Interference: 

•Interference is a one of the major factor affecting the performance of cellular radio system. Source of interference consists of another mobile inside the same cell, an ongoing cal in a neighbour cell,other base station transmitting signal in the same frequency band or any non cellular system which accidentally transmits energy into the cellular frequency band.
•Interference on voice signal would give rise to crosst where the caller hears interference in the background due to the presence of unwanted transmission.
•The presence of interference in control channels give rise to missed and block the callss.
•Interference has best accepted as a major obstruction in increasing the capacity of a system and is largely responsible for dropped calls in a network.

The two major types of interference:

1- Co-channel interference
     The channel reuse approach is very useful for increasing the efficiency of radio spectrum utilisation but it is result in ko channel interference because the same radio channel is repeatedly using different co-channel cells in a network. In this case the quality of received signal is very much affected both by the amount of radio coverage area and co channel interference.
      Co channel interference take place when two or more transmitter located within a wireless system even on neighbours wireless system, which are transmitting on the same radio channel.

2- Adjacent channel interference
    Signals from neighbours radio channels are also called adjacent channel, leak into the particular channels thus causing adjacent channel interference.
     Adjacent channel interference take place due to the inability of a mobile phone to separate out the signals of adjacent channels allocated to neighbours cell site.