Space–Time Block Codes With Symbol-by-Symbol Maximum-Likelihood Detections

This paper presents a new set of quasi-orthogonal space-time block codes (QOSTBCs) with symbol-by-symbol maximum-likelihood (ML) detections for four Tx antennas over quasi-static Rayleigh fading channels. Each of the codes is analytically proved to achieve full transmit diversity and the same coding gains as the rate-1 coordinate-interleaved orthogonal design by individually using their optimal constellation rotations over arbitrary quadrature amplitude modulation (QAM) or 4M -phase-shift keying (PSK) constellations. Previous designs are included in the systematic formulation as well. Combining with simulation, the coding loss paying for simplifying the optimal decoders from complex-symbol-pairwise to symbol-by-symbol ML detections is found asymptotically equal to 0.21 dB, for the QOSTBCs achieving full transmit diversity and the optimal coding gains over general QAM constellations.