Research On Invulnerability Of Wireless Sensor Networks Based On The Properties Of Small World

Wireless sensor networks(WSNs)are usually deployed in a very harsh circumstances,the factors such as energy depletion,hardware malfunction and human invasion often lead to the node failure of WSNs,and further contribute to the reduction of the network connectivity and even the paralysis of the entire network.Therefore,the study of invulnerability has great significance to the applications of WSNs.Small world network is characterized by a high clustering coefficient and a small average path length.Introducing the properties of small world network into the research of WSNs is important to improve the network connectivity and invulnerability.In this paper,we study the invulnerability of WSNs based on small world characteristics,and propose two topology optimization strategies:(1)The sensor nodes of the wireless sensor networks are deployed densely,when sensor nodes are randomly distributed,the network may appear a large number of conflicts and congestion,which can increase the delay and reduce energy efficiency.Under this situation,we propose a novel method to construct WSNs with small world characteristics.Based on the analysis of clustering coefficient,we selectively remove some superfluous links to make the cluster more obvious.Then the search area is established for the node whose betweenness is the largest in its cluster.Finally,we need to find the qualified node in the search area and create shortcut among these nodes.Removing links can optimize the clustering coefficient and creating shortcuts can optimize the average path length.However,the optimization of one characteristic will weaken another characteristic.Therefore,in order to make the two characteristics optimal,the two parts can be implemented alternately.The simulation results show that this method can simplify the topology of network and optimize two characteristics of small world effectively.At the same time,under the circumstance of low redundancy,the network has good invulnerability.(2)Failure of some key nodes in the network can quickly lead to the paralysis of the network.Therefore,in order to improve the invulnerability of WSNs,we can relatively weaken the importance of the key nodes to avoid the failure of these key nodes.In view of this idea,we use betweenness to evaluate the importance of the nodes and present a method based on the characteristics of small world to improve the invulnerability of WSNs.The algorithm first selects a node randomly and divides the cluster by searching the qualified nodes based on the clustering coefficient of the node.Then,shortcuts are established between the nodes whose betweenness is the smallest in its cluster.The simulation results show that this method not only uniforms the betweenness centrality of the nodes,but also can greatly improve the network connectivity,effectively improve the efficiency and invulnerability of the network.