How a Mobile Call is Actually Made?

How a Mobile Call is Actually Made?

In order to know how a mobile call is made, we should rst look into the basics of
cellular concept and main operational channels involved in making a call. These are
given below.
1.5.1 Cellular Concept
Cellular telephone systems must accommodate a large number of users over a large
geographic area with limited frequency spectrum, i.e., with limited number of channels.
If a single transmitter/ receiver is used with only a single base station, then
sucient amount of power may not be present at a huge distance from the BS.
For a large geographic coverage area, a high powered transmitter therefore has to
be used. But a high power radio transmitter causes harm to environment. Mobile
communication thus calls for replacing the high power transmitters by low power
transmitters by dividing the coverage area into small segments, called cells. Each
cell uses a certain number of the available channels and a group of adjacent cells
together use all the available channels. Such a group is called a cluster. This cluster
can repeat itself and hence the same set of channels can be used again and again.
Each cell has a low power transmitter with a coverage area equal to the area of the

cell. This technique of substituting a single high powered transmitter by several low
powered transmitters to support many users is the backbone of the cellular concept.