The Cellular Concept

The Cellular Concept
The cellular concept[2] was a major breakthrough in solving the problem of spectral congestion
and user capacity. It offered high capacity with a limited spectrum allocation without any major
technological changes. The cellular concept is a system level idea in which a single, high power
transmitter (large cell) is replaced with many low power transmitters (small cells). The area
serviced by a transmitter is called a cell. Each small powered transmitter, also called a base
station provides coverage to only a small portion of the service area. Base stations close to one
another are assigned different groups of channels so that all the available channels are assigned
to a relatively small number of neighboring base stations. Neighboring base stations are
assigned different groups of channels so that the interference between base stations is
minimized. By symmetrically spacing base stations and their channel groups throughout a
service area, the available channels are distributed throughout the geographic region and may be
reused as many times as necessary, so long as the interference between co-channel stations is
kept below acceptable levels.
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As the demand for service increases, the number of base stations may be increased, thereby
providing additional capacity with no increase in radio spectrum. This fundamental principle is
the foundation for modern mobile communication systems, since it enables a fixed number of
channels to serve an arbitrarily large number of subscribers by reusing the channels throughout
the region. The concepts of frequency reuse, handoff and system capacity are explained in next post