RIS-Mounted UAV Enhanced Wireless Secrecy with Covert Transmission Constraint

This paper investigates a reconfigurable intelligent surface (RIS) mounted unmanned aerial vehicle (UAV) assist wireless communication networks for achieving both information security and transmission covertness wireless networks. To address the dual challenges of eavesdropping by the untrusted user and transmission detection by the hostile warden Willie, we propose an optimization framework that co-designs the Alice transmit power, RIS reflecting phase-shifts and UAV trajectory. Specifically, the optimization problem is formulated to maximize the average achievable secrecy rate with covertness constraint. Then, we introduce variable slackness and successive convex approximation (SCA) approaches, so as to convert the initial nonconvex problem into three solvable subproblems. Furthermore, we propose and summarize an optimization algorithm to solve these subproblems alternatively. Finally, simulation results verify the effectiveness of our proposed RIS-UAV enhanced wireless secure and covert communication systems.