Reconfigurable Intelligent Surface–Aided Physical-Layer Security for 6G Networks
Shen Qian
Abstract
Physical-layer security (PLS) is increasingly considered as a complementary protection layer for beyond-5G and 6G systems, where dense device deployments and stringent latency/energy constraints can increase the overhead of purely upper-layer cryptographic protection. Reconfigurable intelligent surfaces (RISs) offer a low-power means to reshape radio propagation and create channel advantages for legitimate users, potentially enhancing PLS. This paper provides an application-oriented overview of RIS-aided PLS in 6G networks. We first revisit the fundamental concepts of PLS, including secrecy capacity, wiretap-channel and fading-channel models, and classical techniques such as beamforming and artificial noise. We then summarize the role of RIS in 6G architectures and review how RIS can be integrated into single-user, multi-user, and cooperative networks, with particular attention to untrusted relay and IoT scenarios. A taxonomy is proposed to classify representative RIS-aided PLS schemes according to system model, threat model, design methodology, and processing architecture. Finally, we discuss how learning tools—DRL for sequential decision-making, GNNs for topology aware representations, and FL for privacy-preserving distributed training—can be combined with RIS-assisted PLS to cope with the scale and dynamics expected in 6G deployments.