HF Protocols' Distant Dream

By John Schroeter

Feb. 12, 2007—While the many high-frequency (HF) RFID air-interface protocols enjoy global operation at a single frequency (13.56 MHz), the problem is that none of them are compatible, let alone interoperable. These protocols include ISO 14443A, ISO 14443B, ISO 15693, ISO 18000-3 Mode 2 and EPCglobal HF Class 1. And, as one might expect, each has its own data structures, requires infrastructures that are incompatible, and often operates on readers with nonstandard features and functionality. This results in a proprietary platform rather than a standards-based model.

Unfortunately, addressing these problems with multiprotocol HF readers only creates more problems: higher reader complexity and cost, lower read rates and less overall read reliability (read opportunities are always compromised when an interrogator must cycle through multiple protocols). In short, trying to navigate an HF landscape beleaguered by so many incompatible standards is an exercise in futility.


And it gets worse. Even within the same HF protocol (pick one!), each of the various tag chips on the market has a different memory map. This means the data field required by any one standard is stored in different memory locations, placing additional burdens on the readers. And we haven't even begun to address the different timing requirements of each HF protocol!

Any one of these issues would preclude interoperability. Clearly, then, HF has a long way to go before it can play on the world stage. And the clarion call from that stage is for a single, worldwide infrastructure able to address all use cases from pallets to items. UHF Gen 2 answered this call—resoundingly so. It is, in fact, RFID's only worldwide standard. With UHF Gen 2, reader and tag manufacturers have introduced products that operate at all regional UHF frequencies using the same communications protocol.

In a global supply chain, users can choose Gen 2 tags that any Gen 2 reader operating within the locally regulated frequency band, in any part of the world, can program and read. Even employing a common frequency, however, HF cannot begin to approach this capability. And while there is some movement to produce an "HF Gen 2" standard with a view to solving the interoperability problem, certified product availability would be two or more years away—assuming anyone would actually build it at that point.

In addition to hindering the ability to realize a globally interoperable network, HF's multiple standards also translate into major costs. Enterprises opting for HF for item-level tagging must still implement UHF Gen 2 for case- and pallet-level applications; HF cannot perform in the far field. As such, multiple infrastructures—involving UHF Gen 2 and possibly multiple HF standards—will be required to meet tagging needs.

When users are forced to deploy two, three or more RFID infrastructures, the complexity and cost of RFID technology become prohibitive, to say nothing of the logistics nightmare such scenarios present. Such a predicament, however, is completely unnecessary. UHF Gen 2 covers all supply chain applications, from pallets to cases to individual items—near and far, worldwide. What's more, interoperability means it will always be the most cost-effective RFID solution available—period.

John Schroeter is senior marketing communications manager at Impinj, a Seattle-based provider of EPC Gen 2 UHF RFID chips and technology. Prior to joining Impinj, Schroeter held marketing management posts at UTMC, Seattle Silicon and Fairchild Semiconductor's memory and high-speed logic division. He is the author of the Prentice Hall book Surviving the ASIC Experience.