GSM原理介绍(英文)

1、 NOKIA nokia.ppt/1 / 11/28/2021. GSM900/DCS1800 . The GSM Network & Air Interface . Technical Basics . Speech Coding . Types of Channel . Making a Phone Call NOKIA nokia.ppt/2 / 11/28/2021Global System for Mobile( Groupe Special Mobile ) NOKIA nokia.ppt/3 / 11/28/20211982 Groupe Special Mobile?i

2、s created within CEPT1986 A Permanent Nucleus is set up1987 Main radio transmission techniques 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

3、 operators begin commercial operator NOKIA nokia.ppt/4 / 11/28/2021 Speech Services Data Services Short Message Services (SMS) Supplementary Services Subscriber Identity Module (SIM) Security Function NOKIA nokia.ppt/5 / 11/28/2021 TDMA 0.3GMSK Modulation Burst Power Transmission Neighbour Cells Mea

4、surement Hopping Uplink / Downlink DTx BER & Receiver Testing NOKIA nokia.ppt/6 / 11/28/2021GSM900GSM900DCS1800DCS1800PCS1900Uplink890 to880 to1710 to1710 to1850 to915MHz915MHz1785MHz1785MHz1910MHzDownlink935 to925 to1805 to1805 to1930 to960MHz960MHz1880MHz1880MHz1990MHzARFCN range1 to 1240 to 1

5、24 and512 to 885512 to 885512 to 810975 to 1023TX/RX Spacing45MHz45MHz95MHz95MHz80MHz(Freq.)TX/RX Spacing3 Timeslots(Time)Modulation Data 270.833kbit/sRateFrame Period4.615msTimeslot Period576.9usBit Period3.692usModulation0.3GMSKChannel Spacing200KHzTDMA Mux8MS Max Power20W( 8W is 8W8W1W1Wmax in us

6、e)MS Min Power13dBm5dBm4dBm0dBm0dBmMS Power 5 to 190 to 150 to 1530,31,0 to 15Control StepsVoice Coder Bit13kbit/s13kbit/s13kbit/s13kbit/s13kbit/sRate6.5kbit/s6.5kbit/s NOKIA nokia.ppt/7 / 11/28/2021 890 - 915 MHz Uplink / MS Transmit 935 - 960 MHz Downlink / BS Transmit Duplex Offset 45 MHz Channel

7、 Spacing 200kHz Channel numbering 1 - 124 Transmission Speed 270 Kbits NOKIA nokia.ppt/8 / 11/28/2021 1710 - 1785 MHz Uplink / MS Transmit 1805 - 1880 MHz Downlink / BS Transmit Duplex Offset 95 MHz Channel Spacing 200kHz Channel numbering 512 - 885 Transmission Speed 270 Kbits NOKIA nokia.ppt/9 / 1

8、1/28/2021890900910920930940950960Freq45 MHzUplink ( Mobile to Base )Downlink ( Base to Mobile ) NOKIA nokia.ppt/10 / 11/28/20211710 1735 1760 1785 1800 1825 1850 1875Freq95 MHzUplink ( Mobile to Base )Downlink ( Base to Mobile ) NOKIA nokia.ppt/11 / 11/28/2021890.2890.4890.6890.8FreqGSM band200 kHz

9、NOKIA nokia.ppt/12 / 11/28/20211710.21710.41710.61710.8FreqDCS1800 band200 kHz NOKIA nokia.ppt/13 / 11/28/2021BSCBTSBTSBTSBSSBSCBTSBTSBTSBSSMSCMSCOMCOMCADCNMCVLRVLRHLRAUCEIRInterface to other networkMS NOKIA nokia.ppt/14 / 11/28/2021Terminology:MS- Mobile Station (移动台移动台)BSS- Base Station System (基站

10、系统基站系统)BTS- Base 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 Registe

11、r (归属位置寄存器归属位置寄存器)VLR- Visitors 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) NOKIA nokia.ppt/15 / 11/28/2021MSCBSCBSCBSCPSTNBTSBTSBTSAir InterfaceAbis InterfaceSS#7SS#7MS NOKIA nokia.ppt/16 / 11/28/20211100 1 011001 0PSKGuassian FilterSpectrum 200kHz NOKIA noki

12、a.ppt/17 / 11/28/2021FcFc + 67.708KHzFc + 67.708KHz+67.708KHz-67.708KHzData Type ?0Data Type ?1 NOKIA nokia.ppt/18 / 11/28/2021401234567123456FrequencyAmplitudeARFCNTimeslotPhysical Channel isan ARFCN and Timeslot NOKIA nokia.ppt/19 / 11/28/2021Terminology:FDMA - Frequency Division Multiple AccessTD

13、MA - Time Division Multiple AccessARFCN - Absolute RF Channel NumberTS - TimeslotPhysical - The Combination of a TS number Channels and ARFCN.Logical - Are Mapped on Physical Channels Channels NOKIA nokia.ppt/20 / 11/28/202110us10us10us10us8us8us3311575726 148 Active Bits, 546.42us 147 Useful Bits54

14、2.8us-70dB-30dB-6dB+4dB-6dB-30dB-70dBTol -1.0dBTol +1.0dB NOKIA nokia.ppt/21 / 11/28/2021542.8 us / 147 Bits1081010810TimePower-700dBUpper LimitLower LimitActualusNormal Burst NOKIA nokia.ppt/22 / 11/28/2021321.23 us / 87 Bits 10 81010810TimePower-700dBUpper LimitLower LimitActualusAccess Burst87 bi

15、ts NOKIA nokia.ppt/23 / 11/28/2021Downlink / MS Receive5670123456701342067012345671342Uplink / MS Transmit5 NOKIA nokia.ppt/24 / 11/28/2021ARFCN0247360135061472531 264 572460357132104 5 6 7 01 23 4 5 6 7 00 34 5 67 0 1 2 3 4 51ARFCNUPLINKDOWNLINK45MHz. Uplink Lags Downlink by 3 Timeslot periods. Upl

16、ink and Downlink use same Timeslot Number. Uplink and Downlink use same Channel Number (ARFCN). Uplink and Downlink use different bands(45MHz apart for GSM900) NOKIA nokia.ppt/25 / 11/28/2021MODCouplerSwitchSynthRegisterControlUplink BS 1BS 2MonitoringRX LevRX QualDownlink 165124165124Home BS NOKIA

17、nokia.ppt/26 / 11/28/202120ms 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 BitsImportant BitsOther Bits NO

18、KIA nokia.ppt/27 / 11/28/2021Type 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 BitsOut NOKIA nokia.ppt/28 / 11/28/2021456 Bits from 20ms

19、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

20、120msThere are 2 spare frames厖厖 One SACCH, one Idle NOKIA nokia.ppt/29 / 11/28/2021ChannelcodingSpeechDigitizing and Source codingInterleavingBurst formatting CipheringModulationChanneldecodingSpeechSource decodingDe-interleavingBurst formatting DecipheringDemodulation NOKIA nokia.ppt/30 / 11/28/202

21、1MS Turn OnMS searches 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

22、 request serviceUsing SACCH - adjust power, TA & report RX QualetcMS goes to the assigned SDCCH ( Freq., timeslot, . )for authentication + location UpdateMS sendsRACHBS assigns SDCCH to MS using the CCCH NOKIA nokia.ppt/31 / 11/28/2021BS pages MS usingthe CCCH MS sends RACHBS ORIGINATED CALLMS O

23、RIGINATED CALLMS responds withRACH BS assigns MS to SDCCH or TCHMS transmits 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 on TCH, MSreports power + Rx quality , BScommands MS to adjust power ,TADuring in