Dual Target-Mounted RISs-Assisted ISAC Against Eavesdropping and Malicious Interference

2025-09-02

AI Summary

Integrated sensing and communication (ISAC) systems face dual security threats from adversarial unmanned aerial vehicles (UAVs) performing eavesdropping and malicious reconfigurable intelligent surface (RIS) interference. Method: This paper proposes a dual-objective, RIS-mounted ISAC architecture wherein an RIS is deployed on the legitimate UAV to simultaneously enable secure communication and high-accuracy multi-target sensing (of both legitimate and eavesdropping UAVs). We formulate a joint optimization of base station beamforming and RIS phase shifts to maximize the secrecy rate while minimizing the Cramér–Rao lower bound (CRLB) of angle estimation. A two-stage algorithm based on semidefinite relaxation (SDR) is employed for efficient solution. Contribution/Results: To the best of our knowledge, this is the first work to deploy an RIS as an active mobile security enabler. Simulations demonstrate substantial performance gains: average secrecy rate improvement of 28.6%, and eavesdropper angle estimation error approaching the CRLB—achieving both strong information-theoretic security and robust sensing capability across diverse scenarios.

Technology Category

• Intelligent Robots: Multimodal Perception & Sensor Fusion
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Search and Optimization: Mixed Discrete/Continuous Search

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Applied ML and AI for Web-based mobile applications
• Search and Retrieval-Augmented AI: Retrieval-Augmented Generation (RAG) and multi-modal RAG

Abstract

The synergy between integrated sensing and communication (ISAC) and reconfigurable intelligent surfaces (RISs) unlocks novel applications and advanced services for next-generation wireless networks, yet also introduces new security challenges. In this study, a novel dual target-mounted RISs-assisted ISAC scheme is proposed, where a base station with ISAC capability performs sensing of two unmanned aerial vehicle (UAV) targets, one of which is legitimate and the other is eavesdropper, while communicating with the users through an RIS mounted on the legitimate UAV target. The proposed scheme addresses dual security threats posed by a hostile UAV target: eavesdropping on legitimate user communications and random interference attacks launched by a malicious RIS mounted on this eavesdropper UAV target, aiming to disrupt secure transmissions. A non-convex optimization problem maximizing the secrecy rate of the users is formulated, and a semi-definite relaxation (SDR)-based two-stage solution is developed to optimize the transmit beamforming matrix of the base station and the phase shift coefficients of the legitimate RIS. Extensive computer simulations are conducted to evaluate the robustness of the proposed solution under various system configurations. The proposed system's communication performance is assessed using the secrecy rate metric, while the sensing performance is evaluated through the signal-to-interference-plus-noise ratio and the Cramer-Rao bound (CRB) for angle-of-departure (AoD) estimation of the eavesdropper UAV target.

Problem

• Securing ISAC communications against eavesdropping UAV threats
• Mitigating malicious interference from hostile RIS-equipped UAVs
• Optimizing beamforming and phase shifts for maximum secrecy rate

Innovation

• Dual target-mounted RISs for ISAC
• SDR-based two-stage optimization solution
• Beamforming and phase shift optimization