Research On Coverage-hole Patching Algorithm In Wireless Sensor Network

Wireless Sensor Network is one of the three pillars of constituting the Internet Technology, and is pre-dicted as a key technology for the future world. It has wide application future, and mainly has been used inthe field of environment, military, medical, traffic management and other applications. In the wireless sen-sor networks, coverage quality is one of the important indicators to measure the performance of the net-work. Since some of the sensor nodes that in the process of transferring data appear the energies depletingtoo fast due to forwarding data is excessive, or suffered from attack, failure by unknown reasons is failure,and that inevitably lead to the coverage area appearing “hole”. The existence of coverage holes will accele-rate the death of sensor nodes that is near, and reduce the coverage quality and connectivity of network.Therefore, using effectively method to patch coverage holes or redeploy the network could improve the ef-ficient use of network remaining resources and extend the network lifetime.To solve this problem, firstly, this paper respectively states the algorithms of coverage holes in thewireless sensor network at home and abroad, and gives the correlation analysis. Under the different net-work model, this paper proposes two kinds of patching algorithm for coverage holes that can patch cover-age holes without changing on the basis of known network coverage structure. In this paper, the main re-search includes three aspects as followed:1. The research of coverage holes patching in wireless sensor network are respectively stated. For thecoverage holes problem, there are general two solutions strategies:(1) awakening nodes that are sleep ofwireless sensor network;(2) deploying new static nodes or mobile nodes in coverage holes. This paperanalyzes and discusses that coverage holes patching algorithms related to this two solutions strategies, andprovides the application environment as well as the advantages and disadvantages of this two solutions.2. Distance-assistant coverage hole parching algorithm is proposed. This algorithm is applied to thestatic sensor network which sensor nods is intensive distribution, or meets multi-coverage. Thehole-boundary node which is in the edge of the coverage hole awakens the redundant node that the distanceinformation is optimal to replace the failure node within its communication range. It can patch coverageholes without changing on the basis of known network coverage structure. Since nodes are randomly dep-loyed in the monitored region, it is often still remaining a lot of redundant nodes that have not been fully utilized when the network is failure. This algorithm is mainly using the resources of the remaining nodes inthe network to achieve the purpose of patching coverage holes. Simulation results show that for the samesize and shape coverage hole, compared with other algorithms, this algorithm can meet the network cover-age rate and awaken the less number of redundant nodes, and ensure the good redundant nodes average uti-lization at the same time.3. Based on the mobile nodes, a coverage hole patching algorithm is proposed. This algorithm is suit-able for hybrid wireless sensor networks. Using mobile sensor nodes are able to better solve the coverageholes problem. After detecting coverage holes that exist in the monitored region of the network, it calcu-lates the virtual mobile point that places the mobile sensor node. On the basis of the filling process of thisalgorithm and the minimum total moving distance method, that can guide the mobile sensor nodes to thevirtual mobile point for increasing the coverage area and reducing the coverage holes area. Simulation re-sults show，under the same network structure to compare with other algorithms, this algorithm can meet thenetwork coverage rate, and has obvious advantages in the number of mobile node that is used to fill cover-age holes, hole patching rate of single mobile node and the total moving distance. In this paper, the totalmoving distance of mobile nodes measures the total energy consumption in the network. This algorithm caneffectively reduce the total energy for moving, and extend the network lifetime.