Robust Aerial Stealth: Mobility-Aware RIS Beamforming for Anti-Eavesdropping in 6G Networks
摘要
Improving Physical-Layer Security (PLS) is essential for next-generation wireless networks, especially in volatile propagation environments. To address this challenge, this work proposes a mobility-assisted secure transmission framework wherein a Reconfigurable Intelligent Surface (RIS) is integrated directly onto an Unmanned Aerial Vehicle (UAV). By explicitly exploiting the specific impact of integrating UAV spatial mobility with RIS passive beamforming, the proposed architecture enables the on-demand formation of favorable Line-of-Sight (LoS) links with legitimate receivers while simultaneously mitigating information leakage toward potential eavesdroppers. To evaluate system resilience, the average secrecy rate is utilized as the principal metric. A joint optimization problem is formulated that rigorously couples 2D trajectory optimization with altitude selection, transmit power allocation, and RIS phase-shift configuration within a unified design framework. Owing to the problem’s intrinsic non-convexity, a novel and efficient iterative approach leveraging Block Coordinate Descent (BCD) alongside Successive Convex Approximation (SCA) is devised to systematically decouple the variables and ensure fast, stable convergence. Extensive numerical evaluations demonstrate that the proposed UAV-RIS-assisted system achieves a maximum secrecy rate of 11.0 bps/Hz, which is markedly higher than the 4.6 bps/Hz attained by conventional static RIS benchmarks, representing a substantial 139% improvement. These results substantiate the system’s superior robustness against scalable threats, maintaining secure connectivity even under high-density wiretapping scenarios (