Location-Aided Delay Tolerant Routing Protocol in UAV Networks for Post-Disaster Operation

Wireless communication is essential for search and rescue operations in the aftermath of natural disasters. In post-disaster scenarios, unmanned aerial vehicles (UAVs) can be used to capture image and video data from the disaster area and transfer the data to a ground station, owing to their rapid mobility. However, packet forwarding is a challenge because of unstable links and intermittent connectivity in highly dynamic UAV networks. In this paper, we propose a location-aided delay tolerant routing (LADTR) protocol for UAV networks for use in post-disaster operations, which exploits location-aided forwarding combined with a store-carry-forward (SCF) technique. Ferrying UAVs are introduced to enable an efficient SCF, and this is the first attempt at introducing and using ferrying UAVs for routing in UAV networks, to the best of our knowledge. Ferrying UAVs improve the availability of connection paths between searching UAVs and the ground station, thus reducing end-to-end delays and increasing the packet delivery ratio. Future UAV locations are estimated based on the location and speed of UAVs equipped with a global positioning system. The forwarding UAV node predicts the position of the destination UAV node and then decides where to forward. The proposed LADTR ensures that the contact rate between UAV nodes remains high, which enables a high packet delivery ratio, and ensures single-copy data forwarding to avoid replication of each message. Our performance study shows that the proposed LADTR outperforms the four typical routing protocols reported in the literature in terms of packet delivery ratio, average delay, and routing overhead.