Design Of UHF RFID Reader And Research Of Anti-collision Method For RFID Tag Identification

RFID(Radio Frequency Identification) technology is capable of establishing contactless interconnection between the reader system and specific target tag through electromagnetic field coupling. Because it has the characteristics of fast recognition, large capacity of data transmission and storage and the tag can be reused in a variety of severe environments, RFID technology has been rapidly developed and its application has been widen little by little so that it was adopted to replace the bar code gradually in recent years. The applications of RFID technology in the library and archives management, alcohol anti-counterfeiting, livestock farming and meat tracing, asset tracking, logistics and supply chain management, motor vehicles management, clothing management and other fields have saved the cost and improved the operation and production efficiency greatly. For RFID technology, reader and tag anti-collision algorithm have been selected as the research focus. The UHF reader has been designed and the tag anti-collision algorithm has been further studied in this thesis.UHF reader is mainly composed of baseband processing section and RF transceiver section. In this thesis, STM32 and CC1101 have been selected to design the relevant reader module and the schematic design has been described in detail. The baseband processing section is designed with STM32 to control reader system and the RF transmitter section is designed with CC1101. The RF receiver part is designed with diodes and other discrete components. System frequency is in accordance with the UHF RFID frequency standards of the P.R. of China and The United States: 900-930 MHz, which has reduced the overall cost of UHF reader.The more electronic tag candidates are in the reader’s recognition space, the more serious the problem of data collisions during the recognition process are. Traditionally, ALOHA algorithm is used widely to resolve this problem. Here, the classification of tag anti-collision algorithm based on the ALOHA algorithm has been introduced firstly. Then, two Dynamic Frame-Slotted ALOHA algorithm proposed in recent years have been analyzed. However, they are generally not capable of achieving expected performance when the number of tag candidates is much larger or smaller than the initial frame size since they will easily produce much more unnecessary empty and collision slots in the process of the adjustment of Frame-size. To resolve this problem, a Rapid Dynamic Frame-Slotted ALOHA with interrupt mechanism method was brought forward which uses multiple multiplication factors(0.125≤N≤8) to accelerate the recognition process, reduce the collision and empty time slots and improve the system efficiency significantly. Simulation results indicate that the system efficiency can be increased up to 200% when the number of tag candidates is less than the initial frame size and the total recognition time is also reduced significantly when the number of tag candidates is more than it.