Research On Wideband And High Precision Indoor Localization Technology

In the upsurge of the development of network information technology,the current society has entered an era of Internet of information sharing.Indoor localization technology plays an increasingly important role in production and life in the mature application of outdoor localization technology.However,the indoor multipath problem leads to the lack of indoor localization accuracy.In addition,due to the coverage and occlusion and other reasons,the anchor nodes need to be intensively deployed.The price and numbers of the anchor nodes cause high cost.Therefore,there is an urgent need to study the indoor localization technology with high coverage,low cost and high accuracy.The paper researches the indoor localization technology using WiFi antenna array signal to expand the coverage,reduce costs and improve accuracy.The main work of this paper is as follows:1.Indoor localization technology is faced with obstacles such as reflection,refraction and other issues of multipath,which leads to the lack of localization accuracy.The specific steps of the solution are as follows:the received signal is obtained from the WiFi antenna array or the channel state information(CSI)is got through channel estimation,which contains the angle of arrival(AOA)information for localization;the MUSIC algorithm is used to separate the multipath information from the CSI or received signal.Extraction of multipath AOA.The above process accurately extracts AOA information of each path and solves the problem of superposition interference of multipath effects.2.Aiming at the problem of identifying the direct path from the eigenvectors,an improved hierarchical clustering algorithm is proposed to effectively identify the direct path AOA information.AOA-based localization is optimized for the placement and orientation of the receiving antenna array algorithm.The results show that 75%of the test data error is less than 0.5 meters.3.Localization accuracy and cost constraints exist.In order to reduce costs,the paper proposes adjacent sub-carrier equivalent to the antenna array to ensure the localization accuracy while reducing the number of antenna arrays.Despite the reduction in the number of antennas,there is a problem that the phases of received signals between antennas are different.In view of the above problems,a calibration method of linear fitting is proposed.The imaginary part of the received signal and the CSI contains irregular phase information.The phase of one antenna is used as a reference,and the irregular phase of other antennas is fitted by piecewise linear fitting to eliminate the phase random deviation.The phase mismatch pairs impact of positioning accuracy.4.In order to reduce the cost,a localization target point-anchor node-server indoor localization prototype system has been realized.In order to improve the precision,a USRP X310 anchor and a HackRF device localization system has been realized.Design and implement the localization target point sending signal module,the anchor node receiving signal forwarded to the server module,sending and receiving signal module.Realize the software of the indoor localization computing,antenna calibration,results analysis and interface display and other functions.