L7b_cellular - Page 1 EEC173B/ECS152C, Spring 2010 Cellular...

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Unformatted text preview: Page 1 EEC173B/ECS152C, Spring 2010 Cellular Wireless Network Architecture and Protocols Applying concepts learned in first two weeks: ‐ Frequency planning, channel allocation & hand ‐ offs 2 Terminology Wireless Wide ‐ Area Network (WWAN) ‐ E.g., UMTS, 3G, CDMA, GSM Wireless Metropolitan ‐ Area Network (WMAN) ‐ Usually spanning a city, e.g., WiMax Wireless Local ‐ Area Network (WLAN) ‐ E.g. IEEE 802.11 (Wi ‐ Fi) Wireless Personal ‐ Area Network (WPAN) ‐ E.g., IrDA (Infrared), Bluetooth, UWB, Z ‐ Wave and ZigBee. 3 Wireless Wide ‐ Area Networks (WWANs) Early mobile system achieves large coverage area by using a single, high powered transmitted with an antenna mounted on a tall tower ‐ E.g., Bell mobile system in New York City (1970s) could support 12 simultaneous calls over a thousand square miles Cellular concept was a major breakthrough to solve the problem of spectral congestion and user capacity ‐ Replace single, high power transmitted (large cell) with many low power transmitters (small cells) ‐ Each base station (BS) gets a portion of the total number of channels ‐ Neighboring BSs are assigned different groups of channels so that interference is minimized => Wireless Cellular Networks! 4 1 st Generation Cellular System: AMPS Advanced Mobile Phone System (AMPS) ‐ Divides 800 MHz spectrum into several channels, each 30 KHz wide => 832 full ‐ duplex channels ‐ Cellular structure uses cluster size of seven ( N=7 ), r=10 ‐ 20 Km ‐ Use concept of trunking (as in phone networks) ‐ Grade ‐ of ‐ service (GoS) measures network accessibility, i.e., probability of call being block or experiencing a queuing delay greater than a threshold value • AMPS is designed for GoS=2% 5 Problems with 1G Systems No use of encryption Inferior call quality ‐ Analog traffic is degraded by interference. In contrast to digital traffic, no coding or error correction is applied Spectrum inefficiency ‐ Dedicated channel allocated per user ‐ Unlike digital signals that allow compression, cannot reduce amount of capacity needed to send data 2G systems 2G systems are Digital: convert speech into digital code (a series of pulses) 6 2 nd Generation: 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...
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This note was uploaded on 04/29/2010 for the course ECS 152 taught by Professor Mr. during the Spring '10 term at University of Great Falls.

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L7b_cellular - Page 1 EEC173B/ECS152C, Spring 2010 Cellular...

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