Joint Analog Beamforming and Jamming Optimization for Covert Millimeter Wave Communications

This paper studies covert millimeter-wave (mmWave) communications, where a multi-antenna transmitter (Alice) sends information signals to a full-duplex receiver (Bob) covertly, in the presence of a warden (Willie). For covering the communication by Alice, Bob operates in full-duplex mode which generates jamming signals with a transmit power varying across different time slots. Assuming that Willie adopts a radiometer as its detector, we first derive the optimal detection threshold for Willie. Next, we jointly design the analog beamforming at Alice and the analog jamming at Bob for maximizing the covert rate taking into account the use of optimal detecting at Willie and the communication outage probability experienced by Bob. Although the joint design is nonconvex that is challenging to solve directly, a successive convex approximation algorithm-based algorithm is developed to address the design problem. Simulation results validate the efficiency of the proposed algorithm, compared to some baseline scheme.