A modified sequential beamforming algorithm for cochannel IS-136 signals

Abstract

Cochannel signals in a time-division multiple-access (TDMA) cellular network interfere with each other in an asynchronous manner. I n order to demodulate one of these signals, the receiver must be able to separate the cochannel interferers for a variety of burst overlap scenarios. I n this paper, we present an adaptive beamforming 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.