A modified sequential beamforming algorithm for cochannel IS-136 signals

Cochannel signals in a time-division multiple-access (TDMA) cellular network interfere with each other in an asynchronous manner. In order to demodulate one of these signals, the receiver must be able to separate the cochannel interferers for a variety of burst overlap scenarios. We present an adaptive beam-forming algorithm that separates cochannel IS-136 signals using the known synchronization sequences. It employs constrained least-squares algorithms that process the antenna data in two sequential passes. In this way, the data are accurately beamformed within a burst even when the cochannel scenario changes during the burst.