Research On Smartphone Based Indoor Positioning System In WIFI Networks

With development of wireless communication techniques and wireless positioning techniques, applications of indoor positioning are becoming more and more popular. Global Positioning System(GPS) technique has been widely used for outdoor positioning applications. However, it cannot be directly applied to indoor precise positioning because the received signal is too weak. In recent years, smartphone is widely used in people's daily life. Meanwhile, WIFI networks are also widely deployment in indoor environments. So, the research on smartphone based indoor positioning applications is meaningful because of wide coverage, low cost and so on.This dissertation includes two research aspects: the error reduction of indoor positioning and the indoor system design and implementation. First, we discuss the key factors of indoor environment that affects quality of indoor positioning. Second, we give the compression between the fingerprinting positioning method and triangle positioning method, and we discuss the reasons that cause the main errors of WIFI signal positioning. Finally, we proposed a modified the Kalman filtering algorithm, which could reduce the noise influence of received signal strength by removing the outlier values. Meanwhile, we also propose a correction weights triangle centroid algorithm, which could improve the proportion of different influencing factors in positioning results while guaranteeing the positioning accuracy.To implement our proposed indoor positioning algorithms, we also design and implement a real Android based system. First, we give the system requirement analysis. Second, we give the detail design of our system, which mainly includes data acquisition component, received signal analysis and de-noising processing component and so on. Finally, we present our system implementation in detail. The running result of our system shows it could obtain relative accuracy indoor positioning in our experiment indoor room.