Spotlight Flooding: Enabling Point-to-Point Control Connection in Urban UAV Networks

The use of Unmanned Aerial Vehicles (UAVs) has been proposed for numerous applications from recreational photography to commercial deliveries and infrastructure monitoring. But their effective deployment depends on the establishment of an Unmanned Aerial Traffic Management (UTM) which in turn requires reliable communication protocols to ensure safe and efficient operations. Recently, Rate Decay Flooding (RDF) was proposed as a novel protocol to enable position sharing among UAVs, realizing one of the major UTM applications. Another application is the provisioning of a redundant control connection which allows for point-to-point communication between a UAV and its operator in case their proprietary primary connection breaks. Every protocol used for this must harmonize well with RDF so that both applications can be realized at the same time. In this work we propose Spotlight Flooding (SLF) and its enhanced version SLF+, which build on top of RDF to realize a fast and reliable point-to-point connection between any two nodes in the network. These protocols are evaluated in an open-source simulator considering two scenarios. First, we consider a single UAV in distress using SLF/SLF + to explore the performance of our novel protocols for networks of up to 525 UAVs. The results show, that even for large networks, SLF+ achieves a Packet Delivery Ratio (PDR) above 90 % at an end-to-end delay of less than 60 ms. Additionally, we evaluate a scenario of 300 UAVs with an increasing share of UAVs using SLF/SLF+. Again, even if half of the UAVs in the scenario use SLF/SLF+ a PDR above 90 % is achieved at a delay of 142 ms.