提出一种基于推荐证据的对等网络(Peer-to-Peer,P2P)信任模型RETM(Recommendation Evidence based Trust Model for P2P networks),解决了基于推荐的信任模型中普遍存在的在汇聚推荐信息时无法处理不确定性信息以及强行组合矛盾推荐信息引起的性能下降问题,同时,RETM采取推荐证据预处理措施,在合成之前有效过滤了无用的以及误导性的推荐信息,使得该模型具有一定的抗攻击性能.在推荐信息的查找问题上,RETM提出了基于反馈信息的概率查找算法,该算法在降低了网络带宽开销的情况下,提高了信息查询的准确率.实验证明RETM较已有的信任机制在系统成功交易率、模型的安全性等问题上有较大改进.
In Internet service fault management based on active probing,uncertainty and noises will affect service fault management. In order to reduce the impact,challenges of Internet service fault management are analyzed in this paper. Bipartite Bayesian network is chosen to model the dependency relationship between faults and probes,binary symmetric channel is chosen to model noises,and a service fault management approach using active probing is proposed for such an environment. This approach is composed of two phases:fault detection and fault diagnosis. In first phase,we propose a greedy approximation probe selection algorithm(GAPSA) ,which selects a minimal set of probes while remaining a high probability of fault detection. In second phase,we propose a fault diagnosis probe selection algorithm(FDPSA) ,which selects probes to obtain more system information based on the symptoms observed in previous phase. To deal with dynamic fault set caused by fault recovery mechanism,we propose a hypothesis inference algorithm based on fault persistent time statistic(FPTS) . Simulation results prove the validity and efficiency of our approach.
CHU LingWei ZOU ShiHong CHENG ShiDuan WANG WenDong
This article describes a new model of a cooperative file sharing system in a wireless Mesh network. The authors’ approach is to develop an efficient and cooperative file sharing mechanism based on opportunistic random linear Network Coding. Within this mechanism, every node transmits random linear combination of its packets according to cooperative priority, which is computed in a distributed manner according to the node-possible contribution to its neighbor nodes. With this mechanism, the more a node contributes to others, the more the node has chances to recover the entire file first. The performance metrics of interest here are: the delay until all the packets in a file have been delivered to all nodes, and an ideal packet size, by the use of which the authors can get the minimum transmission delay. Through extensive simulation the authors compare their mechanism with the current transmission process in a wireless Mesh network without random linear Network Coding. The authors found that using their mechanism, the nodes can cooperatively share the entire file with less transmission time and delay than the current transmission process without random linear network.
KIMBA DIT ADAMOU BoubacarZOU Shi-hongABDOU SaleyMA Yi-huiCHENG Shi-duan
