An Overview of Spatial Modulation Techniques for Millimeter Wave MIMO Systems

The emerging of millimeter wave (mmWave) communications has been widely predicted to revolutionize the traditional communications. On one hand, the large bandwidth provided by mmWave is orders of magnitudes larger than that provided by current microwave communications, which therefore supports much higher throughput as well as massive connectivity. On the other hand, the small wavelength of mmWave signals facilitates the application of massive antennas, thus benefiting from the powerful multiple-input multiple-output (MIMO) beamforming and other MIMO signal processing techniques. However, mmWave-MIMO systems often suffer from prohibitive power consumption due to the massive antennas and radio frequency (RF) chains. Spatial modulation (SM) techniques have been proposed as a low-complexity, low-power-consumption MIMO candidate. More importantly, the idea of incorporating SM techniques into mmWave-MIMO systems has been proved effective for reducing the number of radio frequency (RF) chains, to which many research efforts have been devoted. This paper provides a comprehensive overview of the combination of SM and mmWave communications, with a special emphasis on the hybrid beamforming regimes for SM-motivated mmWave-MIMO systems