A Novel Approach to Reliable Message Broadcasting in Vehicular Ad hoc Networks by Prioritizing both Messages and Density Based Regions

Vehicular Ad hoc Networks (VANETs) are an outgrowth of traditional Mobile Ad hoc Networks (MANETs). VANET is mainly used to model communication in a Vehicular environment where the vehicles are considered as VANET nodes with wireless links. It enables the communications among vehicles and between vehicles and Road Side Units (RSU). In Peer-to-Peer communication, a vehicle can send message to any other vehicle in the network. In doing so, if the destination vehicle is farthest from the source vehicle, then propagation delay is more for the delivery of messages. For a better delivery ratio and to reduce broadcast storms, a message has to be relayed through intermediate nodes known as representative nodes (RN)s to the destination. The main requirement of VANET is location information. Using Greedy Forward algorithm, messages to farthest nodes are transmitted by computing RNs. Though we communicate with the farthest node through representative nodes, due to the special characteristics of VANETs such as high mobility, unstable links or dynamic nature of vehicles, representative nodes positions are to be computed dynamically. If the information about the high density region and low density region are gathered then the problems that arise with sparse VANETs also can be minimized. Otherwise the prior approach sends information to low density region continuously than high density regions. This problem can be minimized if we apply DBSCAN algorithm to form clusters (regions) using location information, then high density regions can be given highest priority for message transmission. As VANETs main characteristic is urgent message transmission, the messages are to be prioritized and then transmitted over the network. In this paper, Greedy forward approach and DBSCAN algorithms are pipelined to increase the performance of broadcasting messages over the VANET. In addition to this, in this paper, we also prioritize the messages for urgent message transmission over the VANET. This provides hybrid solution to the lossless instant messaging mechanism as this works on real time environment. Keywords: VANET, Representative Node (RN), Road Side Unit (RSU), Global Positioning System (GPS),Greedy Perimeter Stateless Routing (GPSR) , DBSCAN (Density Based Spatial Clustering of Applications with Noise)