【网络工程】Nokia-GSM原理介绍.pptx

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1、Agenda.GSM900/DCS1800 .The GSM Network&Air Interface .Technical Basics .Speech Coding .Types of Channel .Making a Phone Call Global System for Mobile(Groupe Special Mobile)G S M1982 Groupe Special Mobile?is created within CEPT1986 A Permanent Nucleus is set up1987 Main radio transmission techniques

2、are chosen,based on prototype evalution(1986)1989 GSM becomes an ETSI technical committe1990 The phase 1 GSM 900 specifications are finalized1991 First systems are running 1992 All major European GSM 900 operators begin commercial operator GSM Development History Speech Services Data Services Short

3、Message Services(SMS)Supplementary Services Subscriber Identity Module(SIM)Security FunctionGSM/DCS1800 FunctionalitiesRF AspectsTDMA0.3GMSK ModulationBurst Power TransmissionNeighbour Cells MeasurementHoppingUplink/Downlink DTxBER&Receiver Testing GSM900/DCS1800/PCS1900GSM Frequency Range890-915 MH

4、z Uplink/MS Transmit935-960 MHz Downlink/BS TransmitDuplex Offset 45 MHzChannel Spacing 200kHzChannel numbering 1-124Transmission Speed 270 Kbits DCS1800 Frequency Range1710-1785 MHz Uplink/MS Transmit1805-1880 MHz Downlink/BS TransmitDuplex Offset 95 MHzChannel Spacing 200kHzChannel numbering 512-8

5、85Transmission Speed 270 Kbits GSM Primary Band890900910920930940950960Freq45 MHzUplink(Mobile to Base)Downlink(Base to Mobile)DCS1800 Primary Band1710 1735 1760 1785 1800 1825 1850 1875Freq95 MHzUplink(Mobile to Base)Downlink(Base to Mobile)Carriers at the border of the GSM band890.2890.4890.6890.8

6、FreqGSM band200 kHzCarriers at the border of the DCS1800 band1710.21710.41710.61710.8FreqDCS1800 band200 kHzGSM NetworksBSCBTSBTSBTSBSSBSCBTSBTSBTSBSSMSCMSCOMCOMCADCNMCVLRVLRHLRAUCEIRInterface to other networkMSGSM NetworksTerminology:MS-Mobile Station(移动台移动台)BSS-Base Station System(基站系统基站系统)BTS-Bas

7、e Transceiver Station(基站收发台基站收发台)BSC-Base Station Controller(基站控制器基站控制器)MSC-Mobile Switching Centre(移动业务交换中心移动业务交换中心)OMC-Operations and Maintenance Centre (操作与维护中心操作与维护中心)NMC-Network Management Centre(网络管理中心网络管理中心)AUC-Authentication Centre(鉴权中心鉴权中心)HLR-Home Location Register(归属位置寄存器归属位置寄存器)VLR-Visit

8、ors Location Register (来访位置寄存器来访位置寄存器)EIR-Equipment Identity Register(设备标识寄存器设备标识寄存器)MSCBSCBSCBSCPSTNBTSBTSBTSAir InterfaceAbis InterfaceSS#7SS#7GSM InterfaceMSGMSK Modulation1100 1 011001 0PSKGuassian FilterSpectrum 200kHzFcFc+67.708KHzFc+67.708KHz+67.708KHz-67.708KHzData Type?0Data Type?1Modulatio

9、n401234567123456FrequencyAmplitudeARFCNTimeslotPhysical Channel isan ARFCN and TimeslotTDMA and FDMATDMA and FDMATerminology:FDMA -Frequency Division Multiple AccessTDMA -Time Division Multiple AccessARFCN -Absolute RF Channel NumberTS -TimeslotPhysical -The Combination of a TS number Channels and A

10、RFCN.Logical -Are Mapped on Physical Channels Channels10us10us10us10us8us8us3311575726 148 Active Bits,546.42us 147 Useful Bits542.8us-70dB-30dB-6dB+4dB-6dB-30dB-70dBTol-1.0dBTol+1.0dBGSM TDMA Power BurstPower Time Template542.8 us/147 Bits1081010810TimePower-700dBUpper LimitLower LimitActualusNorma

11、l BurstPower Time Template321.23 us/87 Bits 10 81010810TimePower-700dBUpper LimitLower LimitActualusAccess Burst87 bitsUplink&DownlinkDownlink/MS Receive5670123456701342067012345671342Uplink/MS Transmit5Uplink&DownlinkARFCN0247360135061472531 264 572460357132104 5 6 7 01 23 4 5 6 7 00 34 5 67 0 1 2

