The Design And Implementation Of A WiFi-based Indoor Positioning System

Traditional GPS and other location technologies have been able to achieve high accuracy on meter level in outdoor environments. But for indoor environment, they can’t achieve that accuracy. With the popularity of WiFi technology and the increase of the WiFi coverage rate in past two years, the research on WiFi indoor positioning technology is also more and more in-depth. People developed more and more Indoor Positioning Algorithm. WiFi indoor positioning technology is become more commercial than research, and more and more Applications based on WiFi technology for mobile phone has been developed, and Location-based Services is developing rapidly. Against this background the author designed and developed a WiFi indoor positioning system based on Android platform.The main work of this thesis contains:(1) This thesis depth studied the indoor positioning technology based on WiFi Fingerprint Matching, and analyzed the effect of various factors that influence the WiFi signal. Then, proposed methods that improves the positioning accuracy and consummates the indoor positioning technology based on WiFi Fingerprint Matching.1) The first method is adding the Filter Method to the building of Fingerprint Database. By calculating the number of the AP at each collection point, we can decide which AP signal is unstable, so the unstable AP can be exclude. And then we can achieve the target to filter the data which collected before build the fingerprint database.2) The second method is adding the After Redress Method to the positioning section. With the acceleration sensor and the timer in the phone, the user can calculate the distance between the latest correct positioning result position and the current position. By compare the difference between the distance that the user moved and the distance of the two positioning point, we can know if the current positioning result is correct or not. Through this method the positioning system can do the redress of the final result.(2) The thesis designs and implements a WiFi Indoor Positioning System based on Android platform. The specific work of design and implement contains:1) The requirements analysis of the system;2) The data acquisition and analysis;3) The design and implement of the feature library of the system; 4) The design and implement of the position function.This indoor positioning system can be easily used in indoor places like:Large exhibition halls, shopping malls, hospitals. And provide users with accurate positioning services to help users save time looking for.