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Japan's Upcoming Shift to 920 MHz Promises Better UHF Tags

The nation's revised UHF RFID regulations will narrow the global UHF frequency range, enabling tag makers to offer passive EPC RFID inlays with improved sensitivity.
By Claire Swedberg
Nov 15, 2011Japan is ushering in a change to its ultrahigh-frequency (UHF) band for radio frequency identification, resulting in spectrum that closely matches that of North America and thereby narrows the overall frequency range used worldwide for UHF EPC Gen 2 passive tags and readers. The nation's current 955 MHz band (952.2 to 957.4 MHz) will shift to a 920 MHz band (916.8 to 923.4 MHz), which is located in the middle of the 915 MHz band (902 to 928 MHz) used in United States. The new regulations, agreed upon in April of this year, are slated to go into effect on July 25, 2012.

The European Telecommunications Standards Institute (ETSI) EN 302 208 standard, employed in European countries, specifies the 866 MHz band (865.6 to 867.6 MHz) for passive UHF RFID tags, as do many Asian and Middle Eastern nations. In the United States, the Federal communications Commission (FCC) authorizes the 902 to 928 MHz UHF band for RFID, as do most other North and South American countries. Japan, on the other hand, has been utilizing 952.2 to 957.4 MHz, divided into various 200 kHz channels with a stringent spectrum mask (the amount that an RF signal can bleed outside of its assigned channel).

Chris Diorio, Impinj's chairman and CTO
Consequently, to accommodate the variations in worldwide regulations, RFID hardware manufacturers have needed to offer either three separate RFID tag models, each designed specifically for one of the three different bands (866, 915 or 955 MHz), or a tag designed to operate across all three bands—that is, 865.6 to 957.4, a frequency range of nearly 100 MHz.

For those producing the tags, as well as consumers using them, a 100 MHz frequency range is "is non-ideal, because designing a single tag to operate over a 100 MHz frequency range is very difficult," says Chris Diorio, the chairman and CTO of Impinj, which manufactures EPC Gen 2 UHF chips used worldwide. A tag that can operate over such a broad frequency band, he explains, is less sensitive than one designed to operate in only one of the three RFID UHF bands would be.

"In most cases," Diorio states, "a tag antenna designer must sacrifice tag sensitivity to achieve this 100 MHz frequency range." What's more, he adds, because there can be a slight frequency range shift when a tag is placed on an object, tag antenna designers must design for an even wider range than 100 MHz. "All of us in the hardware community have hoped that a day will come when Europe, North America and Japan can all use the same frequency band. That day is one step closer to reality now that Japan is officially migrating their RFID frequency band down to 920 MHz."

Europe's telecommunication regulators are currently exploring the possibility of assigning the 915 to 921 MHz RF band for RFID applications, in order to meet the anticipated growth in UHF RFID usage on that continent (see European Agencies Consider the Expansion of Spectrum of UHF RFID). In May of this year, the European Union's Frequency Management Working Group (WGFM) requested that the Spectrum Engineering Working Group (WGSE) undertake compatibility studies. At the same time, WGFM approved a roadmap outlining the steps required for the Electronic Communications Committee (ECC) to recommend the designation of additional spectrum at UHF for use both by RFID and other types of short-range devices. (The ECC is part of the European Conference of Postal and Telecommunications Administrations, a coordinating body for the telecommunications regulators of 48 European countries.)

"The roadmap states that, provided there are no unforeseen issues, WGFM will publish the regulation for the designation of the spectrum in 2014," says John Falck, the chairman of ETSI's Radio Spectrum Matters Task Group 34. In parallel with the work being undertaken by ECC, ETSI will draft a new version of its EN 302 208 standard, which will include specifications for the operation of RFID in the additional band of 915 to 921 MHz.

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