Intelligent UAV-assisted routing protocol for urban VANETs

The process of routing in Vehicular Ad hoc Networks (VANET) is a challenging task in city environments. Finding the shortest end-to-end connected path satisfying delay restriction and minimal overhead is confronted with many constraints and difficulties. Such difficulties are due to the high mobility of vehicles, the frequent path failures, and the various obstructions, which may affect the reliability of the data transmission and routing. Commercial Unmanned Aerial Vehicles (UAVs) or what are commonly referred to as drones can come in handy in dealing with these constraints. In this paper, we study how UAVs operating in ad hoc mode can cooperate with VANET on the ground so as to assist in the routing process and improve the reliability of the data delivery by bridging the communication gap whenever it is possible. In a previous work, we have proposed UVAR - a UAV-Assisted VANETs routing protocol, which improves data routing and connectivity of the vehicles on the ground through the use of UAVs. However, UVAR does not fully exploit UAVs in the sky for data forwarding because it uses UAVs only when the network is poorly dense. In this paper, we propose an extension of this protocol by supporting two different ways of routing data: (i) delivering data packets exclusively on the ground using UVAR-G; and (ii) transmitting data packets in the sky using a reactive routing based on UVAR-S. Simulation results demonstrate that the hybrid communication between vehicles and UAVs is ideally suited for VANETs compared to traditional vehicle-to-vehicle (V2V) communications.