Development of key RFID tag technology applications and current international research status

　　RFID is a general term for radio frequency identification technology. Like barcodes, IC cards, and other identification methods, its basic function is to identify the unique identifier (UID) of the target item. The difference is that it uses radio frequency transmission to achieve contactless automatic identification, enabling the identification of moving targets and multiple targets. RFID is also a data communication technology, possessing the basic components of communication systems such as sending, receiving, channeling, and transmitting information. The difference is that the information transmitted is artificial and standardized. With its large storage capacity, multiple target recognition, long reading distance, and data encryption, as well as its development potential, RFID is regarded as one of today's important technologies. The key to RFID system application and development lies in electronic tags. This paper focuses on the key technologies of electronic tags and the current research status at home and abroad, and proposes the basic countermeasures for the application and development of electronic tags in China at this stage.

　　1 Electronic Tag Technology and Current Research Status at Home and Abroad

　　In domestic and international research literature, current research on electronic tags mainly focuses on the following six aspects.

　　1.1 Chip Technology

　　Chip technology is a core technology within RFID technology. A tag chip is a system that integrates all circuits except the tag antenna and matching lines, including modules such as RF front-end, analog front-end, digital baseband, and memory units. The basic requirements for chips are lightweight, thin, small, low-cost, and low-cost.

　　Abroad, integrated circuit manufacturers such as TI, Intel, Philips, STMicroelectronics, Infineon, NXP, and Atmel have achieved outstanding results in developing small-size, low-power, and low-cost RFID chips. For example, Atmel's UHF passive tags can have a minimum RF input power as low as 16.7 μW. The Swiss Federal Institute of Technology has designed a 2.45 GB tag chip with a minimum input power of only 2.7μW and a read/write distance of up to 12 m. At the 2006 ISSCC conference, Japan's Hitachi Corporation proposed a label chip with an area of 0.15 mm × 0.15 mm and a thickness of only 7.5 μm. Domestically, Chinese integrated circuit manufacturers have been able to independently develop and produce low-frequency and high-frequency chips, approaching international advanced levels. The UHF band QR series chips developed by Shanghai Kunrui have already passed EPCglobal's official authorization and certification. Overall, the design of RFID chips in China's UHF and microwave frequency bands still faces significant challenges, mainly reflected in stringent power consumption limitations. Antenna compatibility technology. Subsequent packaging issues. Sensitivity issues. Reliability and cost.

　　The development trend of RFID chip design and manufacturing technology is lower power consumption, longer range, faster read/write speeds, higher reliability, and continuously decreasing costs. In addition to increasing tag storage capacity to carry more information, reducing tag size to lower costs, and improving tag sensitivity to extend reading distance, current research hotspots also include: ultra-low power circuits; Security and privacy technology, password functions and implementation; Low-cost chip design and manufacturing technology; New storage technologies; Anti-collision algorithms and implementation technologies; Integration technology with sensors; A comprehensive solution closely integrated with application systems.

　　1.2 Antenna Design Technology

　　Miniaturization has always been a major concern in the design of RFID tag antennas. To expand the range of applications, miniaturized antenna bandwidth, gain characteristics, and cross-polarization characteristics are also important research directions. Currently, RFID tags still use off-chip independent antennas, which have the advantages of high Q-value, ease of manufacturing, and moderate cost, but they are larger in size and prone to breaking, making them unsuitable for anti-counterfeiting or implanting biological tags into animals. If the antenna can be integrated into the tag chip, it can operate without any external components, reducing the overall size of the tag and simplifying the label manufacturing process to lower costs. This has sparked research into on-chip antenna technology. In addition, current research focuses on tag antennas include antenna matching technology, structural optimization technology, broadband antenna design covering multiple frequency bands, multi-tag antenna optimization distribution technology, metal-resistant design technology, and consistency and anti-interference technology.

