A Novel UAV-assisted VANET Routing Protocol for Post-Disaster Emergency Communications

After natural disasters, such as earthquakes or tsunamis, terrestrial communication networks often become inoperative due to infrastructure collapse. Simultaneously, damage to roads and transportation systems inevitably isolates different parts of the affected area, making it challenging for emergency vehicles to reach critical locations and deploy mobile Base Stations (BSs). In such scenarios, Unmanned Aerial Vehicles (UAVs) serve as a flexible and efficient solution. With the capability to establish temporary communication links, UAVs can provide emergency coverage for ground entities. In this paper, we propose a Dynamic Priority-based UAV-assisted Vehicular Ad-hoc Network (VANET) Routing (DPUVR) protocol for post-disaster message transmission. Specifically, DPUVR is a trajectory-based method for controlling the direction of message forwarding. DPUVR utilizes a multi-attribute decision-making method to adaptively evaluate the message delivery capability of candidate nodes (in this paper, nodes refer to both UAVs and vehicles), taking into account trajectory similarity, surplus energy, link survival time, remaining distance cost and queuing delay. In addition, we propose a dynamic prioritization delivery model. It evaluates the priority of messages in node buffers, selects appropriate candidate nodes and then chooses the best relay for message forwarding to trigger timely and efficient message delivery. Extensive simulation results show that DPUVR significantly outperforms other baseline methods in terms of delivery ratio, overhead, average delivery latency and average buffering time.