Research On Base Station Selection Method Of Ultra-wideband Indoor Positioning System

Global Navigation Satellite System(GNSS)basically meets various needs of location service in outdoor environment.Due to long-distance transmission and building shelter,the Satellite signal reaching indoor is very weak.So that it cannot provide reliable location service in an indoor environment.So that it cannot provide reliable location service in an indoor environment.With the increasing demand for indoor location service in people’s daily life and work,it is very important to study indoor location technology.This paper focuses on the research of Ultra-wideband(UWB)indoor positioning technology.The specific research contents are as follows:(1)Under the influence of Non Line of Sight(NLOS),multipath effect and physical measurement,the positioning accuracy of UWB positioning system decreases rapidly,and the output position coordinates fluctuate greatly.In order to improve the reliability and stability of UWB positioning system in Line of Sight(LOS)/NLOS hybrid scenarios,a UWB fingerprint positioning method based on Time Difference of Arrival(TDOA)combined with Base Station(BS)selection information is proposed.Firstly,the BS selection information of the fingerprint point is selected by using a three-step elimination BS selection method,and a fingerprint database is constructed after the TDOA information of the fingerprint point corresponds to the BS selection information.Then,the Improved Time Reversal Resonating Strength(ITRRS)formula is used to calculate the similarity between the test point and all the fingerprint points.Finally,in order to further improve the stability of the UWB positioning system,a noise suppression algorithm based on statistical filtering is used to filter the noise in TDOA data,and then Kalman Filter(KF)is used to smooth the output coordinates.In the LOS/NLOS hybrid positioning scene of 33m*5.1m*3.4m,the average horizontal error is 10.31 cm,the average vertical error is 2.72 cm,and the average threedimensional error is 11.04 cm.The method provides a feasible scheme for solving the problems of low positioning accuracy and large fluctuation of position coordinates in the indoor complex environment.(2)In order to judge whether the newly introduced BS can improve the positioning accuracy in the LOS scenario,a Position Dilution of Precision(PDOP)assisted BS selection method is proposed,which uses the Signal to Interference Ratio(SIR)and PDOP to weigh the newly introduced BS.If the decline rate of the PDOP is greater than the threshold λ after the BS is introduced,the new BS is used for positioning solution,otherwise,the original BS combination is used for positioning solution.In this paper,the PDOP assisted BS selectionmethod is used in the case of different initial BS numbers.In the LOS scene of33m*5.1m*3.4m,the experiment shows that: 1)when the initial number of BS is 5,the positioning accuracy obtained by using the PDOP assisted BS selection method is the highest;2)The three-dimensional positioning error of 12.06 cm is achieved,and the positioning accuracy is improved by 16.35% and 16.11% respectively compared with the case of all BSs participating in positioning and 5 BSs participating in positioning.In this paper,the PDOP assisted BS selection method is used to further improve the positioning accuracy of UWB positioning system in LOS scenarios.