Highly spectral-efficient spatial modulation using quasi-orthogonal sequences

In this paper, we propose a new spatial modulation (SM) scheme using quaternary quasi-orthogonal sequences (Q-QOSs) for any multiples of four transmit antennas. The new scheme is an extended work of conventional Q-QOS-SM, which is designed only for antennas of powers of two. Unlike the original Q-QOS-SM, the new scheme adopts the QOS of length 4 for all applied antennas, which enables more design flexibility over an antenna size, and also guarantees much higher bit rate with given antennas. Simulation results show that the proposed scheme achieves greatly improved throughput compared to conventional other schemes for all simulation cases.