Design of new concatenated space-time block codes using odd transmit antennas

In this paper, a new class of space-time block codes achieving full-rate and full spatial diversity for QAM is proposed when using any odd transmit antennas over quasi-static Rayleigh fading channels. Like the conventional A-ST-CR codes [10], the proposed codes are constructed by serially concatenating the constellation-rotating precoders [7]-[9] with the Alamouti scheme [3]. Computer simulations show that for the case of QPSK, the best code in this class achieves approximately 1.5dB larger coding gain than the existing ST-CR code [8], [9] for both 3 and 5 transmit antennas at average SER= 10(-5) and for the case of 16-QAM, 3dB for 3 transmit antennas. The codes possessing quasi-orthogonal characteristic are also included in this class, allowing simple ML decoding with virtually no performance loss compared to the best code in the class.