Receive Spatial Modulation for LOS mmWave Communications Based on TX Beamforming

Receive spatial modulation (RSM) is a recently introduced multi-antenna transmission scheme that is capable of achieving high spectral efficiency at low hardware and processing complexity. We study RSM for application in indoor line-of-sight (LOS) millimeter-wave (mmWave) communication. Significantly different from low-gigahertz indoor channels, which are typically modeled by a Rician distribution, indoor mmWave channels are sparsely-scattered and dominated by LOS propagation. Hence, we consider the specific characteristics of the LOS mmWave channel and identify the channel conditions that minimize the symbol error probability (SEP) of RSM. We prove that the SEP of RSM in a LOS channel is minimized by imposing orthogonality conditions to the channel matrix. In addition, we propose a simple hardware architecture for the transmitter (TX), which uses only RF phase shifters for precoding. Simulation results show that RSM can successfully operate in indoor mmWave channels.