　　1.3 Packaging Technology

　　The packaging of electronic tags mainly includes key steps such as chip assembly and antenna fabrication. With the development of new packaging technologies, new processing techniques have emerged in label packaging technology, such as flip-chip bump generation (Bunping) and antenna printing. Compared with traditional wire-connected or carrier-to-carrier connections, flip-chip technology offers higher packaging density, good electrical and thermal performance, good reliability, and lower cost. Using conductive ink printed label antennas instead of traditional etching methods to manufacture label antennas has significantly reduced the cost of electronic label production. In addition, research hotspots in label packaging technology include low-temperature hot-pressing packaging processes, precision mechanism design optimization, multi-physical quantity detection and control, high-precision high-speed motion control, and online inspection technologies.

　　1.4 Label Application Technology

　　Based on the unique characteristics of RFID tags for object identification, there has been a surge in research on various functional tags. In addition to traditional item identification, tracking, and monitoring, research hotspots also include interactive smart tags, spatial positioning and tracking, ubiquitous computing, mobile payments, and anti-counterfeiting of items.

　　(1) Interactive smart tags. The structure of interactive smart tags still consists of a single-chip wireless micro-power transceiver and a microcontroller. Various required applications are prewritten into the microcontroller, and when necessary, these programs are called via wireless commands, enabling tags to perform various tasks required by IoT applications such as recognition, positioning, and data collection. The tag does not transmit any signals outward, but periodically receives and records signals sent by the coordinator via broadcast on the monitoring channel as needed. Only after receiving a wake-up command does it jump to the reader's work channel, receives instructions from the coordinator, and enters a state of information exchange with the reader according to pre-written programs, completing the specified task within the specified time before returning to monitoring and sleep mode. It is evident that the core of this technology is to quickly filter out invalid signals, achieving ultra-low power wireless long-distance transmission of tags, at the cost of requiring an additional coordinator. Because interactive smart tags solve key issues in IoT applications such as low cost, low power consumption, and wireless long-distance transmission, they expand the scope of electronic tag applications and can be widely applied in urban intelligent transportation systems, basic urban data collection systems, and other fields requiring long-distance identification, positioning, or data collection.

　　(2) Real-time positioning and tracking tags. Existing positioning systems mainly include satellite positioning systems, infrared or ultrasonic positioning systems, and mobile network-based positioning systems. However, due to limitations in positioning time, accuracy, and environmental conditions, there is currently no positioning technology that can fully solve the location information problems of facilities and items in complex indoor environments such as airport lobbies, exhibition halls, warehouses, supermarkets, libraries, underground parking lots, and underground mines. RFID technology offers a new solution for spatial positioning and tracking services, especially suitable for indoor positioning that satellite positioning systems struggle to handle. It mainly utilizes the unique identification characteristics of tags on objects, measuring the spatial position of items based on the signal strength of radio frequency communication between the reader and the tag installed on the object.

　　(3) Universal calculation labels. By combining with sensor technology, RFID tags can also sense the status information of objects or environments at IoT nodes, such as temperature, humidity, and lighting, and use wireless communication technology to transmit this information and its changes to computing units, improving environmental visibility to computing modules and building future ubiquitous computing infrastructure.

　　(4) Mobile payment tags. RFID mobile payment uses short-range communication between mobile terminals and POS terminals, allowing payment of transaction amounts via mobile phone charges or SIM card binding to bank accounts for bank transactions. RFID mobile payment is a product of the integration of the RFID industry and the telecommunications industry. Currently, there are mainly four application methods: Felica, NFC, DISIM, and RF-SIM. Among them, RF-SIM is a medium-short-range wireless communication technology based on SIM cards. It embeds an RF module inside the SIM card, which is used for normal mobile communication and authentication, establishing a physical connection with the phone. RF-SIM cards support all mobile phones on the market and serve as a comprehensive service platform that can replace wallets, keys, and ID cards.

　　(5) Anti-counterfeit labels. Traditional anti-counterfeiting technologies such as physical anti-counterfeiting, biological anti-counterfeiting, structural anti-counterfeiting, barcode and digital anti-counterfeiting lack uniqueness and exclusivity, are easily replicated, and cannot provide true anti-counterfeiting effects. RFID technology offers absolute advantages in anti-counterfeiting, as each tag has a globally unique ID number that cannot be altered or forged. In addition, RFID anti-counterfeiting technology features no physical wear, high security of the reader's physical interface, encryptable tag data, and mutual authentication between the reader and tag, so it is basically impossible to fully replicate and thus effectively prevents counterfeiting. Currently, RFID anti-counterfeiting has gradually been applied in document management, ticket management, electronic license plates, alcohol anti-counterfeiting, and art treasure anti-counterfeiting, showing an expanding trend.

