The Design Of Baseband System Of UHF RFID Reader Based On Independent Standards

RFID(Radio Frequency Identification) technology is an automatic identification technology which can realize non-contact communication, and it’s also widely used in logistics, warehousing, transportation and other fields. The UHF(Ultra High Frequency) band RFID technology has many characteristics, relative to other band RFID technology, such as recognition distance and recognition speed which make it becomes the mainstream of the current RFID technology research. With the continuous development and improvement of UHF RFID technology, a variety of standard protocols including EPC has been improved steadily in the abroad, but our own country lacks a related unified standard protocols support which hinders the research and industrial development of the UHF RFID technology. In the year of 2013, China issued its first proprietary UHF RFID standard agreement "IT RFID 800/900MHz air interface protocol," which provided a strong technical support for the research and application of our correlation research units in the field of independent UHF RFID technology.Based on the study of the independent UHF RFID standard protocol, the baseband system of the UHF RFID reader in according with the independent standard protocol had been designed and implemented. The main contents include the hardware design of the reader’s baseband system, the design of software system and performance test of the baseband system, the design of hardware and software is divided into two parts which contains of logic control design and digital signal processing design.First of all, in the aspect of hardware design, since there is no one kind of integrated RF chip in according with the independent standard protocols to meet the performance requirements of the design, a digital baseband system program of MCU+FPGA design had been proposed. The MCU part is responsible for the logic control unit, and FPGA part is responsible for digital signal processing units of the baseband system. As the core of logic control unit, the MCU is responsible for the function realize of the protocol layer, application layer, the driving layer. This thesis had accomplished the design of the peripheral interfaces such as Ethernet interface circuit and USB circuit. The FPGA portion primarily responsible for digital signal processing of the baseband system, in terms of specific implementation, the design realized the DAC circuit of the forward link and ADC circuit of backward link. A method of discrete components construct had been used to complete the hardware design of the reader’s digital baseband part, which is the heavy and difficult points and innovation of the whole design, this approach has the advantages of design flexibility, scalability, and can realize low-cost applications.Secondly, in the aspect of the software system design, based on the analysis of the independent standard protocol, the software construct design of the logic control unit of the 32-bits MCU had been realized, which includes the normal communication between the reader and the tag, the reader and the PC. In the design of digital signal processing unit, a FPGA software architecture of transmit and receive links has been realized, which mainly contains the TPP coding unit and FMO decoding unit design of the forward link and backward link in according with the independent standard protocols. In the TPP coding part, based on a lookup table method to achieve the optimal state of the transmitting chain signal by minimizing the ISI, a rectangular wave shaped design had been used.Finally, in the aspect of system testing, this thesis analyzed the collected data through the joint test of the baseband system and RF system. This thesis also verified the justifiability of the software and hardware design by viewing the information of the communication between with tags and reader on the PC.