On Stochastic Performance Analysis of Secure Integrated Sensing and Communication Networks
Marziyeh Soltani, Mahtab Mirmohseni, Rahim Tafazolli
TL;DR
This work analyzes the stochastic security performance of a downlink MIMO ISAC system facing both a communication eavesdropper and a sensing eavesdropper under Rayleigh fading. It introduces an artificial-noise aided transmit structure and derives exact expressions for the secrecy ergodic rate $C_s=(E[R]-E[R_e])^+$ and the ergodic CRBs $E[\text{CRB}(\theta)]$ and $E[\text{CRB}(\phi)]$, treating the CRB as a random variable and employing CLT-based PDFs for tractability. The CRB analysis yields closed-form and bounded expressions for the CCDFs $P(\text{CRB}(\theta) > \epsilon)$ and $P(\text{CRB}(\phi) > \epsilon)$, along with exact ergodic CRBs and their common-approximation bounds, enabling precise evaluation of target localization privacy in stochastic ISAC networks. Numerical results corroborate the theory, showing positive secrecy rates for a range of power allocations and illustrating the distinct behavior of CRBs for the BS and the sensing eavesdropper, thereby highlighting the impact of AN-based beamforming on ISAC security and privacy.
Abstract
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 angular location, and counteract eavesdropping threats. The system includes a passive single-antenna communication eavesdropper and a multi-antenna sensing eavesdropper attempting to infer the target location. The BS-user and BS-eavesdroppers channels follow Rayleigh fading, while the target azimuth angle is uniformly distributed. To evaluate the performance, we derive exact expressions for the secrecy ergodic rate 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. Numerical results validate our findings.
