This paper analyzes the stochastic security performance of a multiple-input multiple-output (MIMO) integrated sensing and communication (ISAC) system in a downlink scenario. A base station (BS) transmits a multi-functional signal to simultaneously communicate with a user, sense a target's angular location, and counteract eavesdropping threats. The attack model considers a passive single-antenna communication eavesdropper intercepting communication data, as well as a multi-antenna sensing eavesdropper attempting to infer the target's location. We also consider a malicious target scenario where the target plays the role of the communication eavesdropper. The BS-user and BS-eavesdroppers channels follow Rayleigh fading, while the target's azimuth angle is uniformly distributed. To evaluate the performance in this random network, we derive the ergodic secrecy rate (ESR) and the ergodic Cramer-Rao lower bound (CRB), for target localization, at both the BS and the sensing eavesdropper. This involves computing the probability density functions (PDFs) of the signal-to-noise ratio (SNR) and CRB, leveraging the central limit theorem for tractability. We characterize the boundary of the CRB-secrecy rate region, and interpret the performance tradeoffs between communication and sensing while guaranteeing a level of security and privacy in the random ISAC networks.

翻译：本文分析了多输入多输出集成感知与通信系统在下行链路场景中的随机安全性能。基站通过发射多功能信号，同时与用户通信、感知目标角度位置并应对窃听威胁。攻击模型考虑了一个被动的单天线通信窃听者拦截通信数据，以及一个多天线感知窃听者试图推断目标位置。我们还考虑了恶意目标场景，其中目标充当通信窃听者。基站-用户和基站-窃听者信道遵循瑞利衰落，而目标的方位角服从均匀分布。为评估该随机网络的性能，我们推导了基站和感知窃听者两端用于目标定位的遍历保密速率和遍历克拉美-罗下界。这涉及计算信噪比和CRB的概率密度函数，并利用中心极限定理以保证可处理性。我们刻画了CRB-保密速率区域的边界，并阐释了在保证随机ISAC网络一定安全与隐私水平的前提下，通信与感知之间的性能权衡。