Countless business applications, from product manufacturing to end-customer sales, can benefit from Radio Frequency Identification (RFID). With RFID, logistics become more effective, stock handling is easier, traceability is guaranteed, cloning and counterfeiting can be avoided, antitheft protection is enabled, and warranty problems can be easily eliminated.
 DEFINITIONS
What is Radio Frequency Identification (RFID)?
Radio frequency identification (RFID) technology uses radio communications to uniquely identify items, such as goods, people, or animals. It enables automated collection of information on identified items independently from their position, without the need of a direct optical link or human intervention. RFID also liberates the user from harsh or dirty environment concerns that restrict other automatic identification solutions such as barcode. On top of that, RFID is used as a bi-directional data carrier since it allows information attached to the item to be written and updated on the fly.
What does an RFID System consist of?
An RFID system consists of several components including one or multiple contactless memory tags (or transponders), attached to the items to be labeled, identified, and traced, and handheld or fixed contactless read/write reader station units or coupling devices exchanging data with the transponder(s) by means of RF signals.
Contactless memory tags (transponders) are the backbone of the RFID system since they contain the data that identify the items. A contactless memory tag is made of a non-volatile memory associated with a radio frequency communication block that performs RF signal modulation, demodulation, and power supply regulation, and an antenna. A transponder can be read-only (ROM), one-time-programmable (OTP), or read/write (EEPROM), and it can be embedded in various package formats (e.g. inlays, cards, and buttons).
The reader (or reader station unit) is connected to the antenna that transmits and receives the radio frequency signal from and to the transponder(s). The reader sends an RF signal to the transponder’s antenna. This signal generates a voltage that is rectified and provides a power source to the transponder. The power transfer from the reader to the transponder is performed through an inductive coupling between the two coils in 125 KHz and 13.56 MHz systems. For ultra-high frequencies (UHF), the electric field generated by the reader is used to power the tag. In other words, the transponder does not need a dedicated power supply.
There are two main families of transponders, passive (battery-less) and active. Adding a battery can bring several advantages, such as improvement of the reading range or continuous monitoring of temperature and pressure etc., but adds an extra cost. During the reader-transponder communication, the RF signal generated by the reader is modulated according to the data to be sent. In the transponder-reader direction, no modulation is applied on the reader RF signal and the communication is done through load modulation in inductive coupling systems. The reader interfaces with the RFID system control host through a serial interface such as RS232, RS422/485, or USB.
TECHNICAL PRINCIPLES
Anti-collision Mechanism
The anti-collision mechanism allows the reader to detect and identify all transponders in its operating range and individually access each one of them. Each transponder is uniquely identifiable by its dedicated Unique ID (UID). Transponders that are not equipped with the anti-collision mechanism can only be accessed one at a time. Transponders can only respond to incoming requests and the communication is based on the concept of “reader talks first”. The reader sends a request to all transponders in its operating field. This “inventory” message prompts the transponders to respond using the method presented above. In case there are multiple transponders around, they all understand the message coming from the reader and are obliged to respond. If they all answer at the same time, their replies will corrupt each other and the reader will not be able to decipher them. To cope with this issue, an anti-collision mechanism has been put in place. In ISO15693, for example, a slot-marker mechanism is enabled, based on a unique transponder identification number (UID) and an application family identifier (AFI). In cases when only a smaller number (up to 50) of transponders needs to be uniquely selected, simpler algorithms can be used, such as a system based on a chip identification number (Chip_ID) in ST’s short-range products. In UHF, the data-matching mechanism is based on the EPC (Electronic Product Code) numbering scheme in the EPC Class 1 Generation 1 (ST’s XRA00).
Unique Identifier or UID (also Tag ID or TID)
In ST’s contactless memory products, the UID is typically a 64-bit identifier that can be used by an anti-collision algorithm, such as the ISO15693 standard. The UID enables unique identification of a large number (from fifty to thousands) of transponders in the reader field. The UID is programmed in the transponder during the manufacturing process and can never be changed afterwards. In ISO15693, the reader sends out an inventory request and performs the transponder-identification sequence in a deterministic way. Each transponder sends back its UID to identify itself to the reader.
Chip Identifier or Chip_ID
The Chip_ID is typically an 8-bit handle used by the anti-collision algorithm in ST’s short-range family products. The Chip_ID enables unique identification of a small number of transponders in the reader field. This identifier is either programmed by the transponder issuer or generated by the transponder itself upon entering the reader field.
