Jamming-Enhanced Secure UAV Communications With Propulsion Energy and Curvature Radius Constraints

A multi-unmanned aerial vehicles (UAVs)-aided secure communication network is studied, where multiple information UAVs carrying temporary aerial base stations transmit confidential information to multiple authorized receivers (ARs), and a jammer UAV is employed to send artificial noise to multiple unauthorized receivers (URs) for mitigating information leakage. Some practical constrains including the inter-UAV interference among the information UAVs and the jammer UAV, the maximal available propulsion energy at UAVs, and the curvature radius limitations of UAVs' trajectories are concurrently taken into account. In order to maximize the minimum secrecy rate among the ARs, the AR scheduling, the UAVs' power allocation and the trajectories of UAVs are jointly optimized by formulating a multi-variable optimization problem. To solve the non-convex problem efficiently, we present a block coordinate descent (BCD)-based approach, where the penalty dual decomposition (PDD)-based algorithm is designed to optimize the AR scheduling, and successive convex approximation (SCA)-based algorithm is proposed to optimize the UAVs' power allocation and the trajectories of UAVs. The complexity of the presented BCD-based approach is analyzed, which achieves polynomial complexity. Simulation results show that imposing curvature radius limitations on the UAVs' trajectory design is effective to avoid sharp turning of UAVs. Moreover, as curvature radius increases, the system max-min secrecy rate decreases. Besides, the secrecy rate performance of the system can be enhanced by exploiting one jammer UAV to interfere with the URs.