Research On Indoor Positioning Method Based On WiFi

With the rapid development of Internet and mobile technology, the demand for information and services has increased significantly and research on indoor LBS(Location Based Service) has gained a lot of attention. Although GPS positioning system has a high positioning accuracy in the outdoor environment, it is difficult to meet the needs of the object localization in indoor environment as indoor localization is more challenging than outdoor localization due to its complex ambient influences, such as the signal shadowing and multipath effect. A Great number of technologies such as Ultrasonic, infrared, radio frequency have applied to address the indoor localization, but each of them has flaws, highly cost or easily affected by multipath effect that they can not obtain better accuracy. So we extract the channel state information features and apply it to the research of the intrusion detection, location identification and trajectory tracking problems. The main contributions of this paper are as follows:1. We propoded a design for device-fee human intrusion detection based on the correlation of CSI amplitude in different scene. First we extract the CSI feature in the static environment. And in the detection phase, calculate the correlation coefficient between the static feature and the real-time feature. Then we can know whether there is intrusion behavior according to the correlation coefficient. Experimental results show that the multi-carrier amplitude matching method can achieve higher detection rate.2. Through the analysis on block feature of the signal propagation path, we design a device-fee location identification method based on signal block. We record the block feature of the signal propagation path at different distance between the transmitter and the receiver and finally we can obtain a better positioning result.3. We further propose a trajectory revise method via phase difference. Calculating the phase difference of two adjacent antennas to identify the target direction. By integrated multiple sets of antenna direction, we can revise the trajectory of the target.