Research On Publish/Subscribe Data Dissemination For Vehicular Ad-Hoc Network

Vehicular Ad-Hoc Network (VANET) is the hot research field of wireless Mobile Ad Hoc Network(MANET). VANET realizes the information communication and sharing between vehicle and vehicle, vehicle and infostation. Contrasting with former MANET, VANET has the problem of frequent varing network topology, unstable link among vehicles, short link duration time and unreliable wireless channel. So it is not effective to apply traditional data dissemination based on Internet and VANET in fast-moving vehicular network. Therefore design data dissemination algorithm in VANET is of great significance.In vehicular network, many factors such as road topology, traffic rules and human behaviors lead the network to diverse spatial distribution. The VANET has its unique mobile node spatial distribution features and network features, so researching on vehicular adhoc networks becomes the basic of the design of data dissemination. This paper selects three typical mobile models from existing mobile models, reveals and compares the mobile node spatial distribution features and network features of real vehicle moving traces and mobility models. The simulation results show that the node spatial distribution present obvious asymmetrical features and "hot spot" phenomenon. node spatial distribution and node mobility have much effect on the network features. the bring of car following and traffic light rules make the mobility models better imitate the real traffic situation. All above provide certain reference to the design of data distribution and the choose of simulation models and lay the foundation.In order to solve the problem of higher data transmission delay and the low rate of successful transmission, this paper takes advantage of rapid and stable characteristics of RSU backbone, combined with publish/subscribe system performance and propose an efficient data distribution algorithm. Firstly, we predict vehicle node positions in accordance with the history of vehicles access RSU. Secondly, according to the effective time of vehicle nodes subscribe messages and the number of nodes which subscribe the messages, we allocate the priority to the information stored in the RSU depending on the comprehensive weights. Finally, we impose restrictions on the packets according to the nodes density. The simulation shows that our proposed data dissemination algorithm improves the message transmission success rate, reduces the average transmission delay and the redundant copies of data packet. So the algorithm realizes the control copies of packets at the same time improve the performance of data distribution.