Realization Of Code-decode And Data Verification In UHF RFID System Based On FPGA

Radio Frequency Identification (RFID) technology, which identifies target and obtains relevant information with non-contact, two-way data communication by radio frequency signal through space coupling. Because of a long communication distance of the Ultrahigh Frequency (UHF) Radio Frequency Identification system, there are several problems:channel attenuation, signal multipath interference and anti-collision of multi-tagscommunication etc. Therefor the reliability and security of the UHF RFID data transmission cannot be ensured, and seriously affect its large-scale commercial applications. Based on above reasons, it's of great significance to the research and improvement of UHF RFID data transmission, also has more practical application values.First, the design process of FPGA, Modelsim simulation environment are introduced. Second, this paper investigated the forward link and return link data encoding method in short range communication types A and B in ISO/IEC 18000-6, and deeply analyzes encoding method and technical parameters of Bi-Phase Space (FMO) coding, Manchester coding and Pulse Interval Encoding (PIE) coding. The paper also designed and simulated code circuits and decode circuits of the three encoding method by FPGA experiment platform. Third, the paper discussed the technical principle of error control of the UHF RFID system, especially for the technology of data verification and calibration, namely cyclic redundancy check that used in ISO/IEC 18000-6. The circuits of CRC based on Linear Feedback Shift Register (LSFR) are analyzed from theory and realization, and some means of solving problems are put forward, then an improved LSFR circuit to implement CRC is designed. For some require fast CRC calculation system, the paper designed a novel parallel CRC circuit by using recursive formula.All modules in this paper are simulated by modelsim and simulation results meet the ISO/IEC 18000-6 protocol's requirement.