UAV-to-Ground Multi-Hop Communication Using Backpressure and FlashLinQ-Based Algorithms

The use of Unmanned Aerial Vehicles (UAVs) for remote sensing and surveillance applications has become increasingly popular in the last decades. This paper investigates the communication between a UAV and a final control center (CC), using static relays located on the ground, to overcome the intermittent connectivity between the two end points, due to the UAV flight. Backpressure and FlashLinQ routing and scheduling algorithms are jointly applied to this scenario. Backpressure has been shown to be able stabilize any input traffic within the network capacity region without requiring knowledge of traffic arrival rates and channel state probabilities. FlashLinQ is used in the scheduling phase to derive a maximal feasible subset of links which can coexist on a given slot without causing harmful interference to each other. Moreover, to overcome the limit on long end-to-end delays of backpressure, we propose a modified algorithm, where relays are selected depending on their proximity to the CC and on the UAV trajectory. Through extensive simulations, we demonstrate that, compared to the benchmark solution based on backpressure, the proposed algorithm is able to reduce delay significantly without any loss in throughput gain.