Improved array processing for two-user detection of Alamouti code

Recently, it is shown in [1] that by interference cancellation through zero-forcing a diversity order of 2(M −1) can be achieved in a multiple access channels (MAC) based uplink two-user MIMO system with two transmit antennas at each user and M >2 receive antennas at the base-station. In this paper, we show that by using improved array processing technique a diversity order of 2M can be achieved in a two-user interference cancellation system with two transmit and more than two receive antennas. We derive pairwise error probability (PEP) bounds for different number of receive antennas and prove the diversity order for different cases theoretically.