Tham khảo tài liệu 'current trends and challenges in rfid part 16', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 440 Current Trends and Challenges in RFID Zetter K. 2006 . Hackers Clone E-Passports Available from http science discoveries news 2006 08 71521 currentPage 1 22 Tag Movement Direction Estimation Methods in an RFID Gate System Yoshinori Oikawa NEC TOKIN Corporation Japan 1. Introduction An RFID system is desired to be introduced in large gate management systems because it can read the ID of a large number of target objects simultaneously in the field of logistics and retail business. Especially UHF RFID has gathered significant interest since it has the advantage of long distance reading and low cost of tags. Customers using an RFID gate system require several convenient functions. One of them is to know the tag movement direction for the purpose of recognition in warehousing or shipment for inventory management. Moreover it can check for undesirable objects or prevent theft. For this purpose some sensors are established at the entrance and the exist side of the gate system in an existing system. Therefore the direction of movement of tags is judged by the time difference in the passing time at these sensors. For example the future store of the Metro group used this gate system for their stock management system of the backyard system 1 . However in these systems it is necessary to use optional expensive equipment such as several sensors. In this chapter an effective tag movement direction detection method is proposed in which an original tag communication system is used as much as possible without using optional equipment. 2. Estimation methods of the RF tag movement direction It is basically necessary for the judgment of tag movement to obtain two or more time information of an object. For obtaining that information it is common to use two sensors on both sides of the gate. This method corresponds to the Range-based method which is a location allocation system LAS method using a fixed anchor 2 3 4 5 . A conventional RFID gate system using .
