Joint Sensing and Secure Communication Based on STAR-RIS

This paper proposes a simultaneously transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) enabled scheme for a secure Integrated Sensing and Communications (ISAC) system. In this considered system, the base station (BS) communicates with common users (CUs) and security users (Bobs) while keeping sensing and suppressing potential eavesdropppers. An optimization problem is formulated with the aim of maximizing the energy efficiency of the overall communication system while ensuring the sense requirement for eavesdroppper and satisfying the total transmit powers. To handle the non-convex fractional problem, we propose an iterative quadratic-transform-Dinkelbach method, where semidefinite relaxation (SDR) and successive convex approximation (SCA) techniques are leveraged to solve subproblems. Simulation results indicate the effectiveness of the proposed STAR-RIS-aided scheme compared with the baseline schemes.