Covert Communications in Two-way Relay Systems with Energy Harvesting

This paper investigates the covert communications in the wireless-powered two-way relay systems with energy harvesting. The primary task of the relay is to assist the source nodes on both sides in completing the legitimate communication. Based on this, relay attempt to transmit covert information to source nodes. With limited transmit power at the relay, a reliable transmission strategy is needed to against the warden, who detects whether the relay transmits the cover message or not. We first analyzed the detection error probability at the warden. Based on the detection performance of the warden, we propose a ratio-control transmit strategy for the relay, which can efficiently implement covert communication with the harvested energy while the warden has optimized the detection error probability.