JUNCTION ADAPTIVE REACTIVE ROUTING (JARR) PROTOCOL FOR VEHICULAR AD-HOC NETWORKS IN A CITY ENVIRONMENT 1-3.

摘要

The routing protocol was designed for VANET in a city environment. The main objective is finding not only the shortest but the most efficient path for a packet to reach its destination. Packets are routed through the fastest paths as opposed to the shortest. Fastest path is defined as the quickest time for a packet to reach a destination irrespective of distance. While the shortest path is still considered, the routing protocol adapts to the network conditions and performs routing reactively. Making use of the city topology, packets are routed from junctions to junctions. This means that routing decisions are made when a packet arrives at a junction, to decide which path to take next in order to reach the next junction. This process continues until the packet reaches its destination. The paths as well as next hops are chosen based on a calculated weighted score. The paths or next hops with the highest score will be chosen. The algorithms that calculate the scores takes into account the vehicle's velocity, direction of travel, current position and vehicle density information. Depending on location of the vehicles and network conditions, these factors will have different weight on the algorithms. With varying algorithm in different conditions, a packet has to switch between different forwarding modes. The different modes relate to the current location of a vehicle and affect the algorithm accordingly. Adaptive beaconing component is used to cope with situations such as network congestion when there are a lot of vehicles beaconing at the same time. The beaconing rate will be adjusted according to estimated network conditions. The information gathered would be used to estimate the density of a path.