May 08, 2006In late March, EPCglobal, the GS1 subsidiary and driver of standards for the use of RFID in the supply chain, hosted a technology demonstration event to determine which frequency bands would be best suited for using RFID to identify and track individual items, as opposed to cases and pallets. The event also helped decide whether the group needed new air-interface protocol standards to address its user requirements for item-level tagging (see EPCglobal Puts Item Tagging to the Test).
The tests resulted in a kind of showdown between high-frequency (HF) 13.56 MHz tags and ultrahigh-frequency (UHF) 915 MHz tags. The former has a shorter read range but tends to perform better on items that cause RF interference. Still, advances in tag design are showing that UHF tags can be resilient to RF interference at close range to the interrogator. Based on the results of these tests, EPCglobal has just announced it is forming an HF standards development working group to create a new standard for passive HF tags.
"What came out of the demonstration [tests] is that the options are better for both HF and UHF than anyone imagined they were," says Sue Hutchinson, director of industry adoption for EPCglobal US, located in Lawrenceville, N.J., and the facilitator of the demonstration tests. There are some applications, she says, where HF technology can address the needs of EPCglobal's member companies. Therefore, the group has decided to develop a standard for HF systems.
EPCglobal created a first-generation specification for an HF standard, but never ratified it. According to EPCglobal, the new HF working group will build on that specification and gather EPCglobal member requirements for an HF tag targeted for use in the health-care sector. Once a specification has been completed, it will be brought through the ratification process the organization uses for its air-interface protocols, starting with a working draft.
The International Standards Organization (ISO) has a number of HF standards already in place. GlaxoSmithKline and Pfizer are both running technology pilots in which HF tags, based on the ISO 15693 standard, are attached to individual drug bottles, with UHF tags used at the case and pallet level (see GlaxoSmithKline Tests RFID on HIV Drug and Pfizer Using RFID to Fight Fake Viagra).
Hutchinson, however, says EPCglobal will develop its own HF standard. "There have been tremendous advances around memory structure, security and simplifying the command set that we pioneered with the UHF Gen 2 effort," she says. "And we'd like to see which of those concepts could be incorporated in an HF air-interface protocol to make it more useable by our community. Many of the radio or signaling techniques currently being used in the [ISO 15693-compliant] tags and readers Pfizer and GlaxoSmithKline are using for their pilots will be explored for the EPCglobal HF protocol, as will others that have been used successfully for access control and other applications."
Though the HF Gen 1 specification was never ratified, the upcoming HF standard will be referred to as the HF Gen 2 standard. This, Hutchinson says, is because it will leverage much of the nomenclature for the existing UHF Gen 2 standard. Specifically, the HF Gen standard will share many of the digital (as opposed to analog) layers of the UHF Gen 2 protocol. These will include memory usage and allocation, data structure, and commands such as how to lock or erase data encoded to a tag, or how interrogators can filter tag data to pull only the data the end user needs. "We want to take advantage of the lessons we learned in the UHF Gen 2 protocol," she says.
EPCglobal also announced that it's creating a UHF air-interface working group to develop additions to the UHF Gen 2 standard, enabling users to bolster the security of the data encoded to UHF Gen 2 tags. The security measures are being designed specifically to address data encoded to tags placed at the item level, or directly onto the packaging of or embedded into consumer products. The purpose of these measures is to prevent the tags from being read or altered by unauthorized parties. This would be specifically useful for tags embedded in or attached to consumer goods that may remain with a product after purchase. A number of consumer and advocacy groups have been encouraging the development of improved tag data security in recent months, as credit cards and other items consumers use are now starting to include RFID tags. Researchers have also identified a number of ways the personal information encoded to passive RFID tags could be tampered with or surreptitiously read by nefarious parties such as identity thieves (see Attack on a Cryptographic RFID Device and EPC Tags Subject to Phone Attacks).
It is not EPCglobal's intention, however, to create subsets of the UHF or HF standards for specific uses, Hutchinson explains. Whatever security tools the UHF working group develops will be added to the UHF Gen 2 standard through an amendment process. Hutchinson says it is too early to say whether these additions will require any changes to the chip used in the tag, or if they could be deployed through a software or firmware upgrade to the Gen 2 interrogators used to read Gen 2 UHF tags. Any data security tools EPCglobal adds to the Gen 2 air-interface protocol will also be incorporated in the Gen 2 HF standard being developed.