Robust airborne wireless backbone using low-cost UAVs and commodity WiFi technology

This paper proposes the use of low-cost unmanned aerial vehicles (UAVs) to enable communication between mutually unreachable ground stations in regions without communication infrastructure. The proposed method involves flying UAVs at communicable altitude in a pre-specified pattern over the ground stations. A fully autonomous control system based on the proportional integral derivative controller and the non-linear dynamic inversion controller has been built for this purpose. A modified Ad-hoc On-Demand Distance Vector (AODV) protocol is used to route data packets between the ground stations over the network formed by the UAVs using a delay tolerant approach. Using simulations, we show the effectiveness of the proposed solution, which consistently achieves a packet delivery ratio of above 90% regardless of number of UAVs. The average end-to-end delay drops steeply with an increase in number of UAVs. For a separation distance of 2 km between ground stations, four low-cost UAVs with commodity WiFi communications equipment can achieve an average end-to-end delay of 15 s and packet delivery ratio of 95%, thus giving a good balance between number of UAVs and average end-to-end delay.