Reconfigurable Intelligent Surface Assisted Transmitter Pre-Coding Spatial Modulation.

Reconfigurable intelligent surface (RIS) is a vital enabler of paradigm-shifting transmission technologies for next-generation wireless. In this paper, we propose a RIS-assisted transmitter pre-coding spatial modulation (RIS-PSM), such that the transmission reliability of the PSM-modulated multiple-input multiple-output systems can be remarkably enhanced. To fulfil our novel design, a two-phase decision process (TPDP) based optimization algorithm is propounded that the optimal transmitter pre-coding vector and RIS reflection matrix can be derived in closed-form jointly. In addition, we introduce two receive detection algorithms, namely the optimal co-detection (OCD) and the sub-optimal detached detection, in order that the indices of the designated receive antenna and the based-band modulated signal can be reliably detected with different levels of computational complexity. Eventually, the ideally achievable error performance is evaluated by considering the RIS-PSM with the detection of OCD. Simulation and numerical results are depicted to reveal the superiorities of the proposed system, as well as to substantiate the accuracy of the performance analysis.