Research On Variable Grid Coverage Control In Wireless Sensor Network

The thesis studies the variable grid coverage control technology for wireless sensor network(WSN). Because sensor nodes in WSN have limited size and energy and they are mostly deployed in complex and harsh environments, the energy efficiency and robustness of the network should be considered in the design of the sensor network, and we must reduce the energy consumption of the network and enhance the network's fault tolerance as much as possible. As one of the core technologies in wireless sensor network research, the main research goal of coverage control technology is to improve network energy efficiency and prolong the network lifetime under the premise of guaranteeing coverage quality,and meanwhile rationally allocate system resources, improve the quality of service (QoS) of WSN and accomplish the task of information-aware or data transmission better. In this work, we first introduce a complex network model in the study of WSN coverage control. By using the topology control strategy based on the complex network model, we can implement variable grid coverage for the sensing area, adaptively change the sensing intensity of the nodes, satisfy the upper layer application's demand and enhance energy efficiency and robustness of network simultaneously.Firstly, this dissertation reviews normal complex network models,especially focus on the small-world network model and the scale-free network model and analyze the mathematical characteristics and physical features. Then, a topology optimization strategy based on small-world model is proposed, in which by dividing the network into clusters and adding wired connections between cluster heads and sink nodes, a sensor network with small-world characteristics is constructed. Theoretical analysis and simulation results show that the strategy can reduce the average path length and prolong the lifetime of nodes in the network.After that, we propose a topology evolution algorithm based on scale-free network, where a wireless sensor network with scale-free characteristics is generated through the process of node growth and preferential connection between nodes. The analysis and simulation indicate the topology evolution algorithm is effective to ensure network coverage and enhance robustness to resist random errors and intentional attacks.Secondly, we propose a variable virtual grid coverage algorithm(VVGCA) combining with the idea of grid coverage and the topology control strategy based on complex network. This algorithm introduces the small-world and scale-free model in the topology construct part. At the same time, it completes regional grid division, cluster head selection in each grid node, topology evolution between the cluster head nodes and other processes. VVGCA achieves the goal of adaptively adjusting the grid size and the working node density according to the upper layer's sensing requirement and can improve energy efficiency and robustness while ensuring the coverage of the network.