Performance Analysis of Spatial Modulation with Multiple Decode and Forward Relays

Spatial modulation (SM) is a multiple-input multiple-output (MIMO) transmission scheme that draws momentous attention lately due to its reported performance enhancements over other MIMO techniques. However, a major drawback of SM system is that the achieved diversity gain is limited to the number of receive antennas and poor performance is reported for small number of receive antennas. Therefore, it is the aim of this paper to study the performance of SM with multiple decode and forward (DF) relays in which the relays that correctly detect the source signal forward the decoded message to the destination in pre-determined orthogonal channels. A closed form expression of the pair wise error probability (PEP) is obtained for a system consisting of two transmit antennas, multiple DF relays and single receive antenna. As well, asymptotic expression for the PEP at high signal to noise ratio (SNR) is derived. It is shown that significant performance enhancements can be achieved and the derived analysis is validated through Monte Carlo simulation results.