Application Family Identifier or AFI
In ISO15693, the AFI describes the type of application targeted by the reader. This identifier is used to extract all transponders in the reader field that meet the required application criteria. After the reader sends out the AFI, only the AFI-compliant transponders of the appropriate family will respond.
Programmed by the transponder issuer, the AFI is read-only and its value cannot be modified.
EPC code
The EPC code is a Unique Item ID (UII) defined in the EPCglobal specification. It is a 64- or 96-bit code, programmed by the end customer. The EPC ID consists of a group of 3 unique codes, specifying the item’s maker, class, and its serial number. Like for the bar code, EPC codes are administered and distributed to its members by EPCglobal, an organization promoting an open global standard for real-time, automatic identification of items in the supply chain management.
Anti-clone Function (ACF)
The ST anti-clone function (ACF) protects an application from counterfeiting by enabling the RFID system to authenticate the transponders. ST’s ACF has been successfully embedded and proven reliable in a wide range of RFID systems, including pre-payment, anti-counterfeiting, and brand-protection applications.
OPERATING RANGES AND APPLICATIONS
Close Coupling, Short Range, Long Range, and Extended Range Applications
The RFID operating ranges are defined by the distance between the transponder(s) and the reader.
The close-coupling range includes the transponder-reader distances up to 5 cm. Brand protection, anti-counterfeiting of electronic goods and food consumables, as well as electronic purchases at vending machines operate in the close-coupling range. These applications employ low-cost readers operating with a limited number of transponders and require security features such as password, anti-clone, or cryptographic capabilities.
In addition, RF technology systems are a universal solution for various ticketing applications, no matter what means of transport (public transportation or private car) are used. Contactless systems can be also used in a wide range of access-control applications, including entrance systems to and within public buildings (offices), time and attendance systems, room logistics at hotels, locking systems, and amusement parks. These short-range or proximity-range applications use low-cost transponders embedded in plastic cards or paper tickets and they operate in the range up to 20 cm. Readers and transponders from different suppliers must be fully interoperable. Required security levels are satisfied through password, anti-clone, or cryptographic capabilities.
RF transponders are a low-cost universal solution for tracking a wide variety of valuable assets (e.g. package delivery, animal tracking) and improving the product supply chain management from manufacturing to stock handling to distribution. Capable of storing traceability history, transponders provide accurate real-time information on each tagged item. Similarly, they can be used for anti-theft application (using Electric Article Surveillance) or access control from a longer distance.
These long-range or vicinity-range applications operate within one meter from the reader and typically involve a large number of low-cost transponders (100+), requiring reliable anti-collision mechanisms and transponder-reader interoperability.
Extended or very long-range (up to 10 meters) RFID systems will be instrumental in creating low-cost contactless solutions for new supply chain, logistics, and tracking applications that can offer improved efficiency, accuracy, and security standards to major manufacturers, retailers, and their customers.
MARKET AND TRENDS
 RFID is an emerging technology with a high growth potential. Its overall CAGR (compound annual gross rate) between 2006 and 2010 has been estimated at 35%, with the RFID global revenues exceeding $3 billion by the end of 2007. (source: Venture Development Corporation (VDC)
Faster market adoption is currently limited by the high cost per unit and the slow adoption of the UHF Gen2 standard, defined by EPCglobal and adopted as ISO 18000-6c in 2006.The market’s demand for reduced costs and new technical features have led ST to develop a completely new design of transponders, equipped with advanced capabilities like anti-collision, write capability, and adaptive packaging, according to the requirements of the final application.
The RFID market is populated by various players, including silicon manufacturers, inlet makers, suppliers of converters, readers, and antennas, and software and integration service providers.
ST’s strategy is to become one of the main semiconductor players in the transponder segment by pushing devices compliant with standards like ISO and EPCglobal and introducing value-added innovative products in addition to commoditized large-volume devices.
ISO STANDARDS
The ISO organization defines and promotes worldwide-recognized standards in the contactless area. Three standards for objects operating in the 13.56MHz frequency range have already been approved:
- ISO10536 identification cards and contactless integrated circuits cards – Close-coupling cards (reading range below 2 cm).
- ISO 14443 identification cards and contactless integrated circuits cards – Proximity cards (reading range up to 20 cm).
- ISO 15693 identification cards and contactless integrated circuits cards – Vicinity cards (reading range up to 1 m). This standard is part of the future SC31/ISO18000 standard, currently under discussion.
