Sum Secrecy Rate Optimization for Active RIS Aided Uplink NOMA-ISAC Systems

This letter studies a secure uplink non-orthogonal multiple access integrated sensing and communication (NOMA-ISAC) system, and propose an active reconfigurable intelligent surface (ARIS)-aided NOMA-ISAC scheme, where multiple users transmit information to the base station (BS) with the aid of ARIS. Simultaneously, the BS detects potential eavesdroppers (Eves) while receiving user signals, and mitigates the interference between sensing signals and communication signals through successive interference cancellation (SIC). Notably, we consider the BS cannot obtain perfect angular information of the target. To maximize sum secrecy rate (SSR) of the proposed scheme while satisfying the sensing performance, we formulate a joint optimization problem involving receive and transmit beamforming at the BS, the ARIS reflection matrix, and the users’ transmit powers. To address this non-convex problem, we further develop a successive convex approximation (SCA)-based algorithmic framework. Numerical results demonstrate that the proposed scheme comprehensively outperforms all benchmark methods in terms of SSR performance while satisfying the sensing SINR threshold constraints.