Precoding-Aided Spatial Modulation With Increased Robustness to Channel Correlations

We present a precoding approach for spatial modulation (SM) for increased robustness against spatial correlations over slow fading Rayleigh channels. This approach, based on phase-rotation of the transmitted symbol according to the active transmit antenna, can be implemented without changing the power budget or needing any explicit knowledge of the channel state information at the transmitter. The optimum precoding coefficients are determined so as to minimize the asymptotic average bit-error rate. Both theoretical analysis and simulation results indicate significant performance improvements even in the case of heavily correlated transmit antennas.