Partial Relay Selection for Covert Communication in Two-Hop Relay Systems

Abstract

This paper investigates the impact of relay selection on covert communication performance in a two-hop wireless relay system, where a transmitter intends to transmit messages to a receiver via a selected relay, subjecting to detection from a warden. To this end, we first propose a partial relay selection scheme based on the signal-to-interference-plus-noise-ratio (SINR) at the relay. We then provide theoretical models for the detection error probability, transmission outage probability, and covert rate. We further explore the optimal designs of the transmit power and target transmission rate for the covert rate, subjecting to the constraints of covertness and the upper bound of transmit power. Finally, we provide extensive numerical results to illustrate the covert rate performance via the partial relay selection scheme in a two-hop relay system.