Research On Data Dissemination Mechanism Based On Density-Sensing For Vehicular Opportunistic Network

Vehicular opportunistic network (VON) is a new form of network, which does not require the completely end-to-end communication link, and mainly uses encounter opportunities to realize data communication between vehicles with "store-carry-forward"route model. VON is a special form of vehicular ad-hoc network with high time-varying of network topology, high cache demand and delay and other characteristics. In view of the above characteristics, the traditional data dissemination mechanism can't be effectively applied to VON, designing a suitable data dissemination mechanism for VON is of great significance. At present, the data dissemination mechanism is the key and hotspot in related fields, but traditional data dissemination mechanism look on only single environment, without considering the link break of inter vehicle communication by vehicle density changes when vehicles moving fast. Therefore, a data dissemination mechanism based on density-sensing for VON is proposed, including a data dissemination model based on density-sensing, a data dissemination mechanism based on density-sensing clustering and a cache update scheme.Firstly, according to three classical multicast routing protocols in VON, we study the performance of the routing algorithm and compared the experimental results for the further research. By analyzing data dissemination needs, a data dissemination model based on density-sensing for vehicular opportunistic network is proposed, which designs a clustering module based on density-sensing and data dissemination module. Among them, the clustering module based on density-sensing is in charge of the vehicles in the network node clustering and maintenance; the data dissemination module is responsible for data dissemination in cluster nodes and data dissemination between cluster nodes. Secondly, as the research focus for data dissemination mechanism, the clustering algorithm can improve the data dissemination efficiency, reduce network latency and so on. But traditional clustering algorithms do not consider the relationship between vehicle speed and node density, as well as the characteristics of data dissemination in different density.Therefore, a clustering algorithm based on density-sensing is proposed. The algorithm is aware of the network environment of node density, and considers node cluster structural stability and nodes selfish-degree for head selected in node dense environment, considering the meeting chance of vehicle nodes for selecting the cluster head in sparse environment. Then a data dissemination mechanism is proposed for vehicular opportunistic network based on those methods. By density-sensing clustering, the mechanism can achieve a good efficiency and low network latency for data dissemination in both dense environments and sparse environment. Finally, we design a comprehensive account of user needs and events real-time data dissemination cache update scheme, improving the data dissemination during event matching the hit rate.Simulation results show that the data dissemination mechanism based on density-sensing have higher data dissemination efficiency in highway of dense and sparse environment.