Position Based Adaptive Routing for Vanets

Routing plays a very significant role in multi hop data dissemination in Vehicular Ad-Hoc Networks (VANETs). Wehave proposed a Position based Adaptive Routing (PAR) protocol which is scalable for different network densities in VANETs. This scheme uses Preferred Group Broadcasting (PGB) for route discovery. In this mode, after broadcasting the request for route discovery the source node starts listening to the channel. If the packet is not further rebroadcasted by any neighbor in a set timeout, then it repeats the broadcast. This process is repeated until the request reaches the destination. The destination keeps on accumulating route requests coming from different paths until predefined time. It then chooses the least cost path as route reply. It uses the set of traversed anchors for sending the unicast route reply to the source node. PAR uses Advance Greedy Forwarding (AGF) for data forwarding and greedily forwards the data packet to the next anchor towards destination node. It switches to carry and forward mode once it finds partitions in the network. The intermediate vehicle buffers the packet until next junction and switches back to position based scheme and greedily forwards to next node in range which is closest to the destination. To have an end to end connectedpath, it uses guards to guard anchors tied to different junction and geographical locations in the network. The algorithm is scalable and exploits advantages of existing techniques already developed for specific scenarios in VANET. Results show that the service ratio and packet delay of PAR are higher than its counterparts.