UAV Deployment and IoT Device Association for Energy-Efficient Data-Gathering in Fixed-Wing Multi-UAV Networks

This work studies the deployment of multiple fixed-wing unmanned aerial vehicles (UAVs) for data-gathering from ground IoT devices and the corresponding device association policy. Each UAV is assumed to follow a circular flight trajectory above its responsible network area in order to stay afloat. The device association and the UAVs’ trajectory centers and radii are jointly optimized to maximize the total energy savings of the devices. Given the trajectory centers and radii, the device association problem is modeled as a multiple 0–1 knapsack problem, and solved by a two-stage maximum energy-saving (MES) device association policy. Moreover, given the device association, the UAVs’ trajectory centers and radii are optimized by an iterative load-balancing (ILB) algorithm, where the trajectory centers are chosen as a load-dependent weighted sum of their associated devices’ locations. Furthermore, we also propose a collision-free scheduling policy that minimizes the total phase offset between the actual and ideal transmission phases of all devices, and a modified MES algorithm that provides higher association priority to devices whose data gathered by the UAV is more outdated. Simulation results show that the proposed MES and ILB algorithms outperform candidate schemes in terms of the total energy savings of IoT devices.