Editing Cellular network (section)

== Concept ==
{{More citations needed section|date=February 2025}}
[[File:frequency reuse.svg|thumb|Example of frequency reuse factor or pattern, with four frequencies (F1-F4)]]
In a [[cellular radio]] system, a land area to be supplied with radio service is divided into cells in a pattern dependent on terrain and reception characteristics. These cell patterns roughly take the form of regular shapes, such as hexagons, squares, or circles although hexagonal cells are conventional. Each of these cells is assigned with multiple frequencies (''f''<sub>1</sub>&nbsp;–&nbsp;''f''<sub>6</sub>) which have corresponding [[radio base station]]s. The group of frequencies can be reused in other cells, provided that the same frequencies are not reused in adjacent cells, which would cause [[co-channel interference]].

The increased [[Channel capacity|capacity]] in a cellular network, compared with a network with a single transmitter, comes from the mobile communication switching system developed by [[Amos E. Joel Jr.|Amos Joel]] of Bell Labs<ref>{{US patent|3,663,762}}, issued 16 May 1972.</ref> that permitted multiple callers in a given area to use the same frequency by switching calls to the nearest available cellular tower having that frequency available. This strategy is viable because a given radio frequency can be reused in a different area for an unrelated transmission. In contrast, a single transmitter can only handle one transmission for a given frequency. Inevitably, there is some level of [[co-channel interference|interference]] from the signal from the other cells which use the same frequency. Consequently, there must be at least one cell gap between cells which reuse the same frequency in a standard [[frequency-division multiple access]] (FDMA) system.

Consider the case of a taxi company, where each radio has a manually operated channel selector knob to tune to different frequencies. As drivers move around, they change from channel to channel. The drivers are aware of which [[frequency]] approximately covers some area. When they do not receive a signal from the transmitter, they try other channels until finding one that works. The taxi drivers only speak one at a time when invited by the base station operator. This is a form of [[time-division multiple access]] (TDMA).