Positioning aerial relays to maintain connectivity during drone team missions

Abstract

Approaches that aim to maintain the connectivity of unmanned aerial vehicles (UAVs) or drones either utilize cellular networks or propose to jointly optimize connectivity needs with other mission tasks. Therefore, most solutions either rely on existing infrastructure or are optimized for specific applications. Use of UAVs to assist the connectivity of ground nodes is commonly proposed. In this work, we deploy UAVs as relays to support mission-oriented UAV networks in order to decouple the mission and communication tasks. We propose a modular relay positioning and trajectory planning algorithm that guarantees connectivity of the UAV mission team with minimum number of relays and feasible trajectories, where the cost, network structure and setup can be changed, allowing its use for different types of missions, without relying on infrastructure. We propose different approaches to relay position decisions and compare the proposed schemes with an ideal scheme and a Voronoi-based benchmark scheme. Our results show that different solutions are applicable for achieving fewer number of relay nodes, higher utilization or lower number of hops between the nodes. With the proposed scheme the maximum number of relays in the air can be reduced by up to 40% and utilization can be increased up to 50% in comparison to the benchmark scheme, with less average traveled distances and average velocities for the relay nodes. These advantages come with a cost of higher maximum number of hops compared to the benchmark.