Indoor Positioning Method And Application Based On WiFi Fingerprint And QR Code

As communication-related infrastructure becomes more and more complete,location-based services are used more and more frequently.In outdoor location-based services,it mainly relies on global satellite navigation systems and assists positioning with the help of wireless cellular networks.However,indoors,most areas cannot receive strong enough satellite signals for positioning,which makes indoor positioning technology have broad development prospects.Among many indoor positioning technologies,WiFi positioning technology has the lowest deployment cost and promotion cost,and positioning accuracy can meet general commercial needs.Therefore,a large number of academic institutions have conducted research on WiFi positioning in indoor positioning.The indoor environment is relatively complicated,and the wireless signals emitted by WiFi devices are easily affected by various factors,which brings a huge test to the research of positioning based on WiFi technology.With the development of smart phones,many researchers have begun to study the combination of various sensors on the phone with WiFi positioning technology.This paper selects WiFi technology for research,and combines QR code technology with WiFi technology to achieve the purpose of improving the positioning accuracy of the system.Finally,the method is integrated into the designed positioning system.The work content of this paper is as follows:First,the propagation characteristics of WiFi signals and the interference factors of WiFi signals are studied and analyzed.In order to understand the propagation characteristics of WiFi more directly,this article designed 7 sets of experiments to reflect the relationship between WiFi signal and space,time,device posture,and human body from the data level.After research,it is found that directional factors need to be considered in the process of collecting WiFi signals,and in view of the phenomenon that WiFi signals are found to be unstable,a quartile method is proposed to process the collected original WiFi signal data,using processed and unprocessed data.The fingerprint database constructed with the data of,was analyzed by the positioning comparison experiment,and finally found that the use of the quartile method to process the original data reduced the average positioning error by 12.2%.Then the traditional positioning algorithm is researched.Traditional positioning algorithms mainly include K-nearest neighbor algorithm and weighted K-nearest neighbor algorithm.In the traditional positioning algorithm,the K value is used as a variable,and the positioning accuracy is different when different K values are used.Therefore,in the experimental environment built in this article,the relationship between the K value and the positioning accuracy is studied,and finally the article built The optimal value of K is 4 under the experimental conditions.The experimental analysis of the relationship between the number of wireless transmitting devices and the positioning effect is carried out,and finally it is concluded that as the number of APs increases,the average positioning error decreases,but the decreasing speed gradually decreases.The experimental analysis of the relationship between the deployment density of reference points and the positioning effect is carried out.Finally,the experimental results show that too high or too low reference point density will reduce the positioning accuracy.In view of the high time complexity of the traditional algorithm,a BFS-WKNN algorithm is proposed to reduce the time complexity of the traditional WKNN algorithm.Finally,the experiment shows that with the increase of the calculation scale,the running time of the traditional algorithm increases linearly.,While the running time of the BFSWKNN algorithm remains stable.Aiming at the problem of insufficient positioning accuracy,this paper uses the camera sensor on the smart device to combine QR code technology with WiFi positioning technology.After experimental analysis,this combined method reduces the average positioning error by 13.3%.Finally,according to the actual needs of the entire positioning process,a prototype positioning system was designed based on the Android platform,which realized the functions of fingerprint collection,QR code import,database display and positioning display,and detailed description of the specific implementation method of the prototype system.Finally,relying on the verification platform,real-time evaluation and verification of the relevant research content of the subject proved the practicability of the system.