Joint Deployment and Trajectory Planning of Multiple UAVs for Emergency Communications

In this paper, we study the unmanned aerial vehicle (UAV)-assisted emergency communication network, where multiple UAVs are dispatched from emergency centers and cruise the target region to provide service. To ensure timely communications, a strict requirement is that the time spent on the tour of each UAV is no greater than a delay threshold. Our optimization task is to minimize the total cost while satisfying the delay constraints, in which the total cost is a weighted sum of deployment cost and cruise cost. We propose a joint deployment and path planning scheme to address the NP-hard task from a load-balancing perspective. Specifically, we first adopt a continuous approximation method to estimate the number of needed emergency centers and locate them by clustering. Then, we assign the ground users to the emergency centers via loadbalancing region partitioning, based on which the path planning of multiple UAVs can be reduced to independent traveling salesman problems. Numerical results demonstrate that our proposal can complete the delay-bounded mission at the lowest cost as compared with other methods, providing an efficient and cost-effective way for practical emergency communications.