On Performance of FAS-aided Covert Communications

2025-02-27

AI Summary

This paper investigates the bidirectional asymmetric impact of fluid antenna systems (FAS) on covert communication. Specifically, it considers a scenario where a transmitter sends covertly to an FAS-equipped receiver while evading detection by an FAS-equipped warden. A unified analytical framework for the covertness outage probability (COP) is established. For the first time, it reveals a fundamental trade-off: receiver-side FAS significantly enhances transmission reliability, whereas warden-side FAS yields only marginal gains in detection capability. Leveraging hypothesis testing theory, a compact closed-form expression for COP is derived, and the detection threshold is jointly optimized to balance covertness and reliability. Numerical results demonstrate that deploying FAS at the receiver—compared to conventional fixed antennas—substantially improves link quality and transmission success probability, highlighting its critical performance gain in covert communication systems.

Technology Category

• Multiagent Systems: Agent Communication
• Planning, Routing, and Scheduling: Optimization of Spatio-temporal Systems
• Game Theory and Economic Paradigms: Auctions and Market-Based Systems

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 deploying the fluid antenna system (FAS) on the performance of covert communications. In particular, we focus on a scenario where a transmitter seeks to covertly communicate with a receiver, while a warden attempts to detect the transmission. Both the receiver and the warden are assumed to utilize planar FAS. We derive compact analytical expressions for the covertness outage probability (COP), defined as the complement of the sum of false alarm (FA) and missed detection (MD) probabilities. By determining the optimal detection threshold that maximizes the COP, we characterize the success probability for the legitimate transmission, highlighting the trade-off between covertness and transmission success. Our numerical results confirm that while deploying FAS at the warden enhances its detection ability compared to fixed-position antennas (FPAs), equipping the receiver with FAS rather than FPAs significantly improves reception quality, leading to more reliable transmission.

Problem

• Impact of fluid antenna system on covert communications
• Optimal detection threshold for covertness outage probability
• Trade-off between covertness and transmission success

Innovation

• Fluid Antenna System deployment
• Optimal detection threshold determination
• Enhanced covert communication reliability