Research And Implementation Of RFID Indoor Positioning Technology Based On Doppler Effect

Positioning technology has provided convenience for human live.Nowadays there are many location based services, such as navigation andlocation based recommendation. Most of these services are based on GPS,which cannot work indoor. Indoor positioning technology is required todeliver these services indoors. Compared with outdoor environment,indoor environment is more complicated and changeable. Therequirement for the accuracy is higher. Until now, there still exists indoorpositioning technology which is widely used commercially. Furtherresearch is required to improve indoor positioning technology.In this paper, the analysis and research of RFID indoor positioningtechnology is performed, and a RFID indoor positioning technologybased on Doppler Effect is proposed. Using a moving antenna, theposition of tagged item can be calculated. This paper designed the methodto calculate the relative between tag and antenna. The direction of tag canbe calculated based on resolution of velocity vector.The main research work is as follows:(1) This paper designed triangulation based on RFID system. Thedirection from tag to the antenna is calculated based on the direction ofsignal propagation to the antenna.(2) Through researching Doppler Effect in RFID system, this paperdesigned the method to calculate the relative between tag and antennabased on Doppler shift.(3) Positioning based on the rotation of antenna is proposed in thispaper. The RFID antenna is fixed at the edge of rotary platform. Thismeans the antenna can rotate at the same angular velocity as the platform.Due to the motion of rotary platform, theoretically the Doppler frequencyvaries periodically. Direction and range of target tag can be estimatedthrough analyzing the movement between antenna and tag. (4) A novel positioning method using IMU is proposed. With thesensor data from IMU, which is attached to the antenna, the movement ofantenna can be recorded. The position of the target is evaluated withrespect to the movement data.The structure of this paper is organized as follows. Firstly, we statethe background of the research. Secondly, we summarize the RFID indoorpositioning technologies and analyze the challenges encountered. Thirdly,the design and principle of positioning method are proposed. Finally, theexperimental results and the analysis based on them are presented.