Reconfigurable Intelligent Surface Aided Multi-User Communications: State-of-the-Art Techniques and Open Issues

• Published in: IEEE access 2021, Vol.9, p.118584-118605
• Main Authors: Munochiveyi, Munyaradzi, Pogaku, Arjun Chakravarthi, Do, Dinh-Thuan, Le, Anh-Tu, Voznak, Miroslav, Nguyen, Nhan Duc
• Format: Article
• Language: English
• Subjects: Array signal processing; Art techniques; cell-free massive MIMO; Cognitive radio; cognitive radio (CR); Communication; Communication system security; Communications systems; Energy consumption; Light fidelity; light fidelity (LiFi); massive antenna; Millimeter waves; mmWave and~THz communications; NOMA; Nonorthogonal multiple access; physical layer security (PLS); Power transfer; rate-splitting multiple access (RSMA); Receivers; Reconfigurable intelligent surface; Reconfigurable intelligent surfaces; Signal processing; simultaneous wireless information and power transfer (SWIPT); State-of-the-art reviews; UAV communications; Unmanned aerial vehicles; Wireless communications; Wireless networks
• ISSN: 2169-3536; 2169-3536
• DOI: 10.1109/ACCESS.2021.3107316

Reconfigurable intelligent surface (RIS)-aided communication is considered as an exciting research topic in academic and industrial communities since it provides an emerging affordable solution to achieve high quality and secure next-generation wireless systems. Especially, the deployment of RIS in multi-user wireless networks promises to reduce system hardware costs, signal processing complexity, as well as energy consumption due to small size, lightweight and ability to actively shape the wireless propagation environment. Further, by realizing a cost-effective radio environment, RIS-aided communication can be implemented to be an appealing technology for future integration with other emerging wireless applications and communication systems. Despite the positive appeal, RISs face new challenges that hinder integrating efficiently into wireless networks, such as network secrecy performance and system sum-rates, as well as achieving efficient deployment design in highly dynamic and time-varying wireless environments. To this end, we overview recent state-of-the-art techniques to address the above issues faced in the integration of RISs with various emerging multi-user communication techniques, such as Unmanned Aerial Vehicles (UAVs), Non-Orthogonal Multiple Access (NOMA), Millimeter Wave (mmWave) and Terahertz (THz) communications, Physical Layer Security (PLS), massive antennas, and Simultaneous Wireless Information and Power Transfer (SWIPT). Finally, we highlight promising future research directions of RIS-aided communication in Cell-Free Massive Multiple-Input-Multiple-Output (MIMO) systems, Rate-Splitting Multiple Access (RSMA), Light Fidelity (LiFi), and Cognitive Radio (CR) systems.