Joint Transmit and Receive Beamforming Design for Secure Communications in ISAC Systems with Eavesdropper and Jammer

We investigate a secure scheme to protect multi-user downlink communications against eavesdropper and jammer in integrated sensing and communication (ISAC) systems. In this scheme, the ISAC base station (BS) transmits an ISAC waveform to serve communication users and sense target, where the sensing signals can be treated as artificial noise to interfere the eaves-dropper so as to ensure transmission secrecy. Subsequently, an optimization problem is formulated with the aim of maximizing the secrecy sum rate while satisfying the constraints related to the signal-to-interference-plus-noise ratio (SINR) requirements of the received sensing signals as well as the system power budget for transmission, through jointly optimizing the radar recieve filter and the BS's transmit beamforming matrix. Considering the non-convexity of the formulated optimization problem, we propose an alternating optimization algorithm based on the block coordinate descent and the semi-definite relaxation methods to solve this problem. Eventually, upon the simulation analysis, it is demonstrated that the performance achieved by the proposed scheme can significantly enhance the system's sum secrecy rate especially in comparison with the benchmarks.