WiFi-Based Indoor And Outdoor Positioning

As the Internet and Communication technologies continue to increase,particularly mobile smartphone,the demand for location-based services are growing.GPS can provide better positioning experience in open areas,but the positioning result is not satisfying in the room or obstruction region where GPS signals block seriously.Some researchers and institutes have developed the positioning system used in such conditions,mainly via IR,Bluetooth,RFID,UWB,WIFI,short-range wireless communications technology.Wireless positioning technology based on WFI has attracted much attention due to widespread deployment of access points and low cost.WIFI positioning system is through measuring the received signal strength to build the fingerprint map.The key values of the fingerprint map mainly include the SSID of the access points or the MAC address,the signal strength value,reference point coordinates.In the process of positioning,the system needs to compare the current signal with the database and this might take a lot of time and bring in error.This paper introduced a fingerprint algorithm based on ranging.The signal dissemination models indoor and outdoor are mainly studied,the characters were analyzed and auto-adapted model were proposed.The overall situation searching was avoided in the fingerprint localization process,but only searched the data scope where mobile phone occupied to reduce the computation load and the localization time.This article also proposed a concept that search the database signal intensity value data with bunch of width.This system was realized in the Android platform composed by the Android handset client and the localization server.The offline database gathering,document uploading and downloading,matching and demonstration were realized in the app.The data training,online database matching,demonstration could also be operated on Matlab.Test were carried and analyzed on inside and outside the room under different parameter conditions.