Safeguarding RSMA Networks with Cooperative Jamming and Relaying

Abstract

Cooperative rate-splitting multiple access (C-RSMA) has emerged as a promising solution for increasing spectral efficiency over conventional RSMA. On the other hand, the presence of eavesdroppers seriously compromises secure communications due to the open nature of the wireless channel. In this paper, we study a physical-layer security (PLS) problem for a two-user C-RSMA system in the presence of an eavesdropper. The cooperative jamming and relaying scheme is proposed to enhance diversity and security, where the near user opportunistically generates an artificial noise (AN) and forwards its decoded common message in two transmission phases. Our goal is to maximize the minimum secrecy rate (SR) for both users by the joint design of beamforming and resource allocation. To address the challenges arising from the non-convexity of the problem, we propose a sequential parametric convex approximation (SPCA)-based iterative algorithm, which entails approximating the non-convex objective and constraints by utilizing sequences of convex functions. Moreover, we study two SR maximization problems involving two different partial channel state information cases, and then resolve them by applying two novel SPCA-based iterative algorithms. Simulation results verify the effectiveness of the proposed scheme, demonstrating a significant improvement in SR compared to the schemes without jamming or relaying transmission. © 1967-2012 IEEE.