The Research On Indoor Location Technology

In the modern society,the popularity of mobile intelligent terminals,and the rapid development of wireless network technology,making Location Based Services(LBS)very popular,its related applications demands showed a substantial growth trend.At present,LBS has rapidly developed and spread to social life in every field,it shows a good technical development prospects and a huge market space.For WiFi wireless networks,it is present in the indoor environment widely,its transmission rate is very fast,and easy erection,these advantages make it very suitable indoor positioning technology.The indoor positioning technology based on WiFi wireless network has the advantages of low cost,convenient operation and high positioning accuracy,which make it more popular than other positioning technologies.This thesis focuses on the study of WiFi indoor positioning technology based on wireless signal strength,and analysis the location of the fingerprint method used in the WiFi indoor positioning technology,aiming at the problem of the location of the fingerprint database in the phase of the establishment of the location fingerprint signal and the problem of the KNN matching algorithm,this thesis puts forward the method of re-screening and KNN+ matching algorithm,and solve the problem of database update.On the basis of the improvement,the indoor positioning system based on WiFi is designed and implemented,and test the positioning system,compare with the system with no improvement,the conclusion is that the positioning accuracy of the improved positioning system is optimized.The main contents of this thesis are as follows:(1)This thesis studied and improved the location fingerprint localization algorithm used in the positioning system.On the basis of experimental analysis of the external factors affecting the positioning,and point out the shortcomings of the location fingerprint algorithm.First,in the location fingerprint library setup phase,the position fingerprint method can not remove the useless wireless signal strength caused by external factors effectively,this thesis proposed a re-screening method to remove the distortion of the signal strength effectively.Secondly,in the positioning phase,the KNN(k-Nearest Neighbor)position matching algorithm used to calculate the positioning accuracy error is too large and unstable,this thesis proposed KNN+algorithm based on KNN matching algorithm.The KNN+ algorithm takes full account of the influences of each reference point on the position of the point to be measured,gives a different parameter to each reference point,the KNN+ algorithm can reduce the positioning error effectively,it also solves the problem of updating the database due to the change of indoor environment.(2)This thesis designs and implements the WiFi-based indoor positioning system based on the improvements,designs and implements the various function modules of the server and client,including positioning module,positioning display module,login module and client module.This thesis testes the positioning system in the indoor and outdoor environment,compares of positioning accuracy before and after improvement under the same test conditions,and analysis the test results.The experimental results show that the improved method can effectively improve the positioning performance of the system,and can eliminate the impact of the external environment on the positioning error effectively.The system can achieve a stable positioning effect,and positioning accuracy has improved greatly also.