Interplay Between Reconfigurable Intelligent Surfaces and Spatial Modulation: New Application Paradigms

Reconfigurable intelligent surface (RIS)-assisted transmission and spatial modulation (SM) are capable of achieving both high spectral efficiency and high energy efficiency. The amalgamation of RISs and SM emerges as a highly competitive paradigm for future wireless networks. However, most of the existing works on RIS-SM place emphasis on the design of end-to-end modulation/demodulation schemes. Differently, this article focuses on the applications of RIS-SM in a variety of scenarios. It first provides an overview of the SM family and the RIS technology, followed by discussions on the interplay between SM and RISs. The potential applications of RIS-SM are then investigated in relay networks, wireless sensor networks (WSNs), and cognitive radio by exploiting the two informationcarrying units of the SM technologies and the RISs' capability of reconfiguring the wireless environment. The effectiveness and superiority of RIS-SM is verified by taking the application to WSNs as an example. We finally discuss the research challenges and future work regarding RIS-SM.