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As a kind of centreless, self-organized networks, Ad Hoc networks is widely used since they don’t need the support of basic establishment in information networks, and they are suitable for battlefield, disaster, temporary session and so on. Because of wireless communication, distributed control, etc, there are many security risks in Ad Hoc networks. With the expansion of the network size, hierarchical structure is commonly used to increase network’s scalability, and the security of the Hierarchical Ad Hoc networks becomes a hotspot.A dynamic reputation evaluation model is proposed to meet the characteristic and security requirement in hierarchical Ad Hoc networks. This model consists of reputation calculating, reputation management and reoutation updating. In reputation calculating, considering different roles of cluster head, gateway and cluster member in hierarchical Ad Hoc networks, different calculating methods are taken respectively, the reputation evaluation is more accurate and reasonable through the nodes cooperation in node behaviour and routing; In reputation management, the reputation evaluation is managed by cluster head to solve the slow convergence issue in the calculation caused by complex computations, which is suitable to the need of network extension; In reputation updating, reputation information of nodes with different roles updates with the reputation information of correlation nodes, encouraging the collaborative of cluster head and cluster member, improving the probability of cluster member to participate in network.Using of simulation software, such as NS-2, Dynamic Reputation Evaluation Model based on Node Roles is tested. The results show that, the model can more real-time and accurately reflect the security status of nodes, routing is choosed and adjusted based on the security status in time, which protect the routing’s relative safety and reliability, improve the network performance, is suitable to the security requirement of hierarchical Ad Hoc networks.
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