Separation of cochannel signals in TDMA mobile radio

In this paper, we propose a sequential algorithm that separates cochannel time-division multiple-access (TDMA) signals that encounter multipath interference and noise. The receiver employs a multistage architecture where each stage consists of a beamformer and an equalizer that isolates one source, compensates for intersymbol interference (ISI), and demodulates the data. A problem encountered with such bursty sources is that the beamformer/equalizer trained for a particular time slot may not be appropriate for all the data contained in that slot. This occurs because a cochannel source typically overlaps only part of the time slot of interest and may not overlap the training sequence at all. The algorithm presented here overcomes this problem by processing the data forward and backward in a sequential noncausal manner. Computer simulations using signals with the IS-54 format are presented to demonstrate the properties of the sequential algorithm.