12、3 4 51ARFCNUPLINKDOWNLINK45MHz.Uplink Lags Downlink by 3 Timeslot periods.Uplink and Downlink use same Timeslot Number.Uplink and Downlink use same Channel Number(ARFCN).Uplink and Downlink use different bands(45MHz apart for GSM900)Frequency HoppingMODCouplerSwitchSynthRegisterControlUplink BS 1BS

13、2MonitoringRX LevRX QualDownlink 165124165124Home BS20ms BlocksSpeech CoderBits Ordered260 Bits260 Bits5013278.RELP and LTP Coder RELP-Residual-Excited Linear Prediction Coder LTP-Long Term Prediction.Converts Speech to Low Data Rate.20ms Speech makes 260Bits.Output 13kbit/sVery Important BitsImport

14、ant BitsOther BitsSpeech CoderError CorrectionType Ia 50Type Ib 132Type II 7850132783Type IaCRCType IbType IIBlock Code256625663478Re-ordering37878Half rate convolutional code456 Bits from 20ms of SpeechType IaType IbType IbType IaTailType IICRC262 BitsIn456 BitsOutDiagonal Interleaving456 Bits from

15、 20ms of Speech456 Bits from 20ms of Speech575757575757575757575757575757575757 5757 5757 5757 575757 5757 57TCHTraffic Channel(TCH)Bursts Carry Two 57 Bits Blocks(114)Each120ms of Speech=456x6=2736 bits2736/114=24 bursts I.e.24frames(mobile transmits once per frame)Multiframe has 26 frames in 120ms

16、There are 2 spare frames厖厖 One SACCH,one IdleSpeech to Radio/Radio to SpeechChannelcodingSpeechDigitizing and Source codingInterleavingBurst formatting CipheringModulationChanneldecodingSpeechSource decodingDe-interleavingBurst formatting DecipheringDemodulationMS Camp on Flow ChartMS Turn OnMS sear

17、ches channelsand orders by signalstrengthMSStongestBCCHFCCH on BCCH and adjusts timebaseSCH on BCCH and fine tunes timebase&timingDecode BCCH&store info Is BCCHin PLMN?MSNext StongestBCCHYESNOYESNONOLocation=Previous Location?YESYESMS camped on-listens for page,can request serviceUsing SACCH-adjust

18、power,TA&report RX QualetcMS goes to the assigned SDCCH(Freq.,timeslot,.)for authentication+location UpdateMS sendsRACHBS assigns SDCCH to MS using the CCCH Orignated CallBS pages MS usingthe CCCH MS sends RACHBS ORIGINATED CALLMS ORIGINATED CALLMS responds withRACH BS assigns MS to SDCCH or TCHMS t

19、ransmits and receives speech on TCHTCHUsing the FACCH onTCH authentication&location updateUsing the SDCCH,authentication,call setup,and TCH assignmentUsing the SACCH,BS commands MS to adust power+timing,MSreports power+Rx quality of BCCH+adjacent BCCHMS transmits+receives speechon TCHUsing the SACCH

20、 on TCH,MSreports power+Rx quality,BScommands MS to adjust power,TADuring inactive timeslots,MS measures adjacent cells,BCCHCall disconnected by MS or BSSubscriber Identity Module(SIM)Subscriber Identity Module(SIM)SIM contains(at least)following information:IMSI (International Mobile Subscriber Ide

21、ntification)MCC&MNC (Mobile Country Code and mobile Network Code)Any other user specific informationInternational Mobile Subscriber Identity(IMSI)International Mobile Subscriber Identity(IMSI)IMSI=MCC+MNC+MSINNMSI3 digits2 digitsNot more than 15 digitsIMSI=International Mobile Subscriber IdentityMCC

22、=Mobile Country CodeMNC=Mobile Network CodeMSIN=Mobile Station Identification NumberNMSI=National Mobile Subscriber IdentityInternational Mobile Equipment Identity(IMEI)International Mobile Equipment Identity(IMEI)IMEI=International Mobile Equipment IdentityTAC=Type Approval CodeFAC=Final Assembly CodeSNR=Serial NumberSP=SpareIMEI=TAC+FAC+SNRSP+6 digits2 digits6 digits1digit