Detection Error Probability Maximization for Disguised Full-Duplex Covert Communications

This paper delves into reliable covert communications with a disguised full-duplex (FD) node. Seemingly half-duplex receive-only, this node in our considered system simultaneously listens to a transmitter and secretly transmits covert mes- sages to another hidden receiver. In the meantime, a warden attempts to detect this covert link. We first study the detection error probability (DEP) and identify the minimum DEP from the perspective of the warden. After that, we derive the optimal transmit power of the disguised FD node that concurrently maximizes the minimum DEP and guarantees a given reliability of the covert rate. Numerical results validate the effectiveness of our proposed solution and present how dif- ferent system parameters affect DEP performance. In conclusion, we provide valuable guidance for the design of secure communication systems and suggest future research directions in this critical domain.