Optimization Algorithm for Maximizing Secrecy Rate in RIS-Assisted ISAC Systems

This study introduces an innovative joint waveform design and precoding strategy leveraging a Reconfigurable Intelligent Surfaces (RIS) and artificial noise (AN) covariance matrix to strengthen physical layer security (PLS) in Integrated Sensing and Communication (ISAC) systems. Considering a realistic communication scenario where the eavesdropper is located closer to the base station and RIS compared to the legitimate user, we formulate a Secrecy Rate (SR) maximization problem under the constraints of ISAC-BS power limits, point target detection threshold, and the unit modulus limitation at RIS. Finally, an efficient alternating optimization (AO) algorithm based on Semidefinite Relaxation (SDR) is employed to resolve the issue of high coupling among variables in the formulated problem.