Research On Energy Efficient Coverage And Connectivity Algorithms In Wireless Sensor Networks

Along with the development of micro-sensor technology, wireless networks and embedded processing technology, wireless sensor networks (WSNs) attract more and more attention of researchers and it riches and makes easier life for the people. Coverage and connectivity problems constitute fundamental elements in WSNs, and they are also the key points to affect network performance and the quality of network service. Only making a certain level of coverage, the network can monitor the monitoring area in real time, therefore, the best coverage of the monitoring area could improve the quality of network service. WSNs are composed of many sensor nodes deployed in the monitoring area, and the nodes are limited in battery power capacities. Therefore, the effective energy usage is the key problem which needs to be solved under ensuring the quality of best coverage and connectivity.In order to tackle the problem above, this thesis analyzes the existing coverage and connectivity solutions in WSNs, and proposes a coverage control algorithm based on heterogeneous nodes. The network consists of two types of nodes which have different capabilities. For the normal-node deployment, we present a strategy based on node state transition; For the super-node deployment, we propose a strategy based on route table. A normal-node has three modes, namely, sleep, listen and active. A node redundancy mechanism is designed to check the redundancy of the sensor nodes, all of these make sure the better coverage of the network. By using the coordination of the two types of nodes, we provide both coverage and connectivity for the network. At last, the proposed algorithm is compared with other algorithms. Simulation results show that the proposed algorithm can extend the lifetime of the network when both algorithms have the equal initial energy.In this thesis, we also propose a coverage control algorithm which is location-independent. By adjusting its communication range and exchanging information with its neighbor nodes, sensor node can determine its own mode. At last, all the sensor nodes in active mode can cover all the targets and ensure the connectivity of network. Simulation results show that the proposed algorithm can not only ensure better coverage of the monitoring area, but also reduce the overall network energy consumption and extend the network lifetime.Whether the energy consumption is reasonable or not is an important index of the measurement of a coverage control algorithm in wireless sensor networks. The proposed two algorithms can make the coverage and connectivity of the network, and effectively improve the energy efficiency of the network, which will be valuable for other researchers designing related research and study.