Relay-Assisted ISAC Networks: Secrecy, Reliability, and Detection Insights

Integrated sensing and communication (ISAC) is transforming how wireless resources are designed and utilized, but it introduces new privacy and security threats. This paper examines a cooperative relay-assisted ISAC network under Rayleigh fading with eavesdropping threats. To facilitate performance analysis, we developed a unified framework that characterises both communication and sensing reliability by deriving closed-form expressions for outage probability (OP) and communication secrecy outage probability (CSOP), probability of detection (PoD), and probability of false alarm (PoFA). The framework jointly captures antenna diversity, relay operation, and noise effects. Monte Carlo simulations validate the analysis and illustrate key trade-offs among secrecy, communication reliability, and sensing accuracy. Results show that cooperative relaying with multiple antennas significantly improves security–reliability performance, while detection accuracy is highly sensitive to noise variance and sensing thresholds. The findings provide design guidelines for relay-assisted ISAC systems in practical 6G scenarios.