Improving the Performance of Spatial Modulation Schemes for MIMO Channels

Spatial modulation (SM) is a recent MIMO transmission concept that holds the potential to increase the spectral efficiency over wireless links using low-complexity transceivers. In this paper, an overview and performance analysis on the key issues of this emerging technology is presented. Based on this analysis, a performance enhancement is suggested by introducing an improved spatial modulation (ISM) scheme that retains the SM key advantages. It is observed that transmitting the same data symbol from more than one antenna at a time has a positive effect in terms of spectral efficiency but, on the other hand, it degrades the bit error rate (BER) performance. In this sense, a more general SM mapping rule is introduced aiming to provide a criterion for choosing an effective performance/rate/complexity trade-off according to the system requirement. An upper bound on the BER performance for ISM is derived and compared to Monte Carlo simulation results. In addition, a two-stage adaptive detector is also presented to enhance further the performance/complexity trade-off at the receiver for SM-based techniques.