UAV-Enabled Covert and Secure Communication Against Cooperative Detection and Eavesdropping

Unmanned aerial vehicle (UAV)-enabled wireless communication technique has emerged as a promising paradigm in the next generation communication networks. However, due to the security issues arising from the inherently open nature of air to ground (A2G) links, the security of both communication behavior and information faces significant threat. To address this issue, we investigate a UAV-enabled covert and secure communication network against cooperative detection and eavesdropping from multiple illegal eves, which can share the intercepted signals with others. Specifically, from the perspective of secure communication considering channel uncertainty and cooperative eavesdropping, we characterize users' upload secure throughput by an ergodic integral expression, and formulate a max-min throughput optimization problem through joint design of UAV trajectory, user transmit power and segmentation ratio, under mobility, energy consumption and covertness constraints. Then, to address the problem with complicated covertness metric with no closed-form expression under cooperative detection, we derived closed form expressions of the covertness metric, by utilizing the Pinsker inequality along with properties of both Taylor series and the Digamma function. Subsequently, the monotonicity of the derived metric is analyzed and further utilized to simplify the covertness constraint into transmit power constraint equivalently. Afterward, a novel convex approximation method is introduced to construct a convex subproblem for the formulated highly complicated non-convex problem, enabling an efficient algorithm that delivers high-quality solutions for the formulated problem. Finally, the effectiveness and superior performance of proposed design are verified through simulations.