Hybrid Spatial Modulation Scheme with Arbitrary Number of Transmit Antennas.

Spatial Modulation (SM) is a single RF chain Multi-Input-Multi-Output (MIMO) scheme that has significantly improved the spectral efficiency. A major limitation of SM is the constraint on the number of transmit antennas, where the number of transmit antennas must be a power of two. Generalized SM (GSM) is proposed to further improve the spectral efficiency of SM by activating multiple transmit antennas simultaneously. However, activating multiple antennas increases the energy consumption at the transmitter. To this end, a hybrid scheme is proposed in this paper that allows for arbitrary number of transmit antennas to be installed. For a given number of transmit antennas, the proposed scheme achieves higher spectral efficiency than SM. Also, for a given spectral efficiency, the proposed scheme consumes energy less than GSM, and causes a negligible loss in the error performance compared to SM and GSM.