Evaluation of QO-STBC Schemes for Four Transmit Antennas

In this paper, we evaluate a few quasi-orthogonal space-time block coding (QO-STBC) schemes for four transmit antennas. Recently, QO-STBC with minimum decoding complexity (MDC-QO-STBC) was proposed. We provide a new analysis result on MDC-QO-STBC. We show that the encoding matrix of the MDC-QO-STBC is equivalent to the conventional QO-STBC. We also prove that this scheme can be linearly decoded at the receiver. This is achieved by modification of the encoding matrix via rotation of the channel correlation matrix.