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GSM

GSM. BY, Murali Iyengar +91 9894 3247 10. GSM. INTRODUCTION GSM FACTS GOALS OF GSM SERVICES & FEATURES SYSTEM ARCHITECTURE CHANNEL TYPES FRAME STRUCTURE SIGNAL PROCESSING. Murali Iyengar +91 9894 3247 10. INTRODUCTION.

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GSM

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  1. GSM BY, Murali Iyengar +91 9894 3247 10

  2. GSM • INTRODUCTION • GSM FACTS • GOALS OF GSM • SERVICES & FEATURES • SYSTEM ARCHITECTURE • CHANNEL TYPES • FRAME STRUCTURE • SIGNAL PROCESSING Murali Iyengar +91 9894 3247 10

  3. INTRODUCTION • GSM:- ESTI standard for 2G pan- European digital cellular with international roaming. • Developed to solve the fragmentation problem of first cellular system. • First introduced in European market in 1991. Murali Iyengar

  4. GSM FACTS - Used in over 170 countries - Over 400 GSM network operators - Over 550 million People Were subscribers to GSM TDMA pdk GSM 550 million CDMA 90 million Murali Iyengar

  5. GOALS OF GSM • Improved spectrum efficiency • High quality speech • International roaming • Low cost mobile set & base station • Support for new services • Compatibility with ISDN & other telephone company services Murali Iyengar

  6. SERVICES User services : # Telephone services - emergency calling & facsimile. # Bearer services or data services – packet switched protocols data rates from 300bps to 9.6kbps. # Supplementary ISDN services – call diversion , caller identification SMS Murali Iyengar

  7. FEATURES • SIM:-Memory device stores information( subscriber’s identification no. , networks , countries) • On air privacy :- made possible by encrypting the digital bit stream sent by GSM transmitter Murali Iyengar

  8. SYSTEMARCHITECTURE Consist of three major parts: # base transceiver station # base station controller # the transcoder & adaptation unit Murali Iyengar

  9. SYSTEM ARCHITECTURE HLR VLR AUC PSTN BSC MSC ISDN BSC DATA OMC NETWORK SWITCHING SUBSYSTEM PUBLIC NETWORK BASE STATION SUBSYSTEM

  10. BASE TRANSRECIVERSTATION • Serves a single cell • Usually placed in center of a cell • Coding • Crypting • Multiplexing • Modulating • synchronizing Murali Iyengar

  11. BASE STATION CONTROLLER BTS BSC • Translates the 13 kbps voice • Frequency hopping • Time and frequency • Power management • Time delay measurement To MSC 2 mbps Abis

  12. TRANSCODER & ADAPTATION UNIT • (13 kbps speech or data + 3 kbps additional synchronizing data) *4 = 64 kbps (TRAU) standard rate BSD 64 kbps TRAU MSC Murali Iyengar

  13. The various interfaces used in GSM MS BTS BTS BSC MSC PSTN MS SS7 BTS A interface (standardized) GSM radio air interface Abis interface Murali Iyengar

  14. FRAME STRUCTURE 6.12 SUPERFRAME 51 MULTIFRAME Murali Iyengar 120 MULTI FRAME 26 FRAME 4.615 8 TIME SLOTS FRAME 5 0 1 2 4 6 3 7 576.92 TM 1 3 57 1 26 57 3 8.25

  15. SIGNAL PROCESSING • Speech coding • Channel coding for data channels • Channel coding for control channels • Interleaving • Ciphering Murali Iyengar

  16. GSM operationsfrom speechinput to speech output Digitizing & source coding Source decoding Channelcoding Channel decoding SPEECH SPEECH interleaving De- interleaving Burstformatting Burst formatting ciphering De- ciphering Radio channel demodulation modulation

  17. CONCLUSION Murali Iyengar +91 9894 3247 10

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