Research Of Indoor Positioning System Wifi-based Technology

With the popularity of wireless network technology and the rapid development of multimedia technology, location-based services gradually go into the public’s attention, and become a hot spot of research. The development mode of location-based services is diversified, therefore, people’s digital life gradually becomes more and more rich and colorful. For example, public scoring web is a typical representative of the life services of searching the surroundings.There are two key factors for location-based services. One is positioning, and the other one is the value-added service,but the foundation to provide related services is to determine the location.The earliest research of wireless positioning technology dated back to the automatic vehicle location (AVL) system in 1960s, moreover, the United States FCC published E-911 positioning standard in 1996, which pushed a research climax. But with the rapid development of wireless communication technology and the gradually improvement of the life quality,the demands of indoor positioning for people were increasing.However, the outdoor positioning technologies were difficult to apply to the indoor environment, and the positioning accuracy was not up to the standard, therefore, people began to study indoor wireless positioning technology in the end of the 1990s.So far, the research of indoor positioning focus primarily on the study of indoor location positioning technologies and indoor positioning algorithms, in essence, the final purpose of research is that how to improve the positioning accuracy. In this paper, because the research of WiFi-based positioning technology can utilize existing infrastructure, and additional hardware devices do not need to be added, moreover, the cost is relatively small. Subjected to conditions, this paper presents the study of the WiFi-based indoor positioning system.The application scenario of system is the supermarket environment. In this paper, the RSSI ranging method is adopted to get the distance between AP and mobile node, and trilateration approach is adopted to gain the location of mobile node. To improve the positioning accuracy this paper presents a filtering mechanism and the location compensation mechanism, and using the NS2 simulation software verify the effect of the two mechanisms.Experimental results show that, to a certain extent, the filtering mechanism and the location compensation mechanism can reduce the error. In the end, an idea that choosing the three best APs to improve the positioning accuracy when receiving many signal strengths from the APs, is put forward.