The Public Security System Based On The Design And Implementation Of Android Wifi Indoor Positioning System

With the development of mobile technology, people show more and more interest in mobile terminal positioning technology. Mobile base station, GPS make outdoor positioning technology widely used and begin to play an increasingly important role in people’s lives. In the room, because of the barrier of walls, the accuracy of the positioning terminal sharply declines, let alone a region positioned inside the building.Commonly used indoor positioning techniques such as infrared, ultrasound, Bluetooth, etc. require additional deployment of a large number of hardware devices. In recent years, wireless LAN technology gained rapid development, and due to its powerful features and convenience, it has been widely used in people’s daily life. Because of the prevalence of wireless LANs, people began to attach the importance of wireless LAN applications in indoor positioning. Positioning in Public security system described in this article is based on the 802.11 b wireless network.This thesis presents the design of the system based on the basic idea of Wi-Fi positioning. The main idea of the system is to determine the mobile device’s position according to its Wi-Fi fingerprint location. First, the system registers the information of each indoor AP(wireless access point); second, it uses some mobile devices to collect each AP’s RSSI(signal strength) at multiple points indoors as a fingerprint of that point, which we call Wi-Fi fingerprints; third, it stores Wi-Fi fingerprints and corresponding location information into the server; finally, when one mobile device needs to be positioned, it collects Wi-Fi fingerprint around it, and uploads them to the server, then the server determines the region where the mobile device is located according to the data previously collected.According to design of this system, we implement the indoor wireless positioning system. The system consists of client and server in two parts. The program of the server-side is developed under Windows platform, with multi-process technology, which can store Wi-Fi fingerprint of pre-collection points, and judge the position of mobile device. The client is developed on the Android platform, which can collect Wi-Fi fingerprint data, interact with server, and show the result. Android system is used to ensure the positioning system can be widely used.In order to be able to visually know the effectiveness of the software, we test the system in one office which owns enough APs. First, we register all APs’ information on one floor; then, we deploy many data collection devices in every room, and collect enough AP information; finally, we try to position the mobile device at many places of every room. The test results show that the positioning system can accurately locate the position of the mobile device, so the system shows a good practicability.