The Research Of IVC System Technologies Basing On The Wireless Sensor Network

With the development of modern traffic and logistics,the demand of the fluency of traffic and the efficency of logistics transportation is vital for intelligent transportation system(ITS).At present,the trend of ITS is to integrate the advanced information technology,communication technology,electronic sensor technology and computer process technology,and to improve the traditional ITS in order to enhance the efficency of resource using and system safety and to reduce the resource comsumption and environment pollution.Among ITS,the inter-vehicle communication system(IVC) concerns about the information exchange between the moving vehicles,which makes use of wireless sensor network(WSN) communication and node localization technology to realize the intelligence of vehicles,then the vehicles can acquire the information from neighbor ones and control its moving status,not only can this control the traffic jams and increase the useage rates of roads in result that decrease the pollution caused by them,but also can prevent or reduce the traffic accidents to ensure the safety of driver and pedestrian.As one of important applications of intelligent vehicle technology,the inter-vehicle communication based on the wireless sensor networks is one of the ITS research fields.This thesis analyses the development of domestic and foreign ITS technology that is combined with current wirless sensor networks research,propose the research about the IVC networks key technologies to realize the communication between vehicles.Firstly,in chapter 1,the situation of domestic and foreign ITS development is introduced,and the development of wireless sensor autonomous networks is illuminated.Then the current situation and the future trend of IVC research are proposed,the major research work in this thesis is presented.In chapter 2,basing on the analysis of the mode of inter-vehicle communication, and the features of the system structure of wireless sensor autonomous networks,the main key technologies about IVC system with wireless sensor autonomous networks are expatiated on.In chapter 3,after studying on the medium access control(MAC) protocols in wireless sensor networks,some exist problems about MAC layer technology are taken into account.The performance of the present MAC protocolos which are suitable for IVC networks is analysed and summarized.After modeling IEEE802.11 DCF protocol and studying on the work principle,an unbalance of vehicle nodes' access wireless channel is found when the network packeload is heavy.So A new adaptive adjustment backoff algorithm basing on the evaluation of nodes' access time is proposed.This algorithm is verified and analysed through NS2 simulation, the result shows that the algorithm can keep the fairness of nodes' access channel with less effect on the throughput of networks.In chapter 4,the clustering communication mode is proposed to apply in IVC networks in the result of the character of dynamic changes of topology caused by vehicles' wide distribution and movement.After analysing and studying on The WSN clustering principle and the design standard,and on the basis of the existed clustering algorithms,a new mobility adaptive clustering algorithm basing on vehicular multiple parameters weighing is presented.The stability of this clustering algorithm is verified and formulated through mathematical model and theory.Then in NS2,a new class library is designed for this algorithm,with which the algorihm is realized and simulated by programs.The simulation results indicate the stability and packet transmission etc.of this algorithm in the vehicular traffic scenario.In chapter 5,after anlysing and studing on the design method and category of routing protocols for wireless sensor autonomous networks and the characters and requirements of IVC routing protocols,The position-based and non-position-based routing protocols are studied for the IVC sytem,and the features of these tow typical routing protocols are illustrated.A new routing protocol based on clustering algorithm with vehicular multiple parameters weighinig is proposed for IVC networks,meanwhile a modified packet forward algorithm called vehicular packet greedy forwarding(VPGF) is introduced and a timeout waiting cycle algorithm in route maintenance is introduced to process the two kind of node's disconnection respectively.The work principle and data structure are interpreted and the protocol is programmed in NS2 to simulate,the performace of routing protocol such as end-to-end delay and route discovering time etc.is analyse by the simulation result.The chapter 6 summarizes the main work and achievement of the thesis,and makes the forcast to the research work and development direction in the future.