| A mobile Ad Hoc network is a self-organization,multi-hop and dynamic network without a central controller.The network is built spontaneously as devices connect without concrete infrastructures.Also,the flow of messages is quick and the base stations are damage-resisting.Relying on those merits,a mobile Ad Hoc network is for special purposes of military connection,emergency aiding,etc.However,due to some facts of the network like the mobility of modes,the vulnerability of transmission media,and the decentralized modes,a mobile Ad Hoc network is exposed to more attacks compared with traditional networks.Some “selfish” behaviors of internal networks impact the functions of network and sometimes lead to network paralysis.About this question,after analyzing some methods to detect selfish nodes,this paper presents a method of detecting selfish nodes based on a reputation evaluation mechanism.Firstly,according to some existing researches,this paper proposes a theoretical model DDRE which is data-driven one on reputation evaluation.Based on a weighted average method,the model can compute reputation values of nodes.With that new mechanism proposed in this paper,the reputational value of nearby nodes is shared and when the local history of reputational information cannot be retrieved.Besides,the reputational values will be updated automatically in view of changes of communicational information.Secondly,this paper finds a new mechanism which has four modules to evaluate reputation values of selfish nodes——a monitoring module to figure out communicational problems;an assessing module to keep track of reputation values which cannot be queried;a punishing module to deal with nodes based on punishing rules,and a responding module to make performances after receiving messages from assessing and punishing modules.Finally,with the help of a NS2 simulation system,the paper also makes experiments and analyzes results from the mobile Ad Hoc network with a reputation-appraising mechanism or not.Again,the outcomes prove that nodes in a reputation mechanism are less to be selfish.Relying on the reputation system,the data delivery is more effective;the throughput capacity of network is higher;the expenses of route are less,and the overall functions of the network are enhanced. |
