Cellular Communications Explained

sufficient channels to allow all the subscribers to gain access or, alternatively, when changing from

one cell to the next there may be no free channels and the call is then dropped. Dropping calls

is obviously not popular with subscribers, and if the levels of dropped calls rise too high then the

subscriber is likely to move to another network, thereby increasing what is called the ‘churn’ rate

(the rate at which subscri bers move from one network to the next).

In order to judge the capacity requirement for a system it is necessary to look at the average time

each subscriber is likely to use the system, the number of subscribers, and what the peaks in usa ge

are likely to be. In general it is found that usage is high over most of the working day, ...