Research On Access Selection Mechanism In Vehicular Heterogeneous Networks

With the rapid increasing popularity of wireless vehicular networks and the number of vehicles equipped with wireless communication interface, data transition between vehicles on the road has been drawn more and more attention. Vehicular Heterogeneous Network(VHN), a special type of wireless vehicular networks, has the characteristics of both vehicle networks and wireless heterogeneous networks. Therefore, it’s crucial for a node in the VHN to choose an access network.Currently, most of the access network mechanisms for a node in VHN concerned about only one node. This node should detect and assess the current networks and select one which meets its needs best, then switch to the selected access network to download data all by itself. While in practice, vehicles on the same road may need the same application or same data, such as the map of current road or the real-time traffic information and so on. And when they decide to corporately download these applications, they can reduce the total access costs.In this paper, two kinds of access selection mechanisms are proposed for nodes downloading data cooperatively in VHN. These two mechanisms are individual-pay access selection mechanism and share-cost access selection mechanism. Individual-pay access selection mechanism mainly focuses on scenario where only the source node needs to download data. This mechanism is composed of one pricing strategy based on sharply formula of cooperation game theory and one access node selection strategy for access node confirmation. For share-cost access selection mechanism, it is proposed for the scenario where nodes around the source node demand the same application as the source node. The price of share-cost access selection mechanism is calculated according to the proportion of profits which brought by cooperation. And its access node selection strategy is similar to the individual-pay access selection mechanism. After comparing the price of source node and candidate access nodes, the source node takes two parameters, price and the ratio of price and quality, into consideration. Combining these two aspects, the source node selects the access node which satisfies it most to cooperatively complete the data download and gain a high quality of service with lower price.In this research, MATLAB simulation tool is used. First, this paper compares the influences caused by different values of price and ratio of quality and price parameters of individual-pay selection mechanism and share-cost access selection mechanism separately. Then, we compare the performance of the proposed two mechanisms with current vertical handoff mechanism. At last, for the scenario that nodes around the source node may demand the same data or may not, that is where individual-pay access selection mechanism and share-cost access selection mechanism are used at the same time, we compare the price and ratio of quality and price influenced by the different ratios of interested nodes. The final results of the research prove that our proposed individual-pay access selection mechanism and share-cost access selection mechanism can ensure the quality of service while reducing access costs. Meanwhile, in order to reduce price and improve service quality as much as possible, source node prefers to choose the node which uses share-cost access selection mechanism to download data cooperatively.