wireless communications

mac protocol

channel model

reconfigurable intelligent

wireless communication

intelligent reflecting

millimeter wave

intelligent surface

IEEE Communications Magazine

Recent advances in the fabrication and experimentation of Reconfigurable\nIntelligent Surfaces (RISs) have motivated the concept of the smart radio\nenvironment, according to which the propagation of information-bearing\nwaveforms in the wireless medium is amenable to programmability. Although the\nvast majority of recent experimental research on RIS-empowered wireless\ncommunications gravitates around narrowband beamforming in quasi-free space,\nRISs are foreseen to revolutionize wideband wireless connectivity in dense\nurban as well as indoor scenarios, which are usually characterized as strongly\nreverberant environments exhibiting severe multipath conditions. In this\narticle, capitalizing on recent physics-driven experimental explorations of\nRIS-empowered wave propagation control in complex scattering cavities, we\nidentify the potential of the spatiotemporal control offered by RISs to boost\nwireless communications in rich scattering channels via two case studies.\nFirst, an RIS is deployed to shape the multipath channel impulse response,\nwhich is shown to enable higher achievable communication rates. Second, the\nRIS-tunable propagation environment is leveraged as an analog multiplexer to\nlocalize non-cooperative objects using wave fingerprints, even when they are\noutside the line of sight. Future research challenges and opportunities in the\nalgorithmic design and experimentation of smart rich scattering wireless\nenvironments enabled by RISs for sixth Generation (6G) wireless communications\nare discussed.\n

Reconfigurable Intelligent Surfaces for Rich Scattering Wireless Communications: Recent Experiments, Challenges, and Opportunities