A New Rate 3/4 Transmit Diversity for Five and Six Transmit Antennas with Phase Feedback

We present a rate 3/4 transmit diversity scheme for five or six transmit antennas. The new code provides a diversity order 4 and the same rate as quasi-orthogonal space-time block code (QOSTBC) which has a diversity order 3. Based on the perfect channel phase feedback (CPF) from the receiver to the transmitter, a precoding is employed at the transmitter to assure the acquirement of the full diversity. We also derive the closed-form expression for phase feedback, which is only the function of the channel gains known to the receiver. Moreover, decoding complexity is reduced by the partial linear and symbol-pair maximum likelihood (ML) decoding. Analyzing and simulation results confirm that the proposed transmit diversity scheme outperforms QOSTBC