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Research On Accurate Positioning Algorithms And Deviation Elimination Techniques Based On Time Delay Estimation

Posted on:2018-07-22Degree:MasterType:Thesis
Country:ChinaCandidate:W DuFull Text:PDF
GTID:2348330542452185Subject:Electronic and communication engineering
Abstract/Summary:PDF Full Text Request
With the development of information technology,target positioning technology is widely used,including surveillance systems,logistics,emergency rescue,resource management,property storage,etc.Measurement methods can be used to locate the target accurately,commonly including sonar,radar,mobile communications,multimedia technology,global positioning system,etc.The paper first introduces the principles of four measurement techniques,such as the arrival time of the signal,the time difference of the signal arrival time,the azimuth angle of the signal and the strength of the signal.Then the paper briefly analyzes the advantages and disadvantages of the four positioning techniques.The paper first establishes the mathematical model of positioning technology,then it carries on the follow-up research.In addition to the analysis of measurement techniques,the paper also analyzes various factors that produce the positioning error in detail.The basic principles of nonlinear least squares method and maximum likelihood method are applied to the time delay estimation in the paper.The paper proposes two precise positioning algorithms based on signal transmission delay,i.e.,the nonlinear least squares and maximum likelihood method.In addition,two-step positioning method can be obtained by the complicated formula derivation.The two-step positioning method transforms the nonlinear problem into a linear problem,and the target evaluation location can be updated by the non-correlation hypothesis and the correlation hypothesis.The paper employs Gauss-Newton iterative method and Newton-Raphson iteration method to solve the local minimum value in the process of calculating nonlinear least square method and maximum likelihood method.The paper uses computer software to simulate and analyze the influence of two iterative algorithms on the evaluation results according to the simulation results.In the unbiased estimation,the lower limit of the variance of unbiased estimator can be determined by the Cramer-Rao lower bound,which is an important reference factor in unbiased estimation.The Paper deduces and verifies the Cramer-Rao lower bound.The simulation of the Cramer-Rao lower bound of different signal-to-noise ratio provides a reference for the performance study of precise positioning algorithms based on signal transmission delay.In this paper,the nonlinear least squares method,the maximum likelihood method and the two-step positioning method are simulated by computer,then the position evaluation value of the target is obtained.According to the mean square error of the target evaluation value and the target real value,the performance of the three positioning algorithms is analyzed and compared.According to computer simulation results of mean square error under different signal-to-noise ratio and the mean square error of different number of receivers,the paper analyzes the influence of the SNR and the number of receivers on the performance of three positioning algorithms.In this paper,the structure of the cellular system is established by software,and the influence of the unit radius on the performance of the three positioning algorithms is studied.
Keywords/Search Tags:time of arrival, nonlinear least squares, maximum likelihood method, two-step positioning method, mean square error
PDF Full Text Request
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