Win-Win of Communication and Sensing Security for MC-NOMA ISAC Systems

In this paper, we focus on both the communication and sensing security in the proposed multiple-subcarrier (MC) non-orthogonal multiple access (NOMA)-assisted integrated sensing and communication (ISAC) systems, where an active eaves-dropper is considered with imperfect channel state information (CSI). We consider a secure ISAC design by adopting the proposed secrecy rate and secrecy Cramér-Rao bound (S-CRB) metrics under the bounded CSI errors model. The joint design of artificial noise (AN) and dual-functional radar communications (DFRC) signals beamforming as well as subcarrier allocation is formulated to maximize the minimum achievable rate, while ensuring the hierarchical confidentiality requirements for users and satisfying the leakage CRB constraint for the target. To handle the non-convex problem, we devise a low-complexity successive convex approximation (SCA)-based suboptimal algorithm, and its ε-optimality is validated via our proposed branch and bound (B&B) algorithm in simulations. Numerical results reveal the effectiveness and superiority of our proposed scheme compared to the other baselines. Moreover, the inherent win-win relationship between the sum secrecy rate and target S-CRB is demonstrated via various simulation results, which provides several insights into secure MC-NOMA ISAC network deployment.