Quasi-Orthogonal Space-Time Block Codes based on circulant matrix for eight transmit antennas

For using in multiple transmits antennas systems, a number of Quasi-Orthogonal Space-Time Block Codes (QOSTBC) has been proposed. Based on circulant matrix, in this paper, we propose a novel method of extending any QOSTBC constructed for 8 transmit antennas to a closed-loop scheme. We prove that the proposed scheme can improve its transmit diversity with one bit feedback, with the aid of multiplying the entries of QOSTBC code words by the appropriate phase factors which depend on the channel information. The optimal constellation rotated schemes as well as performances of the proposed scenario 8 transmit antennas QOSTBC are analyzed. The simulation results suggest that there is a significant Eb/No advantage in the proposed scheme which is able to be designed easily.