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Cellular Networks

Cellular Networks. 1200. 1000. GSM total. 800. TDMA total. CDMA total. 600. PDC total. Subscribers [million]. Analogue total. Total wireless. 400. Prediction (1998). 200. 0. year. 1996. 1997. 1998. 1999. 2000. 2001. 2002. Mobile phone subscribers worldwide.

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Cellular Networks

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  1. Cellular Networks

  2. 1200 1000 GSM total 800 TDMA total CDMA total 600 PDC total Subscribers [million] Analogue total Total wireless 400 Prediction (1998) 200 0 year 1996 1997 1998 1999 2000 2001 2002 Mobile phone subscribers worldwide

  3. Mobile Services Switching Center • The MSC (mobile switching center) plays a central role in GSM • switching functions • additional functions for mobility support • management of network resources • interworking functions via Gateway MSC (GMSC) • integration of several databases • Functions of a MSC • specific functions for paging and call forwarding • termination of signaling • mobility specific signaling • location registration and forwarding of location information • provision of new services (fax, data calls) • support of short message service (SMS) • generation and forwarding of accounting and billing information

  4. Cell structure • Implements space division multiplex: base station covers a certain transmission area (cell) • Mobile stations communicate only via the base station • Advantages of cell structures: • higher capacity, higher number of users • less transmission power needed • more robust, decentralized • base station deals with interference, transmission area etc. locally • Problems: • fixed network needed for the base stations • handover (changing from one cell to another) necessary • interference with other cells • Cell sizes from some 100 m in cities to, e.g., 35 km on the country side (GSM) - even less for higher frequencies

  5. Frequency reuse patterns

  6. Development of mobile telecommunication systems CT0/1 FDMA AMPS CT2 NMT IMT-FT DECT IS-136 TDMA D-AMPS EDGE IMT-SC IS-136HS UWC-136 TDMA GSM GPRS PDC IMT-DS UTRA FDD / W-CDMA IMT-TC UTRA TDD / TD-CDMA IMT-TC TD-SCDMA CDMA IS-95 cdmaOne IMT-MC cdma2000 1X EV-DO cdma2000 1X 1X EV-DV (3X) 2G 3G 1G 2.5G Source: Prof. Dr.-Ing. Jochen Schiller, http://www.jochenschiller.de/ MC SS02

  7. Note: AMPS is an analog cellular phone system using FDMA.

  8. Figure 17.5Second-generation cellular phone systems

  9. Note: D-AMPS, or IS-136, is a digital cellular phone system using TDMA and FDMA.

  10. GSM: Overview • GSM • formerly: Groupe Spéciale Mobile (founded 1982) • now: Global System for Mobile Communication • Pan-European standard (ETSI, European Telecommunications Standardisation Institute) • simultaneous introduction of essential services in three phases (1991, 1994, 1996) by the European telecommunication administrations (Germany: D1 and D2) seamless roaming within Europe possible • today many providers all over the world use GSM (more than 184 countries in Asia, Africa, Europe, Australia, America) • more than 747 million subscribers • more than 70% of all digital mobile phones use GSM • over 10 billion SMS per month in Germany, > 360 billion/year worldwide

  11. GSM bands

  12. Performance characteristics of GSM • Communication • mobile, wireless communication; support for voice and data services • Total mobility • international access, chip-card enables use of access points of different providers • Worldwide connectivity • one number, the network handles localization • High capacity • better frequency efficiency, smaller cells, more customers per cell • High transmission quality • high audio quality and reliability for wireless, uninterrupted phone calls at higher speeds (e.g., from cars, trains) • Security functions • access control, authentication via chip-card and PIN

  13. Performance characteristics of GSM • There is no perfect system!! • no end-to-end encryption of user data • reduced concentration while driving • electromagnetic radiation • abuse of private data possible • high complexity of the system • several incompatibilities within the GSM standards

  14. Note: GSM is a digital cellular phone system using TDMA and FDMA.

  15. Note: IS-95 is a digital cellular phone system using CDMA/DSSS and FDMA.

  16. Note: The main goal of third-generation cellular telephony is to provide universal personal communication.

  17. IMT-2000 radio interfaces

  18. Satellite Networks

  19. Satellite categories

  20. Satellite orbit altitudes

  21. Table 17.1 Satellite frequency band

  22. Satellites in geosynchronous orbit

  23. Triangulation

  24. GPS

  25. LEO satellite system

  26. Iridium constellation

  27. Note: The Iridium system has 66 satellites in six LEO orbits, each at an altitude of 750 km.

  28. Note: Iridium is designed to provide direct worldwide voice and data communication using handheld terminals, a service similar to cellular telephony but on a global scale.

  29. Teledesic

  30. Note: Teledesic has 288 satellites in 12 LEO orbits, each at an altitude of 1350 km.

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