Research On Indoor Positioning Technology Based On Bluetooth Low Energy 5.1

At present,the main indoor positioning technologies still have some problems.For instance,low accuracy of positioning,high consumption of power,high cost and weak anti-interference.In this thesis,the accuracy and power consumption of indoor positioning technology are studied.The method of indoor positioning based on Bluetooth Low Energy5.1 technology is proposed in this thesis.Compared with other indoor positioning technologies,Bluetooth Low Energy indoor positioning technology has relatively high accuracy.Its positioning accuracy can reach sub-meter level,and its power consumption is very low.Based on these,this thesis is mainly studied in the following three aspects.(1)In the process of indoor positioning,the array antennas not only receive signal of the tag,but also receive the multipath signals and other noise signals generated in the process of signals propagation.In this thesis,a weighted spatial smoothing algorithm is proposed to preprocess the data received from the array.And then a matrix decomposition algorithm is used to reconstruct the covariance matrix.The signal subspace and noise subspace are obtained by singular value decomposition of the covariance matrix.Finally,the spatial spectral function of the array is obtained by using the minimum norm method.The proposed algorithm combines the advantages of several algorithms.Results of simulation indicate that the improved algorithm has better estimation performance than spatial smoothing algorithm and weighted spatial smoothing algorithm for coherent signals.(2)A direction of arrival estimation system is designed and built,which uses uniform linear array to collect Bluetooth signal of tag and obtain a constant tone extension signal in Bluetooth signal.The constant tone extension signal contains In-phase/Quadrature data with signal direction Angle information.In-phase/Quadrature data is used to calculate the phase difference of the signal reaching the antenna array.Finally,the direction of arrival of the signal is calculated according to the phase difference.Gaussian filtering and mean filtering are used to filter the direction of arrival of the signal of estimation data.And more accurate the direction of arrival of the signal can be obtained after filtering.(3)An indoor positioning system based on Bluetooth Low Energy 5.1 technology is designed and deployed.Multiple locators are used to locate tags in the warehouse.The uniform planar array of each locator collects the tag’s Bluetooth signal.The signal contains the In-phase/Quadrature data of the position information of the tag.Then the direction of arrival and angle of pitch of the signal of the tag are calculated by using the In-phase/Quadrature data.Multiple locators are combined to obtain the direction of the signal to locate the specific coordinates of the tag.Statistical filtering and radius filtering are used to filter the coordinate data of the tag,so that the error of the position estimation of the label is smaller.