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Cellular Telephony - Architecture

Cellular Telephony - Architecture. Duplex Communication - FDD. FDD: Frequency Division Duplex. Base Station B. Mobile Terminal M. Forward Channel. Reverse Channel. Forward Channel and Reverse Channel use different frequency bands. Frequency. Frequency. Time. Time. Frequency. Time.

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Cellular Telephony - Architecture

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  1. Cellular Telephony - Architecture

  2. Duplex Communication - FDD • FDD: Frequency Division Duplex Base Station B Mobile Terminal M Forward Channel Reverse Channel Forward Channel and Reverse Channel use different frequency bands

  3. Frequency Frequency Time Time Frequency Time Access Methods FDMA TDMA CDMA

  4. Very Basic Cellular/PCS Architecture Mobility Database Public Switched Telephone Network Base Station Controller Mobile Switching Center (MSC) Radio Network Base Station (BS) Mobile Station

  5. Clusters • A cluster is a group of cells • No channels are reused within a cluster A seven Cell Cluster

  6. Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service Reverse Channel Forward Channel 991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799 824-849 MHz 869-894 MHz Channel Number Center Frequency (MHz) Reverse Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 825.0 0.030(N-1023) + 825.0 Forward Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 870.0 0.030(N-1023) + 870.0 (Channels 800-990 are unused) Channel bandwidth is 45 MHz

  7. Frequency Reuse • Only a small number of radio channel frequencies were available for mobile systems • Therefore engineers had to find a way to reuse radio channels to carry more than one conversation at a time • The solution the industry adopted was called frequency reuse. Implemented by restructuring the mobile telephone system architecture into the cellular concept

  8. Frequency Reuse • The concept of frequency reuse is based on assigning to each cell a group of radio channels used within a small geographic area • Cells are assigned a group of channels that is completely different from neighbouring cells • The coverage area of cells is called the footprint and is limited by a boundary so that the same group of channels can be used in cells that are far enough apart

  9. Frequency Reuse • Cells with the same number have the same set of frequencies Frequency Reuse

  10. Cell Frequency Reuse

  11. f2 f7 f3 f1 f6 f4 f5 Frequency Reuse using 7 frequencies allocations f2 f7 f3 f1 f6 f4 f2 f5 f2 f7 f3 f7 f3 f1 f2 f1 f6 f4 f7 f3 f6 f4 f5 f1 f5 f6 f4 f5 Each cell is generally 4 to 8 miles in diameter with a lower limit around 2 miles.

  12. Locating Cells N=19 (i= 3, j=2)

  13. Cell Splitting • Allows urban centres to be split into as many areas as necessary for acceptable service levels in heavy-traffic regions, while larger, less expensive cells can be used to cover remote rural regions

  14. Cellular Concept with Sectors frequency re-use base station

  15. Hand-off • The final obstacle in the development of the cellular network involved the problem created when a mobile subscriber moved from one cell to another during a call

  16. Looking to PCS from different Angles Internet PSTN (Telephone Network) Wireless Access • Mobile Users • Laptop users • Pocket PC users • Mobile IP, DHCP enabled computers • Mobile Users • Cell phone users • Cordless phone users Telecom People View Data Networking People View

  17. Telecom and Data Networking Telecom Interest Data Networking Interest • - Voice Transmission • - Frequency Reuse • Handoff Management • Location Tracking • Roaming • QoS • GSM, CDMA, Cordless Phones, • GPRS, EDGE • Data Transmission • Mobile IP (integrating mobile hosts to internet) • Ad-hoc Networks • TCP over Wireless • Service Discovery • Radio Propagation • Link Characteristics • Error Models • -Wireless Medium • Access (MAC) • - Error Control

  18. Major Mobile Radio Standards USA

  19. Major Mobile Radio Standards - Europe

  20. Example - Frequency Spectrum Allocation in U.S. Cellular Radio Service Reverse Channel Forward Channel 991 992 … 1023 1 2 … 799 991 992 … 1023 1 2 … 799 824-849 MHz 869-894 MHz Channel Number Center Frequency (MHz) Reverse Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 825.0 0.030(N-1023) + 825.0 Forward Channel 1 <=N <= 799 991 <= N <= 1023 0.030N + 870.0 0.030(N-1023) + 870.0 (Channels 800-990 are unused) Channel bandwidth is 45 MHz

  21. 2G Technologies

  22. GSM Speech Signal Processing

  23. GSM Networks

  24. GSM Signaling Protocol Architecture

  25. GSM and CDMA Coverage Map Worldwide

  26. Upgrade Paths for 2G Technologies 2G IS-95 GSM IS-136PDC 2.5G GPRS HSCSD IS-95B EDGE 3G cdma200-1xRTT W-CDMA EDGE cdma2000-1xEV,DV,DO TD-SCDMA cdma200-3xRTT

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