Researches On Structural Characteristics Analysis And Control Algorithms Of Fault-tolerant Topology In Wireless Sensor Networks

Under the restraint of the energy exhaustion and environmental damage, WirelessSensor Networks (WSNs) are usually was threatened with the energy exhaustion andenvironmental damage. Then due to nodes failure of the network topology, the servicequality of network connectivity and coverage are reduced. And the disconnection andcavitation of the network are easily appeared. Because the part (or all) of the networkmonitoring information cannot be passed to the destination node, the network can not benormally worked. Therefore, the research on the fault-tolerant topology is the mostfundamental basis of the practical application for the WSNs. And the research is importantin the WSNs security field. The node fault mode of energy exhaustion and environmentaldamage is built in this paper. The structure characteristics and control algorithms offault-tolerant topology is studied based on this model. The efficient control algorithms ofthe fault-tolerant topology are studied according to exploring the influence law oftopological node degree and degree distribution on the aspect of the integrated faulttolerance in WSNs. In this way, the efficitively tolerate of the topologies can be achievedduring the integrated node failures of the energy exhaustion and environmental damage.The main research works are as follows:Considering the nodes fault of the energy exhaustion and environmental damage, theintegrated fault model is built in this paper. And the influence law of the topological nodedegree characteristic on integrated fault tolerance is studied by using the inequalitymethod and the unary function extremum method. Using the law, the optimal node degreeis obtained. And the dual requirements of the network lifetime and the integrated faulttolerance ability are met. Then a redundant fault-tolerant topology control algorithm isproposed. The optimizing of the lifetime and integrated fault tolereance is realized byusing this algorithm.Considering that the redundant fault-tolerant topology cannot tolerate a large numberof nodes failure, a topology fault-tolerance measurement is proposed based on theeffectiveness of the network connectivity and coverage in this paper. The influence law of the topological degree distribution characteristic on the integrated fault tolerance is studiedby using the probability generating function and fault-tolerance measurement. Then thebest degree distribution of maintaining network connectivity and coverage service isobtained under the condition of integrated node failure during long-time work.In order to prolonging the network lifetime and reducing network interference, ascale-free fault-tolerant topology model is built based on the best degree distribution inthis paper. The scale-free fault-tolerant topology control algrotihm is proposed by solvingthe degree distribution expression of the lifetime and interference of scale-freefault-tolerant topology balancing. The effectively tolerate of integrated failure nodes isachieved by this algorithm. And the network lifetime is prolong, the network interferenceis reduced.Considering that the cascading failure usually appears in the scale-free fault-toleranttopology, a cascading failure model of the variable load and fixed capacity is built in thispaper. In the situation of large-scale cascading failure of scale-free fault-tolerant topologytriggering by a single failure node, the critical value of load is deduced according toanalyzing the influence law of the topology load on fault tolerance in case of cascadingfailure. The cascading failure causing by a single random failure node can be avoidedeffectively according to optimizing the parameter.