FREQUENCY REUSE

The design process of selecting and allocating channel groups for all of the cellular base stations within a system is called " Frequency Reuse" or "frequency planning".

                          IN cellular system we know that large area is divided into small cells . Each cell is provided with set of radio channels , which are different from the neighbour cell's allocated radio channels.
This is done in order to avoid frequency interference .
But the available bandwidth of frequency for cellular communication is less and if we assign as mentioned above then we will be able to cover only a small area.

FREQUENCY REUSE CONCEPT:
                    In this system a "cluster" (Group of cells) is created of particular size of 4, 7,12 etc.
Each cell in a cluster is assigned with different set of radio channels . But a cell in cluster will be assigned with same set of channels as a cell in another cluster so as to increase the capacity of cellular network.

"Frequency reuse pattern"

If each cell is allocated a group of "k" channels and if s channels are divided among N cells then

number of available radio channels is 

S=KN 

capacity is given by:

C=MKN=MS 

Where M is the no of times cluster repeated .