Unmanned Aerial Vehicle aided Batteryless Covert Communications: A Robust Design Against Cooperative Hostile Detection

An unmanned-aerial-vehicle (UAV) is exploited for securely collecting sensing data from massively deployed batteryless devices on the ground. Specifically, signals emitted by the UAV have the following functions: jamming hostile wardens (HWs) and powering legitimate devices (LDs). The transmit power of both the LDs and the UAV as well as the UAV's flying trajectory are jointly optimised for maximising the uplink throughput of data collection, while ensuring that the uplink transmissions of LDs to the UAV cannot be detected by HWs. The formulated optimisation problem is difficult to solve due to its non-convexity. Therefore, a successive convex approximation (SCA) based alternating optimisation (AO) is proposed for obtaining a near-optimal solution. In our design, the UAV does not need the exact locations of the HWs, while it is robust to the optimal cooperative detection among the HWs with a greedy scheduling (GS) based algorithm. The numerical results demonstrate that the uplink-throughput can be substantially improved by our joint design.