Research On Energy Saving And Fault Tolerant Topology Based On The Theory Of Scale-free In Wireless Sensor Networks

Because of the power law property of degree distribution,the scale-free network makes the network topology have stronger fault tolerance and stability than others in the case of random node failure and make it more suitable in the area of the inaccessible and harsh environment.The performance of the topological structure are the basic guarantee that affect the survival time of network.Therefore,topological structure of WSNs is studied in this thesis based on power law property of the scale-free network,which has the advantages of enhancing network stability,fault tolerance and equalizing network energy consumption.At present,most scale-free network models are derived from the BA model.But the nonnegligible difference with real network is demonstrated when the model is applied to our life,which shows much more limitations.Therefore,the existing models are improved and extended in the thesis to meet the topological structure characteristics of more real networks.Firstly,considering that the BA model only focuses on the effect of the node lifetime to the network topological structure,together with the fact that low energy utilization will shorten the lifetime of network,the energy efficient scale-free topology model is proposed based on analyzing the influence of average network residual energy and communication radius on the network lifetime.During the topology evolution,the residual energy of node,the communication radius and the node degree are considered synthetically by proposed model and the corresponding adjustment parameters are adopted to make those nodes with more residual energy have high connection probability.Both the theoretical analysis and the simulation results show that the proposed model not only has the power law property of scale-free network with good stability,but also can balance the energy consumption of the nodes and the network,thus can prolong the network lifetime.Secondly,due to the difficulties that the dissipation of energy and the poor effect of intrusion tolerance of topology in the practical application of WSNs,the distance between cluster head nodes and the residual energy of nodes are considered to make the cluster head nodes with high residual energy have higher connection probability when constructs the network topology between clusters.By the methods of random walk strategy combined with the improved scale-free network ‘growth' and ‘preferential attachment',the random-walk scale-free topology model is proposed commensurately.The simulation results show that,the proposed topology not only has the power-law characteristic of scale-free network,but also possess a good stability and fault tolerance respectively.Finally,two improved algorithms are verified on the hardware platform of topology network,which is built by the sensor node CC2530 module,to get the fact of the improved algorithm in the thesis.