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The Wireless Communication System

The Wireless Communication System. Xihan Lu. Wireless Communication. Cellular phone system Cordless telephone system Bluetooth Infrared communication Microwave communication IEEE Wireless LANs (Wi-Fi) Satellite communication. Why “ Cellular ” ?. Three Generations. AMPS NMT TACS

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The Wireless Communication System

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  1. The Wireless Communication System Xihan Lu

  2. Wireless Communication • Cellular phone system • Cordless telephone system • Bluetooth • Infrared communication • Microwave communication • IEEE Wireless LANs (Wi-Fi) • Satellite communication

  3. Why “Cellular”?

  4. Three Generations AMPS NMT TACS HCMTS GSM GPRS WCDMA CDMA2000 TD SCDMA 1G 2G 3G

  5. 1G • Start early 80’s • Analogue technique • AMPT (Advanced Mobile Phone System): North America • NMT (Nordic Mobile Telephony):North Europe • TACS (Total Access Communication Service):Europe, China • HCMTS (High Capacity Mobile Telephone System):Japan

  6. FDMA • Frequency Division Multiple Access • Different carrier frequencies are assigned to different traffic channels(speech) • One carrier frequency can only carry one single speech channel at one time

  7. FDMA

  8. Shortage • Voice information only • Unsafe （eavesdropping） • Waste of frequency resource

  9. 2G • Start early 90’s • Digital technique • GSM : Global System of Mobilephone • GPRS : General Packet Radio Service • D-AMPS : Digital AMPS

  10. GSM • TD/FDMA: A mix of FDMA and TDMA • The whole useable spectrum was divided to many 200k Hz carrier frequencies —FD • Each carrier was divided into 8 timeslots (burst) —TD • Each burst is assigned to a user(a logical traffic channel) • One carrier frequency can carry up to 8 logical traffic channels (voice or data) at the same time • The maximum data communication rate is 14.4 kbps

  11. FD / TDMA

  12. Network Structure

  13. BTS,BSC and MSC • BTS & BSC: Base Transceiver System and Base Station Controller. Radio signal transceiver, a connection between handset and MSC • MSC: Mobile services Switching Center, switching center of the GSM network, and connect to other networks

  14. Databases • HLR : Home Location Register, contains static information of subscribers and location update data • VLR : Visitor Location Register, embedded in MSC to avoid delay, contains current location information of handsets • AUC : Authentication Center, stores secret keys for authentication and encryption of the radio channel • EIR : Equipment Identity Register, contains a list of all valid mobile equipment in the network, by its International Mobile Equipment Identity (IMEI)

  15. GPRS • Upgrade of existed GSM network • Improves the data communication ability

  16. GPRS

  17. Network nodes • GGSN: Gateway GSM Support Node, • Protocol transferring, data encapsulation, a connection to external networks • SGSN: Service GSM Support Node, • Communicate with HLR and mobile handsets, authorization and admission control, charging, mobility management

  18. Data communications • In GSM, one user occupies one traffic channel to exchange voice/data information • In GPRS, up to 8 traffic channels(a whole carrier) can be dynamically combined together for one data communication application • The theoretically maximum data transmission rate: 14.4k bps * 8 = 115.2k bps

  19. Advantages of GPRS • Higher data rate • Seamless connection to internet • Packet switching rather than circuit switch, bandwidth is only used when the data is actually used, even though it is always connected • A primary step to 3G

  20. shortage • Not fast enough for the multimedia service • The data rate falls when the network is busy • Upgrade of handset

  21. 3G

  22. 3G-Standards • Three CDMA standards approved by ITU: • Direct Spread CDMA(WCDMA) : Europe, Japan • Multi-Carrier CDMA(CDMA 2000) : North America • TD-Synchronous CDMA(CDMA TDD) : Europe, China

  23. 3G-CDMA • Code Division Multi Address • Spread spectrum technology • Each single traffic channel occupies the whole spectrum, but distinguished by a unique digital code • Walsh code: an orthogonal 64 bit pattern, unique in the network

  24. CDMA

  25. Features • Better voice quality • Up to 2 Mbps data communication rate • Increase battery life • Soft hand-off • Excellent data safety • More effective spectrum usage than 2G

  26. Conclusion

  27. Conclusion

  28. References • www.gsmworld.com/technology/gprs/index.html • www.3gsmamericas.com/pdfs/EOF_Cannes_2003/Nortel_David_Smith.pdf • http://www.fcc.gov/Bureaus/Wireless/Reports/fcc98091.pdf • www.rogers.com • http://www.itu.int/ITU-D/ict/publications/wtdr_99/material/glossary.html • www.itu.int/home/imt.html • http://www.boeschatt.at/Mobil/mobilfunk_html.php?gsm_netzarchitektur.php • http://www.pt.com/products/gsmintro.html

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