Low-Complexity Detection Schemes for QOSTBC With Four-Transmit-Antenna

In this letter, we propose two improved decoding algorithms based on traditional low-complexity maximum likelihood (LC-ML) detection algorithm for the quasi-orthogonal space-time block code (QOSTBC) with four-transmit-antennas. The decoding complexities of the proposed algorithms are both lower than LC-ML decoder. By decomposing the channel matrix and its elementary transformation form with QR decomposition, the first algorithm can detect the four signals independently at the cost of some BER performance penalty whereas the second algorithm achieves almost the same BER performance with LC-ML decoder by using the interference cancellation method twice.