Interference resulting from signals which are close in frequency to the desired signal is called adjacent channel interference.

Adjacent channel interference results from imperfect receiver filters which allow nearby frequencies to leak in to pass band.

It is serious problem can be a particularly serious if an adjacent channel user is transmitting very close range to a subscribers receiver, while receiver attempts to receive a BS on the desired channel this is referred to as near far effect

The adjacent channel interference can be reduced by

1) Careful filtering

2) Careful channel assignment.

• There should be adequate frequency separation between the spectrum of the adjacent channels in a cell
• If the frequency reuse factor is large or cluster size is small the adjacent channel at the base station will be too close to each other in the frequency domain and this will increase the interference.