A GMSK Receiver with Beamformer Weight Refinement

Abstract

We present an adaptive antenna algorithm for Gaussian minimum-shift keying (GMSK)-based cellular systems with beamformer weights that are iteratively computed using re-encoded data to suppress cochannel interference (CCI). Filtered training sequences are proposed in order to compensate for the effects of timing offsets that occur for asynchronous cochannel signals. Also, we extend the receiver to include a linear equalizer that mitigates intersymbol interference (ISI). Various multistage receivers incorporating the proposed beamformer and equalizer algorithms are presented. Their performance is evaluated using simulated and real time-division multiple-access (TDMA) data, demonstrating that the proposed beamforming algorithms suppress CCI and significantly improve the performance compared to a conventional GMSK receiver.