A Study On Performance Analysis Of Wireless Inter-vehicle Communication Systems In Traffic Streams

Wireless inter-vehicle communication(IVC) systems based on mobile Ad Hoc networks have drawn increasingly research interests in recent years. As a new research direction in intelligent transportation systems(ITS),IVC has been a hot research topic in many countries, for IVC systems can improve traffic problems and enhance road safety. Most researchers currently concentrate on protocols and algorithms of different layers of vehicular Ad Hoc networks(VANet) to analyze the communication performances of VANet. However, in real traffic networks, whether a vehicle is equipped or not is random, and the state of high speed, acceleration and deceleration etc can cause dynamic communication topologies on the road. Therefore, it is hard to maintain a stable multihop communication path between two equipped vehicles of long distance. In this sense, it is need to study the communication performances of VANet under the influence of dynamic traffic flows. In this dissertation, it is supposed that whether a vehicle is equipped or not is random, and the probability is assumed to be the market penetration rate. By combining traffic flow theories with NS-2, this dissertation studies the communication performances of VANet under the influence of dynamic traffic flows. Together with further investigations, the study could be helpful for determining and designing appropriate software and hardware of IVC systems. The main works in the dissertation are presented as follows:1) In chapter 2, the basic traffic flow theories are introduced, which are the fundamental theories of communication scenarios of a uniform traffic flow and a traffic flow with a shock wave. The meaning of studying a communication scenario with a special shock wave is also stated.2) In chapter 3, the success rate of information transmission for different traffic densities, communication ranges and market penetration rates are analyzed based on traffic flow theories and the model of connectivity.3) In chapter 4, the architecture of protocols of VANet are analyzed from different layers.4) In chapter 5, two simple communication scenarios are first constructed, and throughput and end to end delay of information transmission with NS-2 are analyzed. In scenarios of dynamic traffic flows, a new Monte Carlo simulation model which is different from the model of connectivity is first proposed. Then two communication scenarios-a uniform traffic flow and a traffic flow with a shock wave are built using of NS-2 to carry out Monte Carlo simulation trials,and then the throughput and end to end delay of information transmission for different traffic densities, communication ranges and market penetration rates are studied. The comparison of the results with the model of connectivity gains a good effect. The simulation results show that the two models can complement each other for the better analysis of the communication performances of VANet.At last, the work of the study is summarized, and the direction of future work is pointed out.