A Comprehensive Survey on Reconfigurable Intelligent Surfaces for Smart Radio Environments

Abstract

RISs are revolutionizing the development of future wireless networks by allowing transmission signals to be carefully adjusted and managed in wireless channels. RISs improve spectral efficiency, energy efficiency, coverage, and security using the adaptive control of electromagnetic waves. This survey explores the principles, progress, and future prospects of Reconfigurable Intelligent Surfaces technology. Topics we address include channel modeling, beamforming optimization, integration with MIMO systems, and applications in mmWave and THz networks. In addition, we examine the potential benefits and limitations of employing AI for RIS optimization and compare RIS to conventional relaying approaches. We conclude by pointing out the upcoming challenges and potential research areas in this rapidly developing research area.