Research On Application Of Complex Network Theory In WSN

As an information access technology，Wireless Sensor Network (WSN)is currently oneof the hot spots in the research field of information science. In WSN, data transmission isfrequent in the network, so, improving the efficient of data transmission and reducing thedegrees of separation of nodes, is very critical to acquire better performance of the network.Complex network, on the other hand, reveals many common features existed in natural andartificial networks, such as the characteristics of small world and scale-free. Rational use ofthese common characteristics is of great significance for improving the efficiency of datatransmission.This paper makes an intensive study of the application of complex network theory inWSN, in which the methods about the evolution of topology architecture and theimprovement of routing mechanism are designed. The main contributions of this dissertationare summarized as follows:1. Research on the connectivity of WSN. Under the assumption that the nodes aredeployed random, for a given node density, we discuss the requirements for no node isisolated and k-connected network. The results suggest that, for a given node density, theconnectivity is with relation to the radio transmission range.2. Characteristic analysis of topology characteristics of WSN. First, by rewiring a few ofrandom links of any node suggest that the small world phenomenon is still existed in WSN,where the links between nodes depend on the radio range. Second, by considering thedynamic of network and preferential attachment, the small world evolution model of WSN isproposed. In dynamic evolving process of WSN, there are three types of events as follows:adding new nodes, adding new links and links failure. The theoretical computing andsimulated results show that the degree distribution of this model follows a power law, and theaverage path length reduced sharply, show the network is small world.3. Research on the routing mechanism of WSN. This paper borrows from the concept ofsmall world and proposes a small world based routing mechanism for WSN. In thismechanism, apart from the information of neighborhood, each node also needs to maintain the information of a few distant nodes called short-cuts. By introducing the process ofneighborhood setting up and maintenance, and short-cuts selection and maintenance, therouting mechanism is explained explicitly. Our simulations try to analyse the effect of variousparameters such as neighborhood radius, the maximum short-cut distance, the number ofshort-cuts and the depth of search on the reachability and overhead. The results suggest thatthe short-cuts expand the view of network and reduce the degrees of separation between thesource node and the targeted objects, and due to routing very small data transfers, theoverhead is much smaller.