Full-Duplex Covert Communications Assisted by Intelligent Reflective Surfaces

The letter proposes resource allocation in uplink covert communication systems, which aim to hide the existence of the covert user from the warden. The wireless system consists of a full-duplex receiver, an intelligent reflective surface (IRS), a public user, a covert user, and a watchful warden. The receiver sets the IRS reflection matrix so as to maximize the downlink throughput to the public user. In doing so, in each transmission block we optimize the covert user's transmit power and rate, subject to the detection error probability at the warden and predefined interference level at the public user. The numerical results unveil the importance of increasing the number of reflecting elements at the IRS.