　　1.5 Research on standard issues

　　Currently, the main international communication standards related to electronic tags are: (1) ISO/TEC18000 standards. (2) EPC standards, (3) DSRC standards. (4) UID standard. In addition, many countries and institutions are actively formulating RFID-related regional, domestic, or industry alliance standards, hoping to upgrade them to interdisciplinary standards through various channels. Each standard system is divided into multiple parts based on operating frequency, and they are incompatible mainly in communication methods, collision prevention protocols, and data formats. In January 2008, the EU FP7 project team sponsored the Global Universal RFID Standards Forum (GRIFS), aiming to achieve maximum global consistency in RFID standards through enhanced collaboration. With the development of RFID technology, various standards for electronic tags are merging. For example, the ISO/IFC15693 standard for high-frequency 13.56 MHz has become part of the ISO18000-3 standard, and the EPC GEN2 standard has become the ISO18000-6C standard. Currently, the United States, the European Union, and other countries each adopt their own different standards. Due to the difficulty of coordinating interests, although the unification of standards is urgent, the process remains relatively lengthy.

　　1.6 Research on Security and Privacy Issues

　　The security mechanisms studied and adopted mainly include physical methods, cryptographic mechanisms, and their combinations. Physical methods are commonly used in low-cost labels, protecting tag information through electrostatic shielding or active interference. Compared to hardware security mechanisms based on physical methods, software security mechanisms based on cryptographic technology are more favored, mainly utilizing various mature cryptographic schemes and mechanisms to design cryptographic protocols that meet RFID security requirements.

　　2 Development Trends and Countermeasures for Electronic Tags

　　The application and development of electronic tags are built on the foundation of the RFID industry chain; any lag in any link will affect the overall industry growth. Our research and development time in the RFID field lags behind Europe, the US, South Korea, and Japan, and we still lack a complete industry chain in UHF and microwave frequency bands. To develop Chinese electronic tags based on existing domestic RFID technology and market base, we must target the entire RFID industry chain and formulate specific measures and strategies.

　　(1) Increase R&D efforts and seek technological breakthroughs. Currently, electronic tags still have many defects, such as low reliability in single tag reading due to antenna directionality, which easily leads to missed readings; RFID signals are easily affected by conductive substances like metal and water, leading to reduced recognition distance; when RFID systems operate simultaneously with other wireless communication systems with similar frequency bands, electromagnetic interference may affect their performance; and when many RFID tags are placed together, the tag antenna may exhibit array effects that differ from individual tag antennas. All of these pose challenges to the development of electronic tags.

　　(2) Establish relevant standards for electronic labels as soon as possible.

　　(3) Identify breakthrough points in applications and expand the scale of industry applications. Enterprises often remain at the surface level, with simple business processes, single logic, and lack integration of backend systems, so electronic tags have not truly played their role in supply chain management and enterprise informatization. Therefore, how to integrate RFID with existing enterprise information systems such as ERP, SCM, MIS, etc., innovate business processes, fully leverage the advantages of electronic tags, expand industry application scale, and form a complete industrial chain is an urgent issue to be solved in the near future.

　　(4) Strengthen technology integration to achieve cross-regional and cross-industry applications. With the continuous expansion of RFID development, it has recently found new applications in Expo ticket management, intelligent transportation, logistics, food safety, anti-counterfeiting of goods, electricity, and other fields. China's RFID industry has shifted from government demand to market demand. In the process of RFID development, it is important to recognize both the potential of the RFID industry and the problems that arise during this process, using more scientific methods to continuously deepen RFID applications and thereby promote the development of the RFID industry within the region.

　　3. Conclusion

　　The article describes the basic functions, advantages, and development trends of RFID. It also introduces key technologies of electronic tags, as well as analyzes and studies the standards issues and security privacy issues that have arisen both domestically and internationally. Finally, it proposes basic policies and development trends for the current application and development of electronic tags in China. This has played a crucial role in the development of RFID.