Network integrity via coordinated motion of stratospheric vehicles

This paper considers the task of deploying mobile wireless repeaters on aerial vehicles in the upper air of Earth to increase the Internet connectivity of users with little to no network infrastructure. By routing data between a user and a strong connection to the Internet through the vehicle network, this ad hoc infrastructure can provide Internet access to those currently without it. We consider two different types of vehicles, altitude-actuating balloons and fixed-altitude gliders, and examine the task of finding optimal vehicle trajectories under lateral wind dynamics employing a throughput-based performance function. Given the complexity of computing the optimal trajectories of all vehicles simultaneously, we introduce an approximation that allows us to determine the optimal trajectory of a single vehicle. We use this optimal trajectory as a reference for the network and develop a coordination algorithm that makes all vehicles follow it while being spaced out equally in time, providing good overall coverage to users. For gliders, we show that, if cost of control is small enough, these vehicles converge to a stationary formation rather than flow with the wind. Simulations validate the throughput performance of the proposed periodic trajectories.