Analysis of related research on UHF RFID air interface protocol

The air interface communication protocol specification is the information exchange between RFID Readers and RFID electronic tags, which is to realize the interconnection and interoperability between the production equipment of different manufacturers. The air interface protocol ISO 18000-6 of UHF RFID technology is basically a specification that integrates the product specifications of some existing RFID manufacturers and the label architecture requirements proposed by EAV-UCC. The air interface protocol includes the physical layer and the media Access Control (MAC) layer. The physical layer includes data frame structure definition, adjustment/demodulation, encoding/decoding, link timing, etc., with no restrictions on data content and data structure.

The current UHF RFID air interface protocols are mainly ISO 18000-6B protocol and EPC C1GEN2 protocol (EPC C1GEN2 protocol, now ISO 18000-6C protocol). Generally speaking, the definition of ISO 18000-6C protocol is more complete, and the existing products basically follow this protocol.

In the EPC protocol, the RFID reader obtains tag information by sending an unmodulated RF carrier and listening to the tag's backscattered reply. Tags transmit information by backscatter-modulating the amplitude or phase of an RF carrier.

EPCglobal certification testing includes conformance testing to ensure that RFID products comply with the UHF Gen2 standard and interoperability testing to ensure that all aspects of the reader interface are properly designed to seamlessly interoperate with other Gen2 certified products. While most passive RFID tags use the energy of the RFID reader signal to power the tag's integrated circuit (IC) and backscatter it toward the reader, BAP tags use an integrated power source (usually a battery) to power the IC, All the captured energy of the reader is thus available for backscattering.

Under the G2 standard, users can hide all, some, or untagged memory. Depending on the access rights of the interrogator and its proximity to the tag, the interrogator's ability to access or modify tag data varies. This prevents tag data from being stolen or tampered with. The G2 standard also establishes an anti-counterfeiting measure involving cryptographic authentication labels. The UHF Gen2 V1 tag sends a static reply back to the reader, making it easy for cloning to create counterfeit tags. Under the G2 standard, each time a reader sends a signal to a tag, it sends a different secret number, and the tag computes a reply specific to that interaction.

Those RFID standards related to the air interface protocol

ISO/IEC 18000-1 Information technology: Radio frequency identification for item management - Reference structure and standardized parameter definitions. It regulates the communication parameter table of the reader and tag, the basic rules of intellectual property rights, etc. that are commonly observed in the air interface communication protocol. In this way, the standards corresponding to each frequency band do not need to repeatedly specify the same content.

ISO/IEC 18000-2 Information Technology: Radio Frequency Identification for Single Product Management - Suitable for intermediate frequency 125 ~ 134KHz, specifying the physical interface for communication between the tag and the reader, the reader should have the same type as Type A (FDX) and Type B(HDX) Capability of tag communication; specify protocol and command plus anti-collision method of multi-tag communication.

ISO/IEC 18000-3 Information Technology: Radio Frequency Identification for Item Management - Applicable to the high frequency band 13.56MHz, specifying the physical interface, protocols and commands between the reader and the tag plus anti-collision methods. The anti-collision protocol can be divided into two modes, and mode 1 is divided into basic type and two extended protocols (no slot non-terminating multi-responder protocol and slot-terminated adaptive polling multi-responder reading protocol) . Mode 2 adopts the time-frequency multiplexing FTDMA protocol, with a total of 8 channels, which is suitable for situations with a large number of tags.

ISO/IEC 18000-4 Information Technology: Radio Frequency Identification for Item Management - Applicable to the microwave band 2.45GHz, specifies the physical interface, protocol and commands between the reader and the tag plus the anti-collision method. The standard includes two modes, mode 1 is the passive tag working mode is that the reader speaks first; mode 2 is the active tag, the working mode is the tag speaks first.

ISO/IEC 18000-6 Information Technology: Radio Frequency Identification for Single Product Management - Applicable to the UHF band 860-960MHz, specifying the physical interface, protocol and command between the reader and the tag plus the anti-collision method. It includes three interface protocols of TypeA, TypeB and TypeC passive tags, and the communication distance can reach up to 10m. Among them, Type C was drafted by EPCglobal and approved in July 2006. It has greatly improved in recognition speed, read and write speed, data capacity, anti-collision, information security, frequency band adaptability, anti-interference and other aspects. In 2006, the V4.0 draft was submitted, which expanded the characteristics of electronic tags with auxiliary power and sensors, including tag data storage methods and interactive commands. Active tags with batteries provide greater read range and communication reliability, but are larger and more expensive.

ISO/IEC 18000-7: Applicable to UHF band 433.92MHz, which belongs to active electronic tags. Specifies the physical interface, protocol, and commands between the reader and tag plus the anti-collision method. Active tags have a wide reading range and are suitable for tracking large fixed Assets.

The five frequency band air interface protocols formulated by ISO/IEC fully reflect the relativity of standard unification. One standard is a common requirement for a wide range of application systems, but not all application systems. A set of standards can meet a wider range of requirements. Application requirements.

In the application of UHF RFID, the air interface protocol is the basis for solving the interface standard problems of each layer. On the surface, the purpose of formulating, promulgating and implementing RFID standards is to solve problems such as coding, communication, air interface and data sharing, and to maximize the application of RFID technology and related systems in my country. In fact, the dispute over RFID standards is a dispute over the control of item information and the control of the RFID industry. It is related to national security, the implementation of technology strategies and the development of the RFID industry. It is essentially a conflict of interests.