Research On Indoor Positioning Technology Based On Bluetooth Angle Estimation

With the development of wireless communication technology and the application of many intelligent products,indoor positioning technology has become a focused research topic at home and abroad.At present,the most commonly used indoor positioning methods are based on Received Signal Strength(RSS)and Angle of Arrival(AOA)but these positioning technologies require multiple access points(APs)for joint positioning.At the same time,the positioning accuracy is not high and practicability is also limited under specific conditions such as single AP which cannot be used for positioning.Aiming at the problem of high precision positioning in indoor environment,this thesis studies the indoor positioning technology based on AOA estimation of Bluetooth signal by taking advantages of low power consumption,low cost and miniaturization of Bluetooth.The research works are as follows:Firstly,this thesis studies the single-channel direction finding technology,and analyses two different single-channel direction finding methods in detail including: Watson-watt algorithm based on single-channel amplitude-comparisonand Doppler direction finding algorithm based on single antenna rotation.However,those algorithms have limitations.To solve these problems,this thesis designs a new method to improve the performance of single channel direction finding by using Bluetooth.The principle of direction finding is studied in detail and the advantages of the application of the system in indoor environment are aslo analysed by comparing with the existing positioning system.The time-sharing elimina t io n method and active correction method of array error are used,respectively,with the analysis of phase errros.A single-channel direction finding platform is built to verify the correctness of the proposed method.Secondly,the classical two-dimensional(2D)Multiple Signal Classfication(MUSIC)algorithm is studied in this thesis.There exists the problem of antenna mismatch in indoor positioning scene due to that the classical algorithm only estimates the parameters in the angle domain.Therefore,polarization array signal processing is introduced for indoor positioning system with the purpose of solving the problem of low accuracy of 2D MUSIC.In this thesis,the polarized MUSIC algorithm is optimized for fast dimensionality reduction and the performance of the proposed optimization algorithm is investigated.The results show that the complexity of the proposed algorithm is reduced with the consistent performance and the practicability of the system is improved.At the same time,the principle of geometric position relationship based on 2D angle positioning is demonstrated.In order to improve the positioning accuracy,the filtering algorithm is also applied and the simulation of the filtering the algorit hm is carried out.Finally,the test platform is set up for evaluating the proposed shceme in the open environment and indoor environment respectively.The experiment results show that the localization performance of the proposed algorithm is better than that of the classical MUSIC algorithm and the proposed systemcan achieve a high accuracy positioning with 90% of the positioning error of single station 0.7 meters meeting the indoor positioning needs.