关键词: 移动自组网, 网络安全, 声誉系统, 合作性

Abstract: In mobile ad hoc networks，nodes cooperate by forwarding packets for each other to allow them to communicate.The cooperation of nodes is very important.With lack of a prior trust relationship，the cooperative security schemes offer the effective solution to resolve the uncooperative behavior which launched by the malicious and selfish nodes in the mobile ad hoc networks.we present that an Optimized Local Reputation System.In our approach，reputation is exchanged in k-hop neighborhood，which not only can reduce the cost of system but also can fully learn the experiences from its neighbors.Binary Exponential Backoff Algorithm is adopted to deal with the uncooperative nodes.Our approach can effectively inspirit the nodes to cooperate，and enhance the performance of mobile ad hoc networks.

Key words: mobile Ad hoc networks, network security, reputation system, cooperation