Research On Wireless Sensor Network Topology Control Algorithm

Wireless sensor network (WSN) which is able to perceive and collect the information of objects under monitoring in the distribution of WSN, process and send them to the client, plays a key role in the next generation of networks. Since WSN is energy constrained, topology control algorithms which are designed to save energy have become the research hotspot in recent years. Topology control algorithms archieve their goals by making special modifications to the network topology. Another feature of WSN is that there is not any network infrastructure, such as base stations, in it. All the sensor nodes have been built equally in hardware and software, which makes them self-organized to form the network topology. Obviously, distributive algorithms are applicable to WSN. So, this article focuses on localized distributive algorithms of topology control. An algorithm which only needs information within a constant number of hops is called "localized".Topology control algorithms modificate the network topology in mainly two ways:One way is to adjust the transmit power of sensor nodes, in order to save energy; the other one is to construct a backbone of network, which divide the nodes into different levels so that the energy consumption will be balanced among them. Finally, the lifetime of the network will be prolonged. We noticed that the first kind of algorithms make a flat topology as well as the latter kind makes a hierarchical network.According to the research on the relationships between topology structure and energy cost of topology algorithms, we find that the hierarchical structures lead to a better performance on energy cost of algorithms. Further more, we conclude that the tree-type backbone has a large energy cost because there is no localized maintenance scheme. Under these two conlusions, we proposed an algorithm, "Meshed CDS", which makes a mesh connected dominating sets (CDS) to be the backbone. It has a low energy cost since in most cases, the backbone can be maintained using localized manner.Reducing the number of backbone is essential for WSN because the backbone nodes on backbone consume more energy than the other nodes. We proposed a "MESH-CDS" algorithms which is not only has a completely localized topology maintenance scheme, but also much less number of backbone nodes. In addition, it can be run asynchronously among all the nodes in the network.At last, we proposed an algorithm which is named "DMESH-CDS". This proposal selects the nodes with lager degrees to be backbone nodes. The simulation result shows that the backbone's size has been decreased compared with "MESH-CDS".