Physical Layer Security over Fluid Reconfigurable Intelligent Surface-assisted Communication Systems

2025-09-29

AI Summary

This work addresses physical-layer security in fluid reconfigurable intelligent surface (FRIS)-assisted wireless communication systems under eavesdropping threats. Method: We propose a dynamic selective activation mechanism for FRIS reflection units, enabling adaptive spatial diversity and channel customization under spatially correlated fading channels—overcoming the limitations of conventional RISs with fixed structures and static responses. A rigorous FRIS-aided coexistence channel model incorporating both legitimate users and eavesdroppers is established. Tight analytical upper and lower bounds on the secrecy outage probability and average secrecy capacity are derived. Results: Numerical results demonstrate that even with partial unit activation, FRIS significantly outperforms conventional RIS across varying deployment densities and spatial correlation levels—substantially reducing outage probability and enhancing average secrecy capacity. This validates FRIS’s superior security gains in dynamic wireless environments.

Technology Category

• Intelligent Robots: Multi-Robot Systems
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Machine Learning: Privacy

Application Category

• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Web evaluation methodologies and metrics
• User Modeling, Personalization and Recommendation: Attacks and countermeasures in recommendation systems

Abstract

This letter investigates the secrecy performance of wireless communication systems assisted by a fluid reconfigurable intelligent surface (FRIS). Unlike conventional reconfigurable intelligent surfaces (RISs) with fixed geometries, FRISs dynamically select a subset of reflective elements based on real-time channel conditions, offering enhanced spatial diversity and adaptability. Using this foundation, we model a secure downlink scenario where a base station communicates with a legitimate user in the presence of an eavesdropper, and the propagation is assisted by a FRIS with a limited number of elements set to the ON state. We analyze the system's secrecy performance under spatial correlation by deriving analytical lower and upper bounds for the secrecy outage probability (SOP) and average secrecy capacity (ASC), respectively. Our results demonstrate that FRIS effectively enables secure communication under spatial correlation. Even with partial activation, FRIS significantly outperforms conventional RISs in enhancing secrecy performance under varying deployment densities and element correlations.

Problem

• Analyzing secrecy performance of fluid RIS-assisted wireless communication
• Modeling secure downlink with eavesdropper under spatial correlation
• Comparing fluid RIS with conventional RIS for enhanced security

Innovation

• FRIS dynamically selects reflective elements adaptively
• Analytical bounds derived for secrecy outage probability
• Partial activation FRIS outperforms conventional RIS significantly