Communications Link Delay Analysis for a Swarm of UAVs Using Fading Channel Models

Swarm of unmanned aerial vehicles (UAVs) have been increasingly used in applications such as photogrammetry, payload delivery, precision agriculture, among others. A swarm can accomplish tasks more efficiently by covering larger areas in less time. Research show that the communication link delay among UAVs in formation stability strategies for multi-agent path planning such as control law or machine learning algorithms, is crucial. This study presents an analysis of delays between two flying UAVs. We modelled a 2.4 GHz communication link between two UAVs using Rayleigh and Rician fading channel models, calculating link delays over the flight time. Theoretical results were validated through flight tests with 2.4 GHz transceivers attached to two quadrotors following a coordinated flight plan and the link delays were measured using the timestamps of transmitted test packets. These results enable the characterization of 2.4 GHz communication link delays in a swarm providing insights for formation stability strategies.