Research And Implementation Of WiFi Indoor Positioning System Based On Location Fingerprint

With the rapid development of Internet technology and the popularization of smart phones,the location service provided by GNSS has brought great convenience to people's lives.However,in the indoor environment,the location services provided by GNSS cannot meet the needs of users due to the obstruction of buildings and the complex indoor environment.Therefore,there is an urgent need for a technology that can provide high-precision location services in an indoor environment.WiFi-based indoor positioning technology has the advantages of low cost,high accuracy,and good robustness.Due to these advantages,WiFi-based positioning technology has become a hot spot in the current indoor positioning technology research.This thesis systematically researched WiFi location technology based on location fingerprint,and the main work is as follows:(1)The influence of distance,time and terminal orientation on the RSSI signal is analyzed,and the construction scheme of multi-orientation location fingerprint database is determined.Then,the RSSI preprocessing scheme is determined by analyzing the advantages and disadvantages of the mean filtering algorithm,Gaussian filtering algorithm and Kalman filtering algorithm.(2)By studying the law of Probe Request frames sent by intelligent terminal devices,this thesis introduces a concept of multi-sampling.Under the experimental environment,the traditional KNN algorithm has no significant improvement in positioning performance under multi-sampling conditions.By analyzing the complementary relationship between Spearman correlation coefficient and Euclidean distance,this thesis proposes an improved KNN algorithm that incorporates Spearman correlation coefficient.Compared with other algorithms,this algorithm has a significant improvement in positioning accuracy and stability.(3)At the end of this thesis,a WiFi indoor positioning system based on location fingerprint is designed and implemented.This thesis analyzes the limitations of the traditional KNN algorithm,proposes an improved algorithm,and finally achieves a WiFi indoor system based on location fingerprints.Experimental results show that the proposed positioning algorithm has higher positioning accuracy and stability than traditional schemes.Therefore,the improved algorithm has certain reference value for the research of WiFi indoor positioning based on location fingerprint.In addition,the WiFi indoor positioning system implemented in this paper can run stably and respond quickly,which has certain value in promotion and application.