SECTION V: Understanding Radio Frequency IDentification (RFID)

ISO (LF, HF and UHF)

Low frequency is the oldest adopted RFID technology, which has been implemented mostly in manufacturing and agricultural applications. Thus far, there has been little work done in terms of standardization in the low frequency arena. This is mainly due to the fact that most of these implementations have been in closed-loop and controlled environments. In the agriculture sector, however, the nature of animal tracking has required some standardization. ISO 18000-2, 11784 and 11785 are the notable standards in the low frequency technology that has been in use for some time in animal tracking.

ISO 11784 and 11785 are specifically designed for animal tracking and work in tandem. In brief, ISO 11784 defines the data structure of the animal tag. In this standard, animals can be identified by country code and unique national ID. There are also provisions to use a manufacturer code in place of the country code. ISO 11785 is concerned with the technical aspects of reader-tag communication. There are several shortcomings in these two standards that have limited its widespread usage but they have proven effective where implemented.

ISO has renewed its efforts to develop standards for the low frequency. The process is managed by the SC31 / WG 4 which has been mandated with the responsibility to create standards for “Radio Frequency Identification for Item Management”. The 18000 series encompass all different frequencies. ISO 18000-2 was finalized and published in 2004. This is the standard defining parameters for air interface communications below 135KHz, that is, the LF range. We should take note that the EPC Global is also working towards creating standards and specifications for the LF RFID.

Amongst all the different RFID technologies, high frequency has the most established and commonly used standards. This could be attributed to the fact that 13.56 MHz is a globally available frequency for RFID, JTC1/SC17/WG8, which is the work group for “Contact-less Integrated Circuit Cards”, and started the standardization process for HF RFID in 1995. That resulted in ISO 15693 and 14443, the most widely RFID standards used to date.

ISO 15693 was published in 2000 defining parameters for vicinity RFID cards, generally used in applications that require read ranges of more than 10 cm. The specifications have been organized in three separate parts covering physical characteristic, air interface and communication protocol.

ISO 14443 is the standard for the proximity RFID cards with the read range being limited to less than 10 cm. This standard is organized much the same way as the 15693 standard defining similar parameters in different parts of the standard. The main difference between these two standards is their intended application. ISO14443, because of its short read distance and encryption capabilities, is more suitable for applications where security is a serious concern such as electronic payment, banking and financial transactions. In addition to the two standards discussed, SC17/WG8 has drafted several other standards pertaining to the use of RFID which is outside of the scope of our discussions here.

Although ISO 15693 and 14443 are the established standards and have worked well so far, some industry experts are of the opinion that they do not address all the issues. ISO started a more focused process under the SC31 umbrella for RFID standardization. ISO 18000-3 is the new standard for 13.56 MHz RFID. This standard was published in 2004 after 3 years of deliberation. ISO 18000-3 is a comprehensive standard that has built upon the existing ISO 15693. It has two versions, with version 1 being very similar to ISO 15693.

Moving on to the UHF (860 MHz-956MHz) band, we see the highest concentration of energy and efforts to draw standards. At present, there is no globally accepted frequency within the UHF band, due to restriction in different regions of the world. Realizing that RFID will not have access to a uniform worldwide frequency in the UHF band, the industry has come to terms with this fact and have started developing products that are either specific to the region or able to work with different frequencies. In North America, UHF RFID uses 902MHz-928MHz where 860MHz-868MHz and 950MHz-956MHz are used in Europe and Japan respectively.

ISO’s work in the 860 – 956MHz UHF band has resulted in ISO 18000-6, which has been published. This standard defines parameters for air interface and communications.  As in the case of other 18000 series standards, part 6 covers all technical aspects of RFID communications in great detail.

As mentioned above, 18000 series defines the air interface parameters for different frequencies in parts 2-7 and part 1 covers general parameters common to them. In addition, ISO/IEC 15961, 15962 and 15963 have been finalized and published in the fall 2004. ISO/IEC 15691 defines parameters and commands for communication with the application software while ISO/IEC 15962 deals with the processing of data and its presentation to the RF tag, and the initial processing of data captured from the RF tag. ISO/IEC 15963 deals with the unique identification code (UID) and describes the numbering scheme for tags.

Table 1 below is a summary of the most common ISO standards.

Table 1 – Common ISO Passive RFID Standards

Thus far, we have mainly focused on the ISO standards. At this point, we are going to turn our attention to EPC Global initiatives.

EPC (HF and UHF)

EPC Global’s mission started with the vision to identify every item with a unique electronic product code (EPC). A global network will be implemented to make every item visible throughout the supply chain. A great amount of research and development resources have been invested in creating specification and standardization of the EPC tags and the required infrastructure. Although EPC Global efforts are not limited to the UHF, it has been their main focus.

EPC Global through its research wing, Auto ID Labs, has defined specifications for different classes of EPC tags. Currently, class 0 and class 1 tags are commercially available. Class 0 EPC tags have a factory programmed 96 bit code whereas class 1 facilitates user programmable codes. EPC Global has proposed other classes of EPC tags that would provide user memory beyond the ID code. It has also created detailed specifications for the structure of the 96-bit code flexible enough to incorporate other coding standards currently in use in the supply chain. The 96-bit EPC provides unique identifiers for 268 million companies. Each manufacturer can have 16 million object classes and 68 billion serial numbers in each class. There are new numbering schemes have been introduced with 128-bit and 256-bit serial numbers to accommodate exiting identification standards. The latest EPC standard, Class 1 Gen 2 has been ratified.

EPC network or UCCNET as dubbed recently, will track EPC tagged objects as they move through the supply chain from source to consumption. We will briefly describe different components of the EPC network below:

EPC Network Description:

• ONS (Object Naming Services) is analogous to DNS (Domain Name System) in a typical network. Every EPC tag is tied to the detailed item information through a local network or the Web
• Savant is the software technology to serve as the nerve system for the network managing flow of data
• Physical Markup Language (PML) is a sub set of XML language that has been specified as the standard development platform for the EPC network

The RFID industry is moving fast to enhance current standards and create the new ones required for the worldwide implementation of the technology. We are witnessing considerable efforts channeled towards this goal and we hope that standardization process can soon catch up with advancements in other aspects of the industry. ISO is the global authority for standardization and EPC Global is a major force in the RFID market with the great support of the consumer industry. Although it is possible for these two organizations to work side by side, some believe that there could be more achieved through collaboration than competition when it comes to standardization.

Table 2 below is a summary of EPC Global specifications

Table 2 – EPC Global Specifications

• The data format, memory partitioning and essential functions (inventory, read, write, lock and kill) are identical for both standards. This implies that EPC based applications can treat UHF tags and HF tags identically.The UHF and HF specifications are logically similar. Consequently, the Low-Level Reader Protocol (LLRP) supports EPC Global UHF Gen2 V1.2.0 and EPC Global HF Gen2 V1.0.3.

• The signaling layer used by EPC Global UHF Gen2 V1.2.0 and EPC Global HF Gen2 V1.0.3 are diverse ways of communicating with HF tags and UHF tags.
• Both the UHF and HF Standards implement the item level requirements identically

Continue reading…click here for Section VI: RFID SYSTEM IMPLEMENTATION