Research On The Coverage And Energy-Efficient Problems In Wireless Sensor Network

In Wireless Sensor Networks, coverage and energy-efficient problems are the key issues. The coverage degree is in contrast with energy consumption. In order to guarantee the coverage degree in the region of the WSN, it is necessary to deploy more sensor nodes in this region. Thus, it follows that there are many redundant nodes. Much energy could be wasted by these redundant nodes. It goes against energy-efficiency. To solve this problem, this thesis studies energy-efficient coverage problems. We have accomplished the following works.First of all, after introducing the existing coverage algorithms, we analyze their advantages and disadvantages. Based on this, we propose a quantitative criteria of energy utilized ratio, which can measure the use ratio of the energy. Then, we analyze the relation between energy consuming and the size of sensing range and communication range, combining energy consumption model. Then we come to the conclusion that there is little relation between the energy consumption and the number of active sensor nodes; it can save energy and enhance energy utilized ratio to reduce sensing and communication ranges. Based on these points, this thesis brings forward a method to reduce the energy consumption and prolong the lifetime of WSN through adjusting the sensing range of a sensor node.Secondly, we propose a generalized method of scheduling the node between"active and sleep", that is, adjusting the sensing range to appropriate size. It can enhance energy utilized ratio, and invoke self-healing work to eliminate the coverage hole in WSN and prolong the lifetime. The results of the simulation show that the new method enhance energy utilized ratio, and prolong lifetime of WSN with dump energy achieve balanced status. In the same time, this method will avoid invalid of existing algorithm because of the error coordinates. System scalability performed well.Thirdly, aiming at shortage of ASR-DLM, an improved algorithm is presented and completed. It convert the area coverage to coverage of discrete targets, reducing the difficulty of coverage, enhancing the energy utilized ratio and saving energy, prolonging lifetime. Though this method cannot guarantee completely coverage, it can achieve high coverage degree, practicality is very good. It make sense in coordinate-free situation.