Secure Beamforming for RIS-Aided ISAC System With CRB Minimization

Since the security is an important issue in integrated sensing and communications (ISAC), especially when the targets also act as potential eavesdroppers, we investigate the secure beamforming design for the reconfigurable intelligent surface (RIS)-aided ISAC system. Aiming at minimizing the worst-case Cramér–Rao bound of the two-dimensional direction-of-arrival estimation of the eavesdropper, we consider the joint design of transmit beamforming and RIS phase shifts subject to the constraints of signal-to-interference-plus-noise ratio (SINR) of each user and the worst-case eavesdropping SINR. To solve this joint optimization problem, we propose an algorithm based on penalty dual decomposition. Numerical results demonstrate the effectiveness of the proposed algorithm.