Research On Coverage Maintenance In Wireless Sensor Networks

With the rapid development of Sensor technology, Micro-Electro-Mechanic System(MEMS) and wireless communication technology, Wireless Sensor Networks(WSN)has become increasingly nature. WSN has been more and more applied in military security,health care, space exploration, disaster rescue, environmental protection and other fields,undertake the complex and dangerous task,particularly in the area the human can't visit. The coverage of network is considered as an important measurement of the WSN's quality of service. However, the coverage holes may exist in the target area, due to random deployment of sensor nodes, node energy depletion, or the damage of the sensor. The appear of the coverage holes not only cause the information cann't be perceived in part area of the network,but also interrupt some of the data transmission channels, affect the data transmission, and thus debase the performance of the entire network, shorten the life of the network. This situation restricts the large-scale application of WSN, so formulate relevant coverage hole healing plan and maintenance the network coverage, is a problem should be solved.Based on the advantages and disadvantages of WSN coverage hole healing algorithm,this paper introduces two coverage hole healing algorithms,one is the Mobility of Two layers hole's Boundary node based Hole Recovery algorithm,and the other one is Patching Algorithm based on Mobile nodes. Then the MATLAB is used to simulate the experiments to verify the effectiveness of the two algorithms in this paper.Firstly, we introduce the basic concept and characteristics of the coverage hole in the WSN, analyzes the existing coverage hole healing algorithms, and focus on compare several typical kinds of coverage hole healing algorithms. At the same time, we point out the considered issue in coverage maintenance research. Secondly we study the coverage hole healing algorithms based on mobility of two layers hole's boundary node. Existing coverage hole healing algorithms based on limited mobility, only use the mobility of boundary node to heal the smaller coverage hole, and the mobility of other node is wasted, leading to low efficiency of the network maintenance. For this shortage, this paper proposes a algorithm named the Mobility of Two layers hole's Boundary node based Hole Recovery algorithm,which use the mobility of the second layer boundary node, that the non-boundary neighbors of the boundary node, to heal the coverage hole. In this method, the boundary node judge the healing ability can meet the requirements of the hole on their direction of movement before it move, if can't meet, send information to the non-boundary neighbors, let the neighbors move to its moving direction,to increase its moving distance,so as to improve the healing capacity of the node. The method greatly improves the maintenance ability of network. Finally we study the Patching Algorithm based on Mobile nodes. The method is based on edge information of the coverage hole, instruction redundancy dormancy mobile node moves to the best location, for healing the coverage hole. Existing methods simply consider the edge information of coverage hole, make the mobile node and the original network produces too much redundant. In this paper, a algorithm is developed to optimize the edge information of coverage hole, make the number of mobile node optimal, maintain the network coverage and prolong the network lifetime.