School of Information, Computer and converse Technology
ECS 445: Mobile Communications The Cellular Concept
Prapun Suksompong, Ph.D. prapun@siit.tu.ac.th November 22, 2009
This note covers fundamental cellular receiving set concepts which are at the core of providing wireless dialogue service to subscribers on the move using deposited radio spectrum.
Contents
1 Cellular Telephone organizations 2 Frequency use 3 Cell planing with hexagonal cells 4 Co-Channel Interference 5 Trunking 6 Improving Coverage and Capacity 1 4 7 10 13 14
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Cellular Telephone Systems
1.1. receiving set telephone system should be structured to achieve high school capacity with limited radio spectrum while at the uniform time covering very large areas.
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1.2. Older System: Achieve a large coverage area by using a simple, high powered transmitter. ? Put BS on top of mountains or tall towers, so that it could win coverage for a large area. The next BS was so far away that interference was not an issue. Severely limit the number of users that could communicate cooccurringly. Noise-limited system with few users.
The Bell restless system in New York City in the seventies could only support a maximum of twelve cooccurring calls over a thousand square miles. 1.3. The number of simultaneous calls a mobile wireless system can stick is essentially determined by the total spectral storage allocation for that system and the heapwidth required for transmitting signals used in treatment a call. Example 1.4. Using a typical running(a) system, each channel needs to have a bandwidth of virtually 25 kHz to enable su?cient audio quality to be carried, as well as allowing for a guard band between adjacent signals to ensure there are no undue levels of interference. Using this concept, it is possible to accommodate only forty users in a frequency band 1-MHz wide. Even if one C MHz were allocated to the system, this would enable only 4000 users...If you want to get a full essay, order it on our website: Orderessay
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