• Each cellular base station is allocated group of radio channels to be used within a small geographic area called “cell” .Base stations in adjacent cells are assigned channel group which contains completely different channels than neighbouring cell.

• By limiting coverage area to within the boundaries of cell, the same group of channels may be used to cover different cells that are separated from one another by distance large enough to keep interference level within tolerable limits.

• The design process of selecting and allocating channel groups for all the cellular base station within a system is called frequency reuse or frequency planning. Frequency reuse is important as the spectrum allocated for cellular transmission is limited and demand is increasing rapidly.

For N=7

For N=4