Pre-equalization for MIMO Wireless Systems Using Spatial Modulation

Spatial modulation (SM) has emerged as a very promising method to exploit the potential multiple-input multiple-output system gains using low-complexity transceivers. SM uses the antenna index at the transmitter as an additional source of information. Although SM avoids inter-channel interference, its performance tends to decrease when the number of constellation points per antenna grows up. The main contribution of this paper is to introduce a novel pre-equalization stage for SM which allows to mitigate the fading effect of the wireless channel. Its principle is to pre-distort the points generated by SM, so that the receiver has an approximation of a M-QAM scheme, where the minimum distance between constellation's points is increased and consequently, the system's performance is improved. In order to perform the pre-equalization, a complete channel state information is assuming at the transmitter. It is shown through Monte Carlo simulations that the proposed scheme significantly enhances the performance of SM.