Complex orthogonal space-time block codes rates 3/7, 4/8 and 6/8 for 3, 4 and 4 transmit antennas in space time coding

Space-time block codes from orthogonal design have two advantages, namely, fast maximum - likelihood (ML) decoding and full diversity. Rate 1 real space -time codes (real orthogonal design) for multiple transmit antennas have been constructed from the real Hurwitz - Radon families, which also provides the rate ½ complex space-time codes (complex orthogonal designs) for any number of transmit antennas. Rate ¾ complex orthogonal designs (space - time codes) for three and four transmit antennas have existed in the literature but no high rate (>;1/2) complex orthogonal designs for other numbers of transmit antennas exist. In this correspondence, we present rates 3/7, 4/8 and rate 6/8 generalized complex orthogonal designs for three, four and four transmit antennas, respectively.