RIS and Cooperative Jammer Enhanced Covert Communication

Communication security is of paramount importance, where covert communication serves as a vital means to ensure it. This paper investigates the security performance optimization of a covert communication system assisted by cooperative jamming and a reconfigurable intelligent surface (RIS), aiming to enhance the covert transmission rate. Specifically, we analytically derive the warden's expected detection error probability(DEP) and identify the worst-case warden location that minimizes detection error. Building on this worst-case analysis, we formulate a joint optimization problem to maximize the covert transmission rate by coordinating the transmit power, jamming power, and RIS phase shifts. Numerical results quantify that the warden's location uncertainty leads to a covert rate degradation of approximately 10%, which can be effectively mitigated by the proposed robust optimization strategy.