ISO standards are recognized worldwide and guarantee the full interoperability of transponders and readers from different suppliers. ST’s contactless memories are ISO-compatible: ISO 14443 type B for short-range devices, ISO 15693 or ISO18000-3 Mode 1 for long-range devices, and ISO 18000-6c for UHF passive devices.
EPCglobal SPECIFICATIONS
STMicroelectronics is a member of the EPCglobal (formerly AutoID Center), an industry consortium dedicated to creating and implementing next-generation automatic identification solutions, primarily RFID. The Center has created two specifications, the EPC Class I-b UHF and a more recent EPC Class I Generation 2, which are focused on improvements in supply chain management and barcode replacement.
ST’s OFFERING IN RFID and RF memory products
As far as technology is concerned, ST has decided to support actively 13.56MHz and UHF-based contactless systems.
Long-range RFID ICs
ST’s LRI64 offers 64 bits of user OTP block memory. The memory is organized as 15 blocks of 8 bits. The first eight blocks store a 64-bit read-only unique identifier used during inventory sequence, followed by the AFI (Application Family Identifier code) and the DSFID blocks. The last five blocks are user-programmable. The device has an internal tuning capacitor. The LRI64 contactless memory allows RFID to enter new areas of electronic bar-code applications with a unique combination of features and unprecedented cost-effectiveness. The LRI64 complies with the recommendations of the ISO 15693 and the ISO 18000-3 Mode 1 standards.
The LRI2K, a 2K-bit write-lockable EEPROM, features a 64-bit read-only UID, an 8-bit DSFID (Data Storage Format IDentifier), and an 8-bit AFI code, uniquely identifying the device for performing ISO-compliant anti-collision mechanisms. The product is equipped with an additional Electric Article Surveillance (EAS) feature, which provides anti-theft capability for point-of-sale applications such as shops and libraries. The memory array is organized in 64 blocks of 32 bits. Each memory block can be individually write-protected in order to prevent any subsequent modification of the data. The product will be fully compliant with the ISO 15693 and the ISO 18000-3 mode 1 standards for RFID.
En enhanced version of ST’s LRI2K, the LRIS2K provides, security features such as password protection defining an access profile to memory words. Thanks to its flexible security scheme and three passwords, the LRIS2K can advantageously be used along the supply chain to safely trace the product’s history.
Short-range Contactless Memories: SRIX4K, SRI4K, SRI512
ST’s SRIX4K includes 4096 bits of non-volatile memory organized in three areas: the first area is an OTP (One Time Programmable) bit zone, in which bits can only be switched from 1 to 0; the second area provides two 32-bit binary down counters; and the last area, which is a non-volatile memory split into 32-bit blocks (9 blocks are lockable). The SRIX4K supports France Telecom’s proprietary anti-clone function and anti-collision mechanism based on an 8-bit Chip_ID.
The SRI4K offers the same features as the SRIX4K without the authentication functionality.
ST has recently expanded its ISO14443-B short-range contactless memory portfolio by introducing the SRI512 with 512 bits of non-volatile memory and anti-collision capability. Its derivative product with a different memory configuration, the SRT512, supports mass transit ticketing specifications such as “Intertic”, issued by the French Normalization Association (AFNOR).
All three devices (SRIX4K, SRI4K, SRI512) are designed for short-range applications such as consumable products identification, anti-counterfeiting, or ticketing solutions.
Short-range: CR14 and CRX14 RF Coupler
The CRX14 is a short-range contactless chip coupler compliant with the ISO14443 type B standard. It interfaces with the host CPU that manages the communications protocol in both directions through the industry-standard I²C serial bus. The coupler is equipped with France Telecom’s proprietary anti-clone function and anti-collision mechanism. The CRX14 is supplied in SO16N packages.
A complete solution combining the CRX14 coupler and SRxx transponders operates in the short range and ensures a total compatibility in terms of memory tag protocol access. In addition, the combination of the CRX14 and SRI512 or SRIX4K memories guarantees a high level of system security for short-range and low-cost applications. Optimized for interoperability, these products can also work independently, with any ISO-standard chips.
The CR14 is based on the CRX14, excluding the support of France Telecom’s proprietary anti-clone function.
UHF Products: XRAG2
The XRAG2 features 432 bits of EEPROM, where 128 or 256 bits are dedicated to the EPC code, 16 bits to CRC, and 64 bits to TagID. The device, based on the EPC Class1 Gen2 specification V1.0.9, supports kill, lock, and anti-collision functionality. The key differentiator of the XRAG2 compared to competing silicon solutions is 128 bits of user memory.
ST Technology for RFID and RF memory products
ST RFID Products and couplers are manufactured using a highly reliable and mature CMOS technology with embedded EEPROM, well-suited to address high-volume, cost-driven markets. Allowing at least 1 million program-erase/write cycles and a minimum data retention of 40 years, ST’s mature and reliable EEPROM technology enables production of the CRX14 couplers and transponders in very large volumes (hundreds of millions).
ST Transponder Packaging
There is no given form factor for RFID devices. Various antennas or inlays are offered using different materials such as copper wire, etched copper, or printed conductive ink. Transponders can also be delivered in unsawn wafers or sawn and bumped wafers. Final packaging depends on application requirements, such as temperature, pressure, or chemical environment, and various “over-packaging” (or converting) steps are offered by specialized companies, too.
ST STRATEGY FOR RFID and RF memory products
STMicroelectronics is a worldwide leader in EEPROM products, including standard memories up to 1-Mbit density, and ASMs (Application Specific Memories). The Company has also participated in defining the standards for contactless memory communications, including ISO14443 type B, ISO15693, ISO18000, and EPCglobal.
ST offers ISO-standard and custom RFID products and helps its key customers access and exploit the contactless application world. The Company’s current portfolio of contactless memories will be expanded to match different target applications, in accordance with open standards.
Committed to high-volume/low-cost identification solutions, ST offers low-cost, standard-compliant RFID chips and complete systems through its wide partner network (reader and converter makers, inlets makers). The Company has built strong relationships with key players in this field and developed a wide variety of RFID products for applications in retail, mass transit, vending machines and many others.
CONCLUSION
Contactless tags are a universal cost-effective identification solution addressing a wide range of applications. Anti-collision capability and its ability to be read or written without a direct line of sight make this technology more efficient in comparison with currently used systems, such as paper barcodes or dot matrices. Since no item can pass by a transponder reader without being scanned and/or updated, human intervention and its associated costs are significantly reduced.
Its experience in the contactless domain, partnerships with system integrators, and strong involvement in standardization activities have enabled STMicroelectronics to develop a highly cost-efficient, flexible, and interoperable portfolio of contactless identification products.
For more information on ST’s offering in RFID visit www.st.com/rfid
April 2008
GLOSSARY
RF
Radio Frequency
RFID
Radio Frequency Identification
CONTACTLESS MEMORY or TRANSPONDER
A memory assembled to an antenna
SMART CARD
An MCU-based plastic card that interfaces to network terminal devices
RFID LABEL
A transponder in the form of an adhesive paper label
EAS
Electric Article Surveillance
UID
Unique Identifier. In ST products, it is a 64-bit unique number, programmed on internal production lines, used to uniquely identify the transponder during an anti-collision sequence.
Chip_ID
Chip Identification Number. In the short-range device family, the Chip_ID is a 8-bit handle value used to differentiate and select multiple transponders.
AFI
Application Family Identifier. AFI, defined in the ISO15693, represents the type of application targeted by the reader. It is used to extract all transponders in the reader field that meet the required application criteria. AFI is coded on one byte, which constitutes two 4-bit groups (nibbles). The most significant nibble of AFI is used to code one specific or all application families. The least significant nibble of AFI is used to code one specific or all application sub-families.
DSFID
Data Storage Format Identifier. The DSFID, defined in the ISO15693, indicates how the data is structured in the transponder memory. It is coded on one byte and provides instant information about the logical organization of the data.
EPC
Electronic Product Code is the unique object identifier (license plate) stored in the tag. The EPC code contains a Header, an EPC Manager Number that identifies the item maker, an Object Class number that classifies] the item, and a Serial Number that uniquely identifies the item. The EPC code is provided by the EPCglobal organization.
INTEROPERABILITY
Interoperability is the capability of readers to “understand” all contactless memory transponders in its communication field, regardless of their supplier. The best (and perhaps only) way to achieve interoperability is to adopt a standard. Numerous solutions exist today, but they often use proprietary protocol and/or not yet approved frequency band. Compliance with a contactless standard is synonym of worldwide interoperability.
CRC
Cyclic Redundancy Check (error detection scheme).
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