This article appeared in RFID Journal on January 27, 2025.

  • Companies using UHF RAIN RFID to track products or assets now have a new protocol to work with that could make tag reading faster, with unrelated tags filtered out, and access to more tag data
  • The RAIN Alliance and GS1 have been working on the new protocol for several years and technology companies are now developing hardware and software updates to leverage it

This month, standards organizations RAIN Alliance and GS1 have been introducing the RFID industry to a new UHF RAIN RFID protocol, the first that was released in a decade—one that promises better RF operation in crowded environments, improved speed and sensitivity, and better memory storage and access options.

The update, several years in the making, tasks companies with developing RFID tag chips and reader software updates to employ the benefits of the latest version of Gen2. GS1’s UHF EPC “Gen2” air interface protocol was published by EPCglobal in 2004, to lay out the technical requirements for an RFID system of interrogators and passive tags, operating in the 860 MHz to 930 MHz UHF range.

Over the past decades, UHF EPC Gen2 has been established as the standard for UHF passive RFID, which has been known under the term “RAIN” with the launch of the RAIN Alliance in 2014. The Gen2v2 version of the UHF protocol was released in 2013 following a previous update in 2008.

45.5 Billion Tags in 2023

In recent years, the use of UHF RAIN RFID has been expanding and gaining traction in some verticals. The high volume of RFID tags in everything from retail to healthcare to transportation creates a challenge related to crowded tag reads.

Today, there are tags on a wide variety of products that might respond to a tag reader in their vicinity. That creates challenges related to filtering out unnecessary tags. Additionally, users of the technology have been seeking more specific data and ways of accessing or filtering out that data from the tags that they read.

This has meant that the protocol needed upgrading, said Josef Preishuber-Pflügl, founder and owner of wireless technology company innobir, RAIN Alliance’s head of regulatory affairs and project editor of ISO/IEC 18000-63.

“There was market feedback from users, system integrators and certainly also vendors that there was room for new features to handle this new amount of tags,” Preishuber-Pflügl said.

Picking and Choosing the Right Tags to Read

GS1 and the RAIN Alliance working groups started about five years ago to plan the Gen2 upgrade and then GS1 took the lead on the update of the Gen2v3 interface in alignment with the RAIN Alliance. Updates to the related ISO standard (ISO/IEC 18000-63) also coincide with the latest version. The group put the new

Gen2v3 version through a first ballot for membership voting and it passed.

“Now basically everyone is working on getting this implemented to be able to utilize the benefits,” Preishuber-Pflügl.

Put simply: the Gen2v3 air protocol enables readers to efficiently select only the tags of interest in a population. This feature provides multiple benefits—reducing tag read clutter, improving read rates, facilitating multi-read deployments, and simplifying access to data stored on a tag’s memory banks.

Query X and Y

The first feature (clutter reduction) focuses on making it possible for a reader to capture the relevant tag reads and disregarding unrelated tag responses to an RF interrogation.

Preishuber-Pflügl pointed to a common and challenging application—reading RAIN RFID tags on luggage in an airport, when multiple items inside that luggage also have such tags. Airports often use RAIN RFID tags to identify bags, and tags inside the bags can interfere with that process.

The Gen2v3 version accommodates new commands—called Query X and Query Y—which act as a selection to allow advanced filtering out of specific tags. For instance, a user could select specific EPC schemes or specific tag features (like those provided by the airport). Then only those tags of interest would be read.

Improving Read Rates

When the reader transmits its interrogating power, it can do so at a temporarily reduced power level that only the relevant tags will respond to, while tags “on the edge” that are not specific to that tag read deployment may respond later. So an undesirable tag may still respond to the interrogation, but not until it gets closer to the reader.

Preishuber-Pflügl added this update should reduce the impact of degraded read rates caused by fringe tags on the outer edge of a read zone, helping enhance inventory accuracy. And with the new protocol, interrogators will be able to modulate the radiated field strength to ensure that tags have enough power to be properly inventoried.

Facilitating Multi-reader Deployments

In some cases deployments include multiple RFID readers interrogating tags in a specific vicinity. They may have several applications in use as well.

Case in point: a store in which inventory tracking is underway in the store’s backroom, while other readers are employed at the point of sale, and yet other readers in operation at the exit to detect tagged goods leaving the store.

Gen2v3 is designed to streamline tag read instructions from the reader to prevent misreads of tags that are being interrogated for other purposes elsewhere in the store.

Simplifying Data Storage and Access

Traditionally an EPC number uniquely identifies a tag and links to data about a product the tag is attached to. However, vendors at a tag or chip production site encode their own Tag ID (TID) which may include other features such as where and when the chip was made.

Additionally, readers—using the Gen2v3 protocol on tags that support the same protocol—can capture an indication with the EPC number that user memory is also available, and users can select how much data to capture.

Gen2v2 can instruct the tag to backscatter what is encoded, nothing more, nothing less. Gen2v3 leverages a new command called Read-Var that allows a user to select stored data to read in a more convenient and effective way.

Selecting Tag Reads

In this way, readers can efficiently read the data from the user memory. With the new functionality, the benefits could include selection of tags based on the expiration date of a medication, for instance, or identifying medication from a specific batch and manufacturer in the case of a recall.

Overall the latest protocol should allow technology to more efficiently read tags and manage data.

The new protocol results from years of collaboration between RAIN Alliance and GS1, led by Claude Tetelin, who chairs the RAIN Alliance Technical Workgroup.

To comply with Gen2v3, new RAIN RFID tag chips will be introduced, and reader manufacturers will only need to update their software. Solution providers may update their deployment implementation to take advantage of Gen2v3’s new features, but it’s not required. Gen2v3 is backward compatible, deployments operating under the Gen2v2 protocol will still function.