Achieving Covert Wireless Communications Using a Full-Duplex Receiver

TL;DR

This paper proposes a covert wireless communication method using a full-duplex receiver that generates artificial noise to obscure transmission from an adversary, deriving optimal detection performance and guidelines for parameter selection.

Contribution

It introduces a novel covert communication scheme with a full-duplex receiver that optimizes artificial noise and transmission probability for maximum covertness under fading channels.

Findings

Artificial noise enhances covertness despite self-interference.

Optimal artificial noise power range improves detection error at adversary.

Prior transmission probability of 0.5 is not always optimal for covertness.

Abstract

Covert communications hide the transmission of a message from a watchful adversary while ensuring a certain decoding performance at the receiver. In this work, a wireless communication system under fading channels is considered where covertness is achieved by using a full-duplex (FD) receiver. More precisely, the receiver of covert information generates artificial noise with a varying power causing uncertainty at the adversary, Willie, regarding the statistics of the received signals. Given that Willie's optimal detector is a threshold test on the received power, we derive a closed-form expression for the optimal detection performance of Willie averaged over the fading channel realizations. Furthermore, we provide guidelines for the optimal choice of artificial noise power range, and the optimal transmission probability of covert information to maximize the detection errors at Willie. Our analysis shows that the transmission of artificial noise, although causes self-interference, provides the opportunity of achieving covertness but its transmit power levels need to be managed carefully. We also demonstrate that the prior transmission probability of 0.5 is not always the best choice for achieving the maximum possible covertness, when the covert transmission probability and artificial noise power can be jointly optimized.