Repairing Coverage Holes In Coordinate-free Wireless Sensor Networks

Wireless sensor networks are self-organized network systems formed by deploying a large number of sensor nodes,and are usually used to collect physical environment information in the sensing area.With the interactive development of wireless communication,embedded system,and microcomputer computing,wireless sensor network has been applied more and more widely,such as military research,environmental monitoring,healthy life and so on.Wireless sensor network uses nodes to cover the sensing area for information collection.The data collected by wireless sensor network is only available when the rate of coverage of the network reaches the requirements.However,coverage holes appear easily in the network cause low rate of network coverage and may lead to untrusted network data.Therefore,the problem of coverage holes has become an important factor affecting the use and development of wireless sensor networks.This thesis focuses on the detection and repair of network coverage vulnerability to improve the rate of coverage.Since the installation of GPS devices on the nodes of wireless sensor networks may cause the network cost to be too expensive,this paper mainly proposes to use the location-relationship between nodes to judge the coverage hole and the hole repair scheme for the network without coordinate.The specific work is as follows:(1)This thesis identifies coverage holes by judging boundary nodes in the network.In a location-free network,we only use the local graph formed by each node and its one-hop neighbor to determine the location-relationship between the nodes.Compared with other studies on coverage hole detection,this method reduces the hardware cost and the communication cost,which saves the power of the nodes and the cost of the sensor network.Finally,the effectiveness of the proposed algorithm is verified by simulation experiments.Finally,simulation experiments verify that the accuracy of the algorithm is over 80% and the recall rate reaches 98%.(2)In the coverage hole repair work of wireless sensor network,we propose to build a network model by using the relative position relationship between nodes,and then calculate the relative positions of mobile nodes and boundary nodes to repair the hole after studying the position relationship between edges and vertices of geometric figures.The scheme uses a distributed method to calculate the node position,which reduces the storage cost of the node and nodes use communication to replace the invalid displacement of the mobile node to reduce energy consumption,thereby extending the life of the network.