On Performance of FAS-aided Covert Communications

TL;DR

This paper analyzes how fluid antenna systems (FAS) affect covert communication performance, showing that FAS at the warden improves detection, while FAS at the receiver enhances transmission reliability.

Contribution

It provides analytical expressions for covertness outage probability in FAS-aided covert communications and compares FAS with fixed antennas, revealing their impact on detection and transmission success.

Findings

FAS at the warden increases detection capability.

FAS at the receiver improves reception quality.

Optimal detection threshold maximizes covertness outage probability.

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.