| The Radio Frequency Identification (RFID) is a new generation non-touching automatic identification technology for supporting an automatic tracking and identification of an item in the ubiquitous computing environment. RFID system is composed of readers and tags, transmitting data through radio frequency. As a promising technology, RFID has been widely applied in social, economic, national defence and many other fields over the past years.The thesis focuses on the anti-collision algorithm in RFID system. At the beginning, it introduces the basic principle of RFID systems, and raises the significance of rearch on anti-collision algorithms through the knowledge which related to RFID. Then it introduces the current tag anti-collision algorithms which are mainly separated into ALOHA-based algorithms and binary-based algorithms. In the ALOHA-based algorithms, the thesis introduces pure ALOHA algorithm, slotted ALOHA algorithm, framed slotted ALOHA algorithm and dynamic framed slotted ALOHA algorithm. In the binary-based algorithms, it introduces the binary tree algorithm, the query tree algorithm, the binary search algorithm and its improved algorithms—the dynamic binary algorithm and the back off index algorithm. The thesis gives the example of each algorithm and analysis each performance. In the end, the thesis proposes a new improved anti-collision algorithm which combined the advantages of the ALOHA algorithm and the advantages of the query tree algorithm. The new algorithm overcome the disadvantage of ALOHA which may can not identify a tag in a specified time, duo to it's characteristic of random access. On the other hand, the new algorithm also use the grouping function to reduce the height of the query tree when the number of tags is large, which brings lower identification delay. The thesis gives the principle of the new algorithm. Through the features compared, we can find the new proposed algorithm is more effective than others introduced. |
