Beamforming Design for Secure Wireless Sensing in ISAC Systems

Integrated sensing and communication (ISAC) has been identified as one of the six typical usage scenarios for sixth-generation (6G) mobile communications. In this paper, we study beamforming design for secure ISAC systems to prevent sensing information leakage to potential sensing eavesdroppers. To obtain a good beamforming design, we consider the impacts of ISAC echo signals reflected from target on communication users, and formulate the optimization problem of maximizing the sensing signal-to-noise ratio (SNR) while ensuring that the communication signal-to-interference-plus-noise ratio (SINR) is not less than a certain threshold and the sensing eavesdropping SNR is not larger than a certain threshold. To solve this non-convex optimization problem, we develop a Riemannian manifold-based conjugate gradient algorithm. Finally, to demonstrate the effectiveness of the proposed algorithms, simulations are conducted. The simulation results demonstrate that the proposed method can reduce the detection probabilities of sensing eavesdroppers. The results also reveal that there are trade-offs between secure sensing performance, communication performance, and sensing eavesdropping suppression.