1.GSM basic.ppt

1、安捷倫科技股份有限公司 儀器系統(tǒng)工程部 應(yīng)用工程師,桃園縣平鎮(zhèn)市高雙路20號 電話:886-3-4959150 傳真:886-3-4929668 E-mail:rita-th_,Rita Wang 王 廷 華,Agenda,GSM Basic GSM Network & Air interface, Types of Channel, Speech Coding GSM Measurement Basic Mobile Block diagram & related information Shopboy E6392A Operation Training Overview & Operati

2、on,Agenda,GSM Basic Lesson Overview & GSM Snapshot GSM Network & Air interface Types of Channel Speech Coding Review Quiz,GSM,Lesson Overview,In this lesson you will learn some of the concepts and implementations of the GSM network.,Lesson Objectives,Identify the structures used in digital networks.

3、 These include: Cells Sectors Base Stations.,Lesson Objectives,Identify the elements used in GSM networks. These include: Base Transceiver Station Base Station Controller Mobile Switching Center.,Lesson Objectives,Identify how the GSM system communicates over the air-interface.,Lesson Objectives,Rec

4、ognize the different parts of a system that manipulate the analog voice so that it can be transmitted over the air interface.,GSM History,1981 analogue cellular introduced Franco-German study of digital pan-european cellular system 1982 Groupe Spcial Mobile (GSM) formed within CEPT 1986 Permanent gr

5、oup to create standards for a digital system 1987 MoU signed by over 18 countries 1989 GSM was moved into the ETSI organisation GSM name changed to Global System for Mobile communications. The committees working on the system changed from GSM to SMG 1990 DCS1800 (edited GSM900) specification develop

6、ed 1992 Australia was the first non-European country to join the MoU,GSM Around the World,Queenferry Microwave Division,USA: PCS1900,UK: GSM900 DCS1800,Thailand: DCS1800,Canada: PCS 1900,Argentina, Brazil, Chile: DCS 1800,Malaysia: DCS 1800,CIS, Denmark, Finland, France, Germany, Greece, Hungary, Po

7、land, Norway, Sweden, Switzerland: GSM900 DCS 1800,Singapore: DCS1800,Hong Kong: PCS 1900,GSM Network,NMC,OSI,Interface to other networks,MS,MS,BTS,BTS,BTS,BSS,BSS,MSC,MSC,VLR,VLR,HLR,EIR,AUC,OMC,OMC,BSC,GSM Network Interfaces,PSTN,SS#7,SS#7,LAP-D,LAP-Dm,Abis Interface,Rf Test Equipment,Um Interface

8、,Protocol Analyzers,Protocol Analyzers,Protocol Analyzers,GSM Air Interface,Separate Bands for Uplink and Downlink TDMA and FDMA Multiplex 124 Frequency Channels (ARFCN) for GSM900 200kHz Channels 8 Mobiles share ARFCN by TDMA 0.3 GMSK Modulation 270.833 kbits/sec. rate Variable Tx Power and Timing.

9、,GSM Bands,Downlink,Uplink,GSM Cell Plan,GSM Omni Cell,Cell,Omnidirectional Antenna,GSM Sectored Cell,Sector,Sectored Antenna,Cell,GSM Broadcast Channel,BCH 1,BCH 3,BCH 2,GSM Traffic Channel,BCH,TCH,GSM Hand-Off,BCH,TCH,Mobile constantly monitors received TCH quality (RxQual & RxLev),GSM FDMA and TD

10、MA,1 2 3 4 5 6,ARFCN #,Frequency,Amplitude,Time,0,1,2,3,4,5,6,7,Timeslot #,GSM Burst,Frequency,Amplitude,Time,Overshoot,Lobes due to modulation,Raised lobes due to ramp up,GSM Burst - TDMA,Amplitude,Time,148 Bits in the Useful Part of the Burst,3 57 1 26 1 57 3,GSM Burst - Data Structure,Tail Bits,D

11、ata Bits,Stealing Flag,Midamble Bits,Stealing Flag,Data Bits,Tail Bits,GSM TDMA Power Burst,Downlink and Uplink,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 a

12、part for GSM900),Measuring Adjacent Cell BCH Power,Hopping Traffic Channel,GSM Time Delay,BTS,Cell radius 35 km,Signal travel or time 117 usec,GSM Time Delay,Ideal,Delayed,GSM Midamble Equalisation,Reference Color Code (Midamble),Actual Received Signal,GSM Power Steps,Too much Power Low Talk Time,To

13、o little Power Dropped Calls,Adjusted according to Received Signal Strength and Quality at MS,GSM RACH,Random Access Channel Used by the mobile to get attention Mobile doesnt know path delay So RACH has to be a special SHORT BURST Mobile sends normal burst after getting Timing Advance,GSM BCH,Broadc

14、ast Channel One BCH on all the time, in every cell BCH Information carried in Timeslot 0 other Timeslots can be used for TCH or filled with dummy data Allows Mobile to Synchronise Identifies Network Carries Paging and other Control Information,GSM SACCH,Slow Associated Control Channel DOWNLINK Mobil

15、e Tx Power Commands Mobile Timing Advance Cells Channel Configuration UPLINK Received signal quality report (RXQual) Received signal level report (RXLev) Adjacent BCH power measurements Mobiles status,GSM FACCH,Fast Associated Control Channel Used by BS and MS to send large amounts of data FAST Rapi

16、d message exchange for hand-offs Control Bits are either side of midamble: Indicate if TCH or FACCH,GSM SDCCH,Stand Alone Dedicated Control Channel Used during Call Setup Stepping Stone between BCH and TCH Used for Authentication Etc.,GSM Voice Path,Codec,Interleave,Vocoder,Modulate,Burst,GSM Vocode

17、r,20ms Speech makes 260 Bits Output 13 kbit/s 3 Classes of bits output,RELP - Residually Excited Linear Predictive LTP - Long Term Predictive,Vocoder,GSM Vocoder(Cont.),GSM Codec,CODEC,13 kbit/s,456 bits,13 kbit/s,260 bits,3 classes of bits are error corrected in different ways Class 1a bits:Error C

18、orrection and CRC bits added Class 1b bits:Error Correction only Class ll bits:No Error Correction,GSM Codec(Cont.),GSM Interleave,Interleave,456 bits,456 bits,13 kbit/s,456 bits,13 kbit/s,456 bits,GSM Modulate,Output 270.833 kbits/s 0.3GMSK (continuous),Input 13 kbits/s (Error Corrected Interleaved

19、),Modulate,GSM Burst,Burst,270.833 kbits/s Output 0.3GMSK (bursted),Input 270.833 kbits/s 0.3GMSK (continuous),SIMSubscriber ID Module,Lesson Review,Lesson Review,Be able to recognize the key system elements and understand their role in the network as a whole.,Lesson Review,Important terms to rememb

20、er are Base Station System (BSS) Base Transceiver Station (BTS) Base Station Controller (BSC) Mobile Switching Center (MSC).,Lesson Review,Understand how mobile phones can move around a network, even into other networks, and be able to provide the user with seamless coverage.,Lesson Review,Important

21、 terms to remember are Home Location Register (HLR) Visitors Location Register (VLR) Authentication Center (AUC).,Lesson Review,Understand the roles that channels play in a network. You should be able to recognize the different channels along with their functionality.,Lesson Review,GSM Broadcast Channel (BCH) Traffic Channel (TCH) Slow Associated Control Channel (SACCH) Fast Associated Control Channel (FACCH).,Lesson Review,Have a bas