Research On Coverage Optimization For Wireless Sensor Networks

A wireless sensor networks (WSN) is composed of a large number of low-cost, low-power sensor nodes which capable of sensing, processing and communicating and collaborate to form an ad-hoc network by the usual medium of wireless connection. The WSN achieve the observation and perception on the target or the environment by the sensing device in the sensor node. A fundamental issue in WSNs is the coverage problem, which can determine the scope of services provided by the network and great influence on the network cost and performance of specific applications. The coverage can be considered as a measure of the quality of service of WSN.Most of the time, data recorded from a wireless sensor only makes sense if correlated to a position. Sensor node localization of wireless sensor network is a key supporting technologies for many applications and is a prerequisite for many applications. The localization accuracy in wireless sensor networks is one of the key metric of performance.In this dissertation, the localization of sensor node and coverage optimization technology of network is research and discussion. This dissertation main discuss the range-free localization algorithm and the coverage optimization for static WSN and mobile WSN. The main works of this thesis are summarized as follows:(1)The original Monte Carlo localization algorithm is only suitable for dynamic wireless sensor networks, not suitable for static sensor network node localization. We improved the original Monte Carlo localization algorithm by introduction the virtual movement to the sensor node and the mobile anchors periodically issue their location information. The sensor nodes use the accumulated observations of mobile anchors to calculate its position. Simulation results show that localization accuracy is significantly improved.(2)The coverage quality of wireless sensor networks can be improved by take advantage of sensor node's mobility after initial random deployment. First, we present a redeployment scheme based on genetic algorithm to optimize the coverage quality of WSN. Then, when the optimal deployment position of sensor node is known, we proposed an assignment algorithm based on artificial immune algorithm to optimize the coverage quality of WSN. But the two algorithms are centralized algorithms, there are inevitable shortcomings of a centralized algorithm for this problem, we present a scheme based on co-evolution algorithm to optimize the coverage quality of WSN. Simulation results show that the proposed three algorithms can effectively improve the network coverage quality.(3)We study the coverage optimization problem for static wireless sensor networks. In some sensor network applications, high density of sensors is required for more data integrity in monitoring. As a result, there will be several overlapping areas appearing in the whole monitoring area. In the coverage problem, to have well monitored area, these overlapping areas are considered to be undesirable because they cause unnecessary energy consumption. For this reason, an approach called a cover set schedule is proposed to activate only a subset of sensor nodes. The subset are completely covered the targets. The bandwidth has a very important affectation on the cover set construction. We regard the bandwidth as the number of activities 1-hop neighbor nodes, and propose a method to select sensor node of cover set under the bandwidth constraint.Simulation results show that this method has better coverage quality.