The Type 5 Tag Operation Specification provides a standardized way for NFC-enabled devices to read ISO 15693 tags, and also to write NFC Data Exchange Format messages to the tags, enabling greater functionality.

By Claire Swedberg

The NFC Forum, an organization formed in 2004 by technology companies Philips Semiconductors (now known as NXP Semiconductors), Sony and Nokia to promote the implementation and standardization of Near Field Communication (NFC) technology, has published a new spec, officially called the Type 5 Tag Operation Specification, which is intended to add support for and standardize the use of 13.56 MHz passive RFID tags compliant with the ISO 15693 standard, and to add an active communication mode for peer-to-peer communication.

Most existing NFC readers are already capable of reading and encoding ISO 15693 tags and comply with the Type 5 Tag Operation Specification. (NFC technology that allows communication with ISO 15693 tags is known as NFC-V.)

The NFC Forum's Jürgen Böhler

The NFC Forum is also releasing three candidate specifications that are updates to existing NFC specs, to include NFC-V technology and an active communication mode that the organization hopes solution providers will download, sample and provide feedback for, prior to adopting these specifications.

Until the publication of the new spec, the NFC Forum standards indicate that NFC RFID readers (such as those built into smartphones, tablets and handheld computers) be able to read four types of passive 13.56 MHz passive NFC RFID tags: Types 1 and 2, based on the ISO 14443A standard; Type 3, based on the Japanese Industrial Standard (JIS) X 6319-4, also known as FeliCa; and Type 4, compatible with ISO 14443A and B.

The NFC-V specification offers solution providers a standardized way to develop systems in which NFC-compliant readers can also read and encode ISO 15693 tags. It also provides a standardized way to instruct a reader to conduct a specific action, such as directing an NFC-enabled phone to a website, or prompting it to undertake actions such as calling for a taxi by reading a tag, and then following a prompt to make the taxi request associated with that particular phone and location. Tags operating according to the Type 5 Tag Operation specification will be known as Type 5 tags.

The NFC Forum's board of directors recently opted to adopt the new specification as a way to standardize RF communication between NFC readers and new or legacy tags compliant with the ISO 15693 standard. While numerous NFC-enabled devices already support the reading of ISO 15693 RFID tags—thereby allowing RFID solution providers to offer implementations that store messages on such tags—not every NFC-compliant reader does so.

"Some NFC-enabled devices already support communication with ISO/IEC 15693 tags," says Jürgen Böhler, the NFC Forum's Technical Committee vice-chair. "That's why it was important for the NFC Forum to develop the Type 5 Tag Operation Specification."

The NFC forum released its new specifications to broaden the range of possible implementations in the market, and to increase the interoperability with legacy devices, says Böhler, who works for STMicroelectronics as a software system architect for telecommunication and NFC chips. For example, the Type 5 Tag Operation Specification defines the mechanisms to read NFC Data Exchange Format (NDEF) messages on ISO 15693 tags.

For legacy ISO tag implementations, solution providers could expand the way in which their solutions collect and manage data. Instead of simply managing the ISO 15693 data only with their own readers, they can now add some ISO 15693 reader functionality to NFC-enabled smartphones.

For instance, a ski resort could sell lift tickets with embedded ISO 15693 tags. A skier could purchase a ticket entitling him to a specific number of lift rides—say, 10—and the solution provider could offer an app that the guest could download on his phone to manage that purchase. An RFID reader at the lift's entrance would read the ticket's tag, and the skier could use an NFC-enabled phone and the app to check how many rides are left. Each time that ticket's tag is interrogated by a ski lift's RFID reader, the system would collect that data and the reader could also write an additional message to the tag indicating how many times it had been tapped, and thus how many times the skier had used the lift. If that individual wanted to check his usage, he could then use the app to view that number by tapping his NFC-enabled phone against the ticket.

"Solution providers should now consider the new NFC-V technology for their products," Böhler says, "and are free now to choose solutions based on ISO 15693 tags when they are seeking interoperable solutions supported