A Study On The Key Techniques Of Localization System In Underwater Acoustic Networks

Localization is the basic issue of the underwater applications and security monitoring.However,the traditional one-node localization system has a large positioning error and can not satisfy the reqirment in this era.Hence,It is improtant to have a research on the localization algorithms based on underwater acoustic networks(UANs)to improve the performance.UANs have some characteristics such as large scale,low bandwidth,low transmission rate,less anchor,limited power and difting with ocean current which bring challenge on the realization of localization.The thesis focuses on the localization algorithms research for UANs on the basis of the characieristics described above to increase the localization accuracy,reduce the communication cost and enhance the robustness etc.The research achievements and Innovative Pionts are as follows:1.The thesis proposed a double rate self-localzaiton algorithm based on information theory for multi-hop UANs(DRP).The algorithm increases the ranging and localization accuracy,meanwhile needs less anchor,limited power and bandwidth,which performs well in underwater environment.By analyzing the effection of reference nodes topology and ranging error on the localization peformance,The thesis also proposed an optimized reference nodes selection scheme which increase the loclaization accuracy further.2.For mobile UANs with drifting nodes,the thesis proposed a prediction-based localiation algorithm for mobile UANs.The algorithm present a mobile UANs model and a hierarchical strategy by analyzing the effection of ocean curent and storm on localization performance.Then,the algorithm predicted the mobile nodes' position using the ranging information.The algorithm increases the localization accuracy in mobile networks and sloves the less achor problem in UANs.3.The thesis proposed a fast initialization method for UANs.The method can accomplish the localization and sychornization at the same time with less anchor and present a time slot allocation strategy based on TDMA protocol to decrease the probability of message collision and reduce the energy consumption causing by retransmission.The proposed initialization method not only has a high accuracy,but also reduce the initilization time delay and communication traffic which increases the distribution efficiency of UANs.4.The thesis proposed a TDOA-based target localization algorithm by minimizing the module of noise vector.The algorithm constraints the measurement error and self-localization error of UANs on the target localization which increases the target localization accuracy and enhence the robustness.5.The thesis constructed a UANs system with 1 anchor and 4 ordinary nodes,did 4 experiments in anechoic tank laboratory,including ranging experiment,self-loclaization experiment,initialization experiment and traget localization experiment.The experimetal results are accordant with that of simulation which verify the effectiveness of algoritms proposed in the thesis.