Phase Rotation Assisted Transmitter Design for QOSTBC-SM Systems.

Quasi-orthogonal space-time block code (QOSTBC) and spatial modulation (SM) have recently been integrated to reap their respective advantages as an efficient solution for down-link multiple-input multiple-output (MIMO) transmission toward application in future wireless communications. Compared with conventional space-time block coded spatial modulation (STBC-SM), quasi-orthogonal space-time block coded spatial modulation (QOSTBC-SM) can provide higher spectral efficiency. However, optimizing the system toward compensation for the performance loss caused by quasi-orthogonality remains an open challenge. In this contribution, we propose the phase rotation assisted transmitter design, aiming at further augmenting the error performance of QOSTBC-SM to a greater extent. Furthermore, the performance gains of the proposed scheme over the QOSTBC-SM systems are shown by simulation results and also quantified by the derivation of a closed-form expression for the union bound on the bit error rate (BER).