The Research Of Wireless Sensor Network Coverage Problem Based On Node-scheduling Strategy

Wireless sensor network is composed of a low power consumption, coverage monitoring and self organizing network having communication ability, can be widely used in many fields such as military, medical, living and so on. But because the sensor nodes in wireless sensor network has the limited computing capacity, storage capacity and power supply capacity, at the same time need to deal with a large number of wireless sensor network node monitoring coverage data information and communication data, so in the process of covering monitoring in as far as possible under the premise of guarantee the network coverage to prolong the network lifetime, save network energy, is a key point in the research of wireless sensor network.In the traditional classic LEACH algorithm in wireless sensor network(WSN),the network cluster heads only considering the transmission of path and low consumption of energy, but did not consider the influence of network coverage performance. LEACH algorithm randomized to election cluster heads and randomized clustering at the same time,not using the polygon clustering considering cluster heads and cluster nodes in the network using the different coverage radius impact on network performance at the same time and the influence of dead nodes on the network performance. When a large number of nodes participate in work at the same time, will produce many redundant nodes and to work resulting in waste of energy network. In view of the above problems, this article in view of the LEACH algorithm to coverage-preserving improvement and sleep scheduling improvement, and proposed a coverage-preserving algorithm based on node death and radius of scheduling named LEACH_D_R, and in the coverage-preserving based on a LEACH sleep scheduling algorithm based on node information named LEACH_DR_ES.The two main innovations of this thesis are as follows:(1)This article proposed a coverage-preserving algorithm based on LEACH algorithm named LEACH_D_R,this algorithm build energy model first, introduce Voronoi polygon to clustering, each polygon is within a cluster. Due to bear the tasks of cluster heads is more,energy consumption is relatively larger, so in the choice of cluster head nodes need to optimize the random rotation selection mechanism, according to node type choose node coverage radius, cluster-heads increase its initial radius, decrease its initial coverage radius of cluster nodes, cluster heads optimized at the same time with considering the influence of the network of the death number of nodes in network cluster head election. When the cluster head node is about to run out of energy, make its Voronoi polygon mesh of the nearest distance neighbor node sends the message(if this cluster have no alive nodes, choose the node which have the nearest distance), makes it become the next temporary cluster headnode and waiting for next cluster head selection, cyclic scheduling in order to complete the task of data collection and transmission.(2)Used the nodes sleeping-scheduling mechanism, make use of a large number of nodes of the redundancy performance in the network. The network can be divided into several time round in each round time, the each time round can be divided into the awareness phase, the scheduling phase and the working phase three phases. The awareness phase was carried out on the network status and neighbor node awareness information. The scheduling phases make sleeping-scheduling, according to the network node redundancy properties, the node distance, node role properties and remained energy for threshold sleeping-scheduling condition to meet the requirements or threshold of nodes to sleep or awaked up. The work phase do network to communicate with each node state transition, then cycle scheduling.At the end of the paper, the proposed LEACH_D_R coverage-preserving algorithm and LEACH_DR_ES nodes sleeping-scheduling algorithms compared with LEACH algorithm for performance evaluation, including the number of network survival nodes and death nodes,the data transmission capacity, network lifetime, network number of cluster heads, network coverage and node energy consumption. According to the simulation experiment algorithm for network coverage has a strong performance, nodes sleep scheduling algorithm can save the network energy consumption, prolong network life time above 30%.