Interference issues at co-located base stations and an adaptive cancellation solution

Wireless communication service providers are having to co-locate base stations on common sites, since little space is available to build new ones. Base station receivers have to receive weak desired signals in the presence of strong transmit signals from adjacent co-located transmitters; resulting in interference and desensitisation. The paper identifies the major causes of interference and illustrates the problems with some laboratory results. The paper then describes a system that will allow many wireless communication service providers to co-exist on one common site. The system uses a reference antenna to drive an adaptive cancellation loop that cancels the interfering signals. Simulations in Advanced Design Systems show that a cancellation of about 65dB is achievable.