Low Complexity Interference Rejection Combining for MLSE

Abstract

Co-channelinterference and inter-symbol interference (ISI) are common problems encountered by modern wireless communication systems. To mitigate these challenges, diversity antennas with optimum combining can be used in conjunction with the maximum likelihood sequence estimator (MLSE) to achieve the optimum receiver in a time dispersive propagation environment. We derive a simple multi-antenna MLSE receiver structure that is optimum in diversity combining and equalization given the spatial correlation of the interference and noise. The Viterbi sequence estimation within the multiantenna receiver has the same complexity as a single-antenna receiver. Since the spatial covariance of the noise is taken into account in the ML sequence estimate, strong co-channel interference can be effectively suppressed. The receiver's robust interference rejection capability is validated in simulations of the GMSK-modulated GSM signal.