Localization Of Sound Energy Intensity-based Wireless Sensor Network Target

Target localization based on acoustic energy strength in wireless sensor network, researched for in this dissertation, doesn't need accurate time synchronization compared with target localization based on time difference of arrival, and doesn't need high cost of sensor array compared with target localization based on angle of arrival, and doesn't need large number or high density of nodes compared with target localization not based on distance such as centroid position. It can finish the localization quickly and accurately using detected acoustic energy values of few nodes, as well as reducing the energy consumption of nodes and demand for wireless communication bandwidth.Firstly, acoustic propagation characteristic is analyzed in the dissertation. Based on law of acoustic propagation, the relationship between acoustic energy strength and distance from target to node is found, then acoustic energy attenuation model is proposed. Basic target localization algorithms are introduced based on the model, including maximum-likelihood (ML) algorithm, nonlinear least-squares(NLS) algorithm, linear least-squares algorithm(LS) and energy-position united linear least-squares(ULS) algorithm compromising advantages of others.After analyzing the estimation error of basic target localization algorithms, making weighting coefficient be the inverse of the noise covariance, algorithms are improved through introducing weighting matrix. Consequently the weighted nonlinear least-squares(WNLS) algorithm, weighted linear least-squares(WLS) algorithm and weighted united linear least-squares(WULS) are given, whose localization accuracy are much better than non-weighted algorithms. Then starting from number of nodes and equations involved in localization, reducing twice is proposed, which reducing the complexity of algorithm, the running time of localization and the energy consumption of nodes, extending the life span of the network nodes in the premise of ensuring the localization accuracy.Lastly, based on the platform of MATLAB, simulations are conducted for the above-mentioned target algorithms and improvements. By comparing and analyzing, the feasibility and effectiveness of the algorithms and improvements are well verified.