Real-time Data Dissemination Of Guidance Information In Its

In recent years, with the development of economy and expanding city construction, the number of cars has soared, which caused a lot of traffic problems, especially in the urban traffic environment, and made the intelligent transportation vehicle communication system become one of intense researches. VANET(Vehicular Ad Hoc Network) technology is the key factor of this research. To avoid traffic jams and traffic accidents, effective management and guidance become the key of intelligent transportation, which make the study of real-time data dissemination of guidance information most significant. However VANET has the characters of autonomy, no fixed structure, multi-hop routing, dynamically changing in network topology, limited in the network capacity and high scalability, which makes the algorithms cannot get ideal effect in VANET, which do well in MANET.Aiming at these problems, with the regularity and single-dimension of vehicle movement and characteristics of urban traffic network, the thesis designed a real-time data dissemination mechanism of guidance information based on VAWCA(VANET Adaptive Weighted clustering Algorithm). The mechanism considers factors of the vehicle speed, connectivity, node location, average communication time of the nodes in VANET, calculates the comprehensive weight to form stable clustering network structure for the vehicle network urban traffic scenes, and disseminates different types of information in this network.Due to the variation of the network node density and ways to disseminate information, the thesis adopts four strategies to improve the network performance: load-balancing strategy, stability guaranteeing strategy, emergency information broadcasting and unicasting scheme. The load-balancing strategy is mainly for dense traffic network scenario, considering network resource utilization, transmission efficiency and load ability, to make the whole network achieve load-balancing as far as possible; stability guaranteeing strategy is mainly for sparse traffic network scene, reduce jitter of cluster structure caused by weak node connectivity, to improve the algorithm performance; Emergency information broadcasting scheme considered the particularity of the emergency information transmission, taking advantage of the stronger transmission ability of RSU, to improve the real-time performance; Unicast scheme is to request and receive information based on the network constructed by clustering algorithm and take advantage of the characteristics of road and traffic, to make the usage of network resources efficiently.Finally, the thesis sets up the urban traffic simulation scenario based on NS3 simulation platform, and designs the performance indicators and the simulation parameters. Through the comparison and analysis of the simulation results of VAWCA and VWCP(Vehicular Weighted Clustering Protocol), it is proved that the VAWCA has better load-balancing, real-time and stability in unicasting scenario, the emergency information broadcasting scenario and general broadcasting scenario.