Multi-antenna Covert Communications in Random Wireless Networks with Full-duplex Relay

Covert communication, which protects the existence of wireless transmissions from being detected by a warden, has become a prominent way to ensure wireless communication security. This paper considers a covert communication system, in which a multiantenna transmitter sends the covert message to a single-antenna receiver via a full-duplex (FD) relay in the presence of multiple randomly located wardens and jammers. To depict the covertness performance of the system, we first provide theoretical model for average detection probability and covert outage probability. We further analyze the worst-case situation where wardens maximize the covert outage probability and derive the optimal detection threshold of wardens. Finally, numerical results are provided to evaluate the performance of the covert communication system.