Few More Quasi-Orthogonal Space-Time Block Codes for Four Transmit Antennas

In this paper, we derive few new quasi-orthogonal space-time block codes for four transmit antennas. These codes differ from each other and existing codes in character matrices and/or correlated values in character matrices. These codes can be constructed using elementary sub-matrices. We also derive corresponding maximum-likelihood decoders for the proposed codes. We observe that decoding complexity of some of these codes is less as compared to the rest of them for rectangular-QAM modulation. Bit error rate performance of these codes have been shown to be same as those of existing quasi-orthogonal space time block codes for four transmit antennas over quasi-static flat Rayleigh fading channels.