Research And Application Of The Trust Mechanism In Vehicle Ad Hoc Networks

Opportunistic network is a new kind of wireless mobile self-organizing network, in which the message transmission relies on the communication opportunities by the nodes mobility. Opportunistic network can be used in a variety of fields, and the vehicle ad hoc network is one of them. The appearance of opportunistic network is contributed to increase the likelihood of message transmission between nodes in wireless network. However, it also brings great safety hidden troubles. For example, the network latency leads to the result that the message can not be timely to the destination node. The own energy constraints result in the appearance of selfish nodes and the rejection of forwarding message in the network. As a result, the transmission rate of message is descended. The presence of malicious nodes leads to the network is attacked. So the troubles would make the message can not be transferred safety in the network.To solve the security hidden danger in opportunistic network, vehicular ad hoc network and city vehicular ad hoc network, this paper proposes a series of trust mechanism to ensure the normal communication according to the different characteristics of the network. The research work is as follows.1) In the opportunistic network, this paper proposes a kind of nodes incentive mechanism based on price divided utility value. Through constructing the directed graph which weight of the ratio of price divided utility value, using the Dijkstra algorithm, and taking the network latency in the consideration, the mechanism finds out an optimal message transmission path which have a short delay time and the small ratio of price divided utility value. It resists the greedy behavior of selfish nodes in a certain extent, and effectively improves the performance of network.2) In the vehicular ad hoc network, this paper proposes a kind of trust model based on utility value in the network. Using the clustering model, the mechanism through constructing the vehicle level model and reputation model of nodes, the utility value of nodes can be concluded at the same time, the mechanism defines the events level model, it helps us to resist the greed of selfish nodes, ensures the secure transmission of message.3) In the city vehicular ad hoc network, this paper proposes a secure message transmission mechanism. The TPM chips take as the unique identification of vehicle nodes. Through calculate the friendly value between vehicle nodes and integrate the direction and speed of nodes, it is concluded that the utility value of nodes to measure the degree of trust between nodes. It can help to ensure the security of message transmission. In addition, the Floyd algorithm is used to calculate the shortest distance between intersections in city vehicle network, through that the mechanism can achieve the goal of transmit message quickly in the network.In summary, the security of message transmission is improved by using a series of research based on the trust mechanism in the network.