordic Mobile Telephone (NMT) 450 and 900 MHz, Sweden, Norway, Denmark, Finland etc. Good basic service, good territorial coverage.Continue to operate profitably. Will survive for some timeArian Durresi5Generations (Cont)Generations (Cont)The need for second generation:Capacity. The old systems were almost saturatedMore services, specially value addedAnalog system more vulnerable to physical influences and disturbancesArian Durresi6Generations (Cont)Generations (Cont)Second Generation. Digital Technology Global System for Mobile Communication (GSM), Europe +, in 120 countries (US too) , 82 million subscriber, 33% of the world market.Digital Advanced Mobile Phone System (D-AMPS): International Standard (IS-136), US +Interim Standard 95 (IS-95): US, Asia, South America. Personal Digital Cellular (PDC): Japan, 27 million subscribersThird Generation in developmentArian Durresi7Multiple Access SchemesMultiple Access SchemesFrequency FrequencyTimeTimeFrequencyTimech1 ch2 ch 3ch1ch2ch3ch1ch2ch3FDMA TDMA CDMAMultiple access = Supporting more than one communication channel on a radio resourceBig debate: Who will win TDMA or CDMA?Arian 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: Has some flexibility advantages, but has a spectrum efficiency disadvantageCDMA: Less flexibility but has better spectrum efficiencyActual results depend on standards detailsArian Durresi9TDMA vs. CDMA cont.TDMA vs. CDMA cont.Answer unclearIS-95 is probably superior to IS-54/136IS-95 vs. GSM is unclearIS-95 is clearly more complexIS-54/136 is a grossly sub-optimum TDMA systemGSM is a sub-optimum TDMA system (but pretty good)IS-95 is a sub-optimum CDMA systemArian Durresi10Cellular SystemCellular SystemLarge 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 trafficArian Durresi11Radio Resource ManagementRadio Resource ManagementCell planning and management quasi online :1. Simulation of radio propagation using data from satellite about the territory, building, vegetation etc.2. Optimization of step 1: radio parameters, power. 3. The dimensions of the cells and number of channels are calculated from the traffic foreseen in that area.4. Frequency distribution among the cells, trying to reduce the interference.Arian Durresi12IS-136IS-136Telecommunication Industry Association TIA standard IS-136, November 1994IS-136 or D-AMPS is a superset of IS-54, which is a development of AMPS (analog)AMPS: Advanced Mobile Phone SystemAccess scheme: TDMAFrequencies 800MHz, 1.9GHz, Channel bandwidth 300KHzD-AMPS worldwide network with over 12 million subscribers, analog + digital 72 million Voice is digitized at 8kbpsArian Durresi13IS-136 cont.IS-136 cont.It is possible to upgrade easily from an analog AMPS network to a digital D-AMPS networkDigital and analog AMPS channels can co-exist in the same networkA dual handset can operate in both analog and digital AMPS, in both 800 and 1900 MHz.Asynchronous data service, fax, Short Message Service, Sleep Mode capabilityAllow hierarchical cell structures to be implementedD-AMPS offers CDPD serviceArian Durresi14GSMGSM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 Durresi15Architecture 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 networkArian Durresi16Elements 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 Durresi17Architecture of the GSM networkArchitecture of the GSM