Secure Waveform Design for MIMO Integrated Sensing and Communication Under the Stochastic TIR Model

To address the challenges of ensuring communication security for legitimate users in the presence of eavesdroppers and the limited detection performance for extended targets in an Integrated Sensing and Communication (ISAC) system, this paper proposes a secure waveform design method for a multi-input multi-output (MIMO) ISAC system, under a stochastic Target Impulse Response (TIR) model. Firstly, To prevent confidential information in ISAC systems from being intercepted by unauthorized users, transmit waveforms and artificial noise(AN) are designed to maximize the sum secrecy rate of all communication users while ensuring individual user quality of service. Secondly, recognizing that accurate TIR information is unavailable in the practical detection environment, the stochastic TIR model is established under the assumption that prior errors follow a complex Gaussian distribution, and the robust detection probability of the extended target under the stochastic TIR is employed as a constraint to ensure the system’s detection performance. To solve this non-convex mixed max-min fractional programming(FP) problem, the Decomposition-Based Large Deviation Inequality (DBLDI) is adopted to convert the robust detection probability constraint into a convex constraint. By incorporating quadratic transform, inverse quadratic transform, and Lagrangian Dual Transform, a FP solution approach is developed to convert the mixed max-min FP problem into a convex problem. Finally, semidefinite optimization and alternating optimization methods are employed to iteratively optimize the transmit waveform, AN, and the receive filter. Additionally, the convergence and complexity analysis of the proposed method are provided. Simulation results demonstrate that the proposed method can guarantee the communication security of multiple legitimate users in the presence of multiple eavesdroppers. Meanwhile, it can also meet the stable detection requirements of extended targets, and the solution speed is nearly twice higher compared with the BTI method.