研究传感器网络拓扑对节点失败的容忍能力,必须解决三个基本问题,容忍节点失败的定义是什么,如何评价拓扑的这种容忍能力,什么样的拓扑具有较高的容忍能力.当前有关无线网络容错拓扑的研究均将图的多连通性看成拓扑的容错性,以图形多连通度的大小来衡量拓扑容错性的高低.本文通过实例分析指出图的多连通性与容错性是不同的,并结合网络的可用性,给出拓扑对失败节点容忍的定义,在此基础上,根据随机故障和恶意入侵两类节点失败形成原因,给出了拓扑容错度和容侵度作为拓扑对节点失败容忍能力高低的评价标准,并利用这两个标准分析了传感器网络分层拓扑,得出其拓扑容错度随簇头节点比例提高递减、而容侵度随之递增的理论结果.
To develop new topology with more powerful ability to tolerate node-failure in wireless sensor network, the existing research regards fault-tolerance topology as the multiply connected graph, and use the connectivity of the graph as standard to evaluate the tolerance ability. In this paper, we argue that fault tolerance of topologies is not equivalence to connectivity of the multiply connected graph by illustrating some practical examples, and point out the following three questions should be answered. First, what is node-failure tolerance of topologies? Second ,how to evaluate this tolerance ability? Third,which type of topologies is more tolerant in node-failure? Then we define the concepts of node-failure tolerance and the degree of fault-tolerance and intrusion-tolerance. Then these concepts are used to evaluate the tolerance performance of hierarchy structure of wireless sensor network, and the conclusion is achieved that intrusion-tolerance degree is increasing with the ratio of cluster head increasing in hierarchy structure, but fault-tolerance degree decreasing.