Fairness-Aware Secure Communication in ISAC Systems with STAR-RIS and RSMA

TL;DR

This paper explores integrating STAR-RIS and RSMA in ISAC systems to enhance physical layer security, proposing a joint optimization approach for beamforming and RIS coefficients to ensure fairness and improve secrecy rates.

Contribution

It introduces a novel joint optimization framework for secure and fair communication in ISAC systems using STAR-RIS and RSMA, with an efficient algorithm for non-convex problem solving.

Findings

The proposed algorithm converges quickly.

Significant improvements in secrecy rate performance.

Enhanced fairness among users.

Abstract

In this paper, we investigate the integration of simultaneously transmitting and reflecting reconfigurable intelligent surfaces (STAR-RIS) with rate-splitting multiple access (RSMA) for improving physical layer security (PLS) in integrated sensing and communication (ISAC) systems. Specifically, we consider a multi-user, multi-sensing target scenario, where each sensing target is treated as a potential eavesdropper, reflecting realistic deployment conditions. To enable fairness-aware secure communication among users while maintaining sensing performance, we formulate a joint optimization problem that designs the base station beamforming vectors and STAR-RIS coefficients, aiming to maximize the minimum secrecy rate under a minimum beampattern gain constraint. To solve the resulting non-convex problem, we propose an efficient algorithm based on alternating optimization (AO) and the majorization-minimization (MM) method. Simulation results verify the fast convergence of the proposed algorithm and demonstrate significant improvements in secure communication performance.