A differential scheme for Spatial Modulation

In this paper, by considering the case of two transmit antennas, we propose a novel approach for introducing differential signaling into Spatial Modulation (SM)/Space-Shift Keying (SSK) and thus develop a differential SM/SSK (DSM/DSSK) scheme, where neither the transmitter nor the receiver has access to channel state information. The proposed approach can be applied to any equal energy signal constellations. Performance analysis of the proposed DSM is developed analytically and demonstrated via simulations, leading to some interesting observations and useful conclusions. It is shown that the performance degradation of DSM over SM can be less than 3dB and that the loss decreases as the number of receive antennas decreases.