Achieving Covert Wireless Communications Using a Full-Duplex Multi-Antenna Receiver

Covert communication can prevent adversary from knowing the existence of the transmissions while guaranteeing the security in wireless communications. In this paper, interference power uncertainty is exploited to achieve covert communication by using a full-duplex (FD) multi-antenna receiver. Specifically, the receiver first selects the best antenna to receive the covert information from the source, and then utilizes one of the remaining antennas to generate artificial noise with a varying power causing uncertainty at the adversary. We derive the detection limit of adversary, based on which we determine the maximum effective covert rate subject to a given covertness constraint. Our analysis shows that the artificial noise produced deliberately by the FD multi-antenna receiver with a random transmit power offers a positive effective covert rate, and boosting the number of antennas increases the capacity of performing the covert communication.