Study On The Positioning Of RFID Tags

Radio Frequency Identification (RFID), is a generic term for the technology using radio waves to automatically identify individual items and collect associated information. Of late years, with the promoting of RFID technology, identification target location is needed with essential accuracy in several RFID occasions such as indoor or narrow space environment. As to RFID indoor location, it is very important to study location algorithms with high accuracy because of the influence of serious multi-path and NLOS error in indoor environment. And as to the location of identification target in narrow space, varying location technology is needed. In this article, UHF-RFID and HF- RFID location technology is studied according to the two occasions above.As to UHF-RFID indoor location, according to the problem that TOA location algorithm based on time-of-arrival is sometimes not available when signals are hold up by the objects in indoor environment, we introduce improving Monte Carlo location algorithm based on the kernel ideal of sampling into keeping track of tag in RFID indoor location system and analyze the influence of ranging error, the number of samples and tag stop while moving. Simulation results show that the proposed algorithm is non-sensitive to ranging error and the number of samples. When TOA is not available, or when the tag stop while moving, traditional Monte Carlo is not available, but the proposed algorithm still keep track of tag accurately. Secondly, from practical point of view, we analyze the influence of a number of environmental factors, such as antenna polarization mismatch, signal noise ratio, construction material on the RFID indoor location system.In order to locating identification target in narrow space, RFID systems more work on HF frequency. In this article, for example of locating medicine RFID tag in jungle medicine box, HF-RFID several antenna space division location algorithm in dense multilayer environment is studied based on shutting off layers one after another. What is more, the project of space division location of medicine in jungle medicine box is introduced. The reader have its several antennas perambulated is demonstrated. According to the problem that the influence of tag antenna on HF antenna coil due to many layers and narrow layer-interval in medicine box, the design and experimentation of reader antenna coil is carried out. With developing of showpiece of RFID medicine box system, we prove its availability preliminarily.