Enhanced adaptive antenna algorithms for asynchronous TDMA systems

Adaptive beamforming algorithms are presented for time-division multiple-access (TDMA) systems that use Gaussian minimum-shift keying (GMSK) for the transmitted signals. A semi-blind beamforming algorithm based on a least-squares (LS) approximation for constant modulus signals leads to a relatively simple and practical receiver that suppresses cochannel interference (CCI). In order to further improve the receiver performance, filtered training sequences are used to compensate for the phase offsets of the cochannel GMSK signals. Computer simulations demonstrate that this hybrid algorithm improves the receiver performance, whereby the beampattern nulls suppress the CCI affecting the coded data of the TDMA bursts.