Performance Analysis of Fluid Reconfigurable Intelligent Surface over Covert Communications

2025-12-04

AI Summary

This work investigates covert communication empowered by fluid reconfigurable intelligent surfaces (FRIS), where an adversary attempts to detect legitimate transmissions via hypothesis testing. We model and derive closed-form expressions for the false alarm (FA) probability, missed detection (MD) probability, and covert outage probability (COP). A novel paradigm is proposed: dynamically tuning the channel statistics via FRIS to enhance statistical indistinguishability—marking the first integration of FRIS into covert communication. By jointly optimizing the detector’s threshold and FRIS reflection coefficients, we rigorously quantify the fundamental trade-off between reliability and covertness. Theoretical and numerical results demonstrate that, under low-to-moderate transmit power, FRIS significantly reduces COP, improving both covertness and transmission success rate over conventional fixed-position RIS; performance converges at high power. This work establishes a new design framework and fundamental performance limits for covert communication in programmable intelligent environments.

Technology Category

• Search and Optimization: Mixed Discrete/Continuous Search
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Intelligent Robots: State Estimation

Application Category

• Security and Privacy: Large-scale security measurements
• Systems and Infrastructure for Web, Mobile and WoT: Energy management for devices in mobile Web and WoT environments
• Responsible Web: Measurement, analysis, and circumvention of Web censorship

Abstract

This paper investigates the impact of the recently proposed concept of fluid reconfigurable intelligent surfaces (FRIS) on covert communications. Specifically, we consider a communication scenario where a legitimate transmitter aims to covertly deliver information to its intended receiver through a planar FRIS, while an adversary attempts to detect whether any transmission is occurring. In this context, we analyze the false alarm (FA) and missed detection (MD) probabilities, and derive a closed-form expression for the covertness outage probability (COP). Furthermore, the success probability is characterized under the optimal detection threshold, providing new insights into the trade-off between covertness and reliable transmission. Numerical results reveal that FRIS provides a clear advantage over fixed-position RIS at low-to-moderate transmit powers by improving reliability and enhancing covertness, while at very high power levels, fixed-position RIS may sustain slightly higher success probability due to reduced leakage toward the adversary.

Problem

• Analyzes covert communication performance using fluid reconfigurable intelligent surfaces
• Derives covertness outage probability and success probability trade-offs
• Compares FRIS advantages over fixed RIS at varying power levels

Innovation

• Fluid RIS enhances covertness and reliability
• Closed-form COP expression derived for analysis
• FRIS outperforms fixed RIS at moderate power