Research On Mobile Network Based Nlos Error Compensation And Key Positioncalculating Technology

As an emerging strategic industry,location based service is more and more prosperous,it has been widely used in fields such as intelligent transportation,staff scheduling,logistics distribution,security monitoring and traveling,etc.Positioning technology based on mobile base station network has received significant attention of numerous universities and research institutions.This dissertation is part of the national high technology research and development plan "The demonstration of key technology and service on indoor and outdoor high precision navigation and positioning",conducting in-depth research on the propagation path and coverage of the ranging signal,the NLOS(Non Line of Sight)error compensation of TDOA(Time Difference of Arrival)as well as position calculating algorithm.The main contents of this dissertation are as follows:The first one is the research on signal propagation path,this dissertation has set up a surface based signal propagation path model and a point based signal propagation path model.Surface based model is used to get the LOS(Line of Sight)transmission of the signal,by combining with the actual measured data,we can better possess the signal propagation in positioning areas.While point based model is used to get the value of TDOA on each specified point,by comparing with the measured data,we can study the LOS and NLOS transmission of the signal,as well as correcting the error of the measured data,and provide revised plans for the acquisition and processing of feature points.The second one is the research on NLOS error compensation,this dissertation put forward a kind of NLOS error compensation scheme based on weights,and proposed three weighting schemes which are suitable for different situations.The aim is to get the NLOS error of the positioning term in also as to reconstruct its LOS(Line of Sight)TDOA.Those weighting scheme are the Euclidean distance weighting scheme,the average weighting scheme and the single feature point scheme.This dissertation worked out a self-adaptive selecting mechanism to choose which weighting scheme to use when in different situations.The third one is research on NLOS error compensation based position calculating algorithm,this dissertation proposed an algorithm which use the LOS TDOAs of the positioning terminal as the already known parameters.We can get the coordinates of the mobile terminal by means of solving the positioning equations,in the calculating process,this algorithm use the differential calculus to linearize the positioning equations,the LS(Least Square Method)to get the generalized inverse matrix,and the loop iteration to find the optimal result.At last this dissertation give the simulation analysis and field measurement,and the field measurement shows that the positioning calculating algorithm has achieved a meter level positioning precision.