Research On Indoor Fingerprint Positioning Based On CSI

With the popularity of smart mobile devices,location-based services have attracted more and more attention.Among them,Wi-Fi fingerprint positioning has become a key research content in the field of indoor positioning due to its low cost and wide application.Since the RSSI signal used in conventional fingerprint positioning is susceptible to multipath effects,the positioning error is increased.In recent years,as hardware devices begin to support the acquisition of channel state information in physical layer,CSI-based indoor positioning technology has gradually become a new research direction for indoor positioning.Based on the research of indoor positioning at home and abroad,this thesis compares the characteristics of RSSI with CSI.Aiming at the shortcomings of RSSI being affected by multipath propagation during wireless transmission,the advantages of applying CSI to fingerprint location are analyzed in this thesis.At the same time,this thesis applies Kriging interpolation to the stage of establishing a CSI fingerprint database.The fingerprint information collected is mainly estimated by interpolation,and the fingerprint information of the points between the collected data is obtained,and then the fingerprint database is established.This method can reduce the workload of establishing a fingerprint database without affecting the positioning accuracy,so as to improve work efficiency.In the positioning stage,this thesis proposes an improved WKNN positioning algorithm based on correlation coefficient,which uses a feature that the absolute value of the correlation coefficient between different nodes is closer to the correlation of 1 and calculates a new set of weights.The new weights are combined with the geometrical feature to estimate the initial position of the measured point,and then the average estimated position and the estimated position of the WKNN before the improvement are averaged,in order to reduce the positioning error.This thesis verifies the theoretical analysis by MATLAB simulation experiment.The verification uses the Kriging interpolation method to establish a fingerprint database,which can reduce the workload of offline data collection while ensuring the positioning accuracy.The experimental results show that the improved WKNN positioning algorithm can effectively reduce the error of indoor positioning.