A multiuser space-time block coding system with squaring method

A multiuser orthogonal space-time block coding (STBC) system in a Rayleigh flat-fading channel with a squaring method is proposed. Soft interference suppression in the multiuser demodulator is combined with the iterative MAP decoding algorithm in the receiver and a squaring method is introduced to eliminate the need to conjugate the received signals and the path gains by doubling the soft code vector, which is fit for all orthogonal STBC designs. The computation complexity keeps same because about half of the elements in the transmission matrix are 0. The channel mismatch has also been studied using pilot symbols. The simulation results confirm the validity of the proposed squaring method. About 1dB SNR improvement over otherwise similar techniques has been obtained with same iteration times. The channel mismatch leads to about 1dB SNR loss at the same BER performance.