Reconfigurable Intelligent Surface-Aided Multi-User Networks: Interplay Between NOMA and RIS

This article focuses on the exploitation of reconfigurable intelligent surfaces (RISs) in multiuser networks employing orthogonal multiple access (OMA) or non-orthogonal (NOMA), with an emphasis investigating interplay between NOMA and RIS. Depending whether RIS reflection coefficients can be adjusted only once times during one transmission, we distinguish static dynamic configurations. In particular, capacity region RIS-aided single-antenna is discussed compared OMA rate from information-theoretic perspective, revealing that configuration capacity-achieving. Then, impact deployment location performance different schemes investigated, which reveals asymmetric symmetric strategies are preferable for OMA, respectively. Furthermore, multiple-antenna networks, three novel joint active passive beamformer designs proposed based both beamformer-based cluster-based strategies. Finally, open research problems RIS-NOMA highlighted.