GSTBC-SM Assisted High Diversity Reconfigurable Intelligent Surface Systems

In this paper, generalized space-time block-coded (GSTBC) spatial modulation (SM)-assisted reconfigurable intelligent surface (RIS) structures are designed for three communication scenarios, where RIS works as a transmitter, passive relay as well as active relay. Specifically, the information bits are first mapped to an appropriate GSTBC-SM symbol according to the required transmit rate and diversity order. Then, the mapped GSTBC-SM symbol is transmitted by the based station or the RIS elements based on the communication scenario. Both the signal detector and the upper bounds of average bit error probability are derived for the three cases, which are verified by the simulation results. Simulation results show that the proposed GSTBC-SM-RIS scheme is capable of providing a significant performance gain over the existing SM-RIS scheme, as well as the conventional GSTBC-SM counterpart.