Indoor Positioning Techniques Based On WLAN

In the mobile Internet, the location-based service is the highest frequency of use, one of the most widely used service application, and many other mobile applications are used directly or indirectly to LBS. By means of a global satellite positioning system, such as in outdoor open spaces, LBS has been able to provide users with high-precis ion, high stability location services, its application has been infiltrated into various industries and the mass market. However, indoor places more activity in humans, due to the building block and so on; the received satellite signals are often distorted, and thus can not accurately measure the exact position of the target in the indoor place through a satellite positioning system. Therefore, the study environment for indoor positioning technology, the development of one of the focus areas of mobile computing industry positioning system users and popular application requirements are met. Research work of this paper is in IEEE802.11wireless local area networks in recent years, the rapid development of technology and the promotion of a wide range of backgrounds, combined with mobile computing needs new positioning technology, location-based services, such as on arising.In this paper, this time based on measured indoor positioning technology for a more in-depth study of the system, analyze and synthesize the key factors affecting the accuracy of positioning against, and the corresponding solutions. By comparison algorithm and experimental analysis proves the effectiveness and feasibility of the program. The main point of the paper work and innovation as follows:(1) Research asynchronous pseudorange differential based indoor positioning methods. In this paper, based on the distance difference between the round-trip time measurement, round trip time method (RTT) measurements to locate the target terminal sends a request to the total cycle time signal processing returns through the access point, thus avoiding the need for clock synchronization. While using pseudorange differential method can reduce the spread of the way near the access point due to interference caused by homologous suffered measurement bias.(2) Round-trip time measured based on delay system processing algorithms. Conventional systems often use a pre-determined time delay method to obtain the measured value, after the positioning of use; the system follows the process previously measured time delay. Feature of this method is that the delay in the preliminary measurement remains unchanged after use can not be changed in real time. The methods described herein will pass signals at each end of the start time to the access point; the signal is passed back to the timing data package to the destination terminal, returned along with other information, the terminal based on the real-time measurement results received to calculate the position, having a high positioning accuracy.(3) In this paper, the Gaussian "background" way to measure the results of the model to achieve adaptive dynamic environment. This paper proposes a "background" modeling approach to solve the adaptive changes in the measured data selection:The process begins with the first paragraph of positioning statistics results as a "backdrop",’background" for the collection of valid statistics. Since the mobile terminal in the indoor premises of the process is usually slow linear change when the environment changes the active short,"background" will remain unchanged, and when the environment changes or prolonged passive changed, the’New Setting"(New test results) into a linear "background", the formation of a new "background" data, the positioning process is based on the "background" data to measure the position of the terminal.(4) This article will coordinate research-based approach to optimize the positioning height horizontal positioning results. Activities indoors under most circumstances are within the target discrete flat space, height values stabilized, often highly value the floor within1-2meters. There Based on this, we propose a horizontal positioning to optimize the results based on height error method, the results of multiple measurements statistics evaluated further removed a large height deviation measurement results in order to achieve the purpose of optimizing the test data.(5) This paper will examine ways to achieve a weighted voting positioning signal in real time to select the access point. This article will examine ways to achieve a real-time weighted voting to select the access point, the basic principle is to select the signal propagation on the way, the interference suffered the same two adjacent access points, using the method of this paper is calculated from the difference between the signal propagation distance difference, as far as possible to ensure removal of signal propagation pathway homologous errors. The main method of weighted voting is used to determine the access point "near" level.