Security of Integrated Sensing and Communication Systems with Hybrid Eavesdroppers

In this paper, we consider the joint beamforming design in secure integrated sensing and communication (ISAC) systems, where the active eavesdropper intercepts the transmitted confidential information with an external passive eavesdropper. To improve the sensing performance while preventing the potential eavesdropping, the base station transmits a signal consisting of information symbols and sensing waveform, in which the sensing waveform is also used as artificial noise to interfere with eavesdroppers. Under this setup, we formulate the communication and sensing beamforming design problem, which aims to enhance the transmit beampattern performance, while ensuring the quality of service (QoS) of communication transmission and the secure communication constraint. Furthermore, we propose the semi-definite relaxation (SDR) algorithm to solve the non-convex problem. Numerical results demonstrate the effectiveness of the proposed scheme in both sensing and secure communication.