A Fuzzy Reputation System in Vehicular Ad hoc Networks

Vehicular Ad hoc Networks (VANET) rely on the cooperation of the nodes to forward packets for each other. Some nodes may decide not to cooperate to save their resource while still using network resources. These nodes are called selfish. It has been shown that presence of such selfish nodes degrades the overall performance of a vehicular ad hoc network. To address this problem, we propose a fuzzy reputation system to discipline selfish behavior and encourage packet forwarding. Different from traditional reputation based solutions, our scheme doesn't rely on judgments about a node by its neighbors. So the misjudgments about a node which is a serious vulnerability in existing solutions have been eliminated. Our solution consists of two major components: The Forward Manager and the Fuzzy Reputation Manager. The Forward Manager in each node keeps track of the number of received forwarding requests and the number of packets which have been forwarded so far. The Fuzzy Reputation Manager checks each packet's source node to see whether it is selfish or not. Packets belong to selfish source nodes eliminate from the network. The simulation results have shown that the proposed scheme can successfully increase network performance.