A hybrid traffic geographic routing with cooperative traffic information collection scheme in VANET

The routing of data in inter-vehicle communication technologies has obtained tremendous amount of researchers' attention during the last few years. Many routing protocols utilize vehicular traffic information as a metric to determine optimal routing paths to transmit data in vehicular environment. Due to the difficulty as well as the enormous deployment costs of static nodes and the arduous effort to obtain non-real-time traffic information, the existing traffic information collection mechanisms could not provide the efficiency that is needed for the VANETs environment. In this paper, we present a novel collaborative real-time traffic information collection mechanism. It includes hybrid traffic information collection, road weight information dissemination, as well as the hybrid traffic geographic routing. The collaborative real-time traffic information collection mechanism effectively collects and disseminates real-time hybrid traffic information such as node density and network traffic load. In most VANET routing protocols, the network traffic load is always ignored and this action may cause network performance degradation in heavy-traffic load networks. In proposed hybrid traffic geographical routing, a forwarding node at a junction adaptively decides on a routing path based on the real-time hybrid traffic information. It consists of successions of road junctions to find the destination node for the data packet. Between two consecutive junctions on the path, geographical forwarding is used to select forwarding nodes on the road. Simulation results not only shows the proposed mechanism has the ability to collect real-time traffic information effectively with only slight control overhead, yet also has the ability to avoid from choosing an already congested path. Simulation results also show that the proposed mechanism outperforms routing protocols like GSR (Geographic Source Routing) and GyTAR (improved Greedy Traffic Aware Routing Protocol) in terms of average delivery ratio.