Reconfigurable Intelligent Surface-Based Symbiotic Radio for 6G: Design, Challenges, and Opportunities
Xianfu Lei, Mingjiang Wu, Fuhui Zhou, Xiaohu Tang, Rose Qingyang Hu, Pingzhi Fan
Abstract
Energy efficiency (EE) and spectrum efficiency (SE) are two key performance metrics in the sixth generation (6G) wireless communication networks due to the ultra-massive connectivity requirements in future Internet of Things scenarios such as smart cities and factories. Reconfigurable intelligent surface (RIS)-based symbiotic radio (SR) is a promising technology to simultaneously achieve high EE and SE. In this article, a comprehensive review of the RIS-based SR system is presented including the system architectures, operating principles, technical advantages, application scenarios and state-of-the-art transceiver design. Moreover, a star-QAM-aid-ed joint spatial modulation scheme is proposed to realize RIS-based SR and simulation results are provided to illustrate the performance of the proposed scheme. Finally, the critical design challenges for the implementation of RIS-based SR and some promising future research directions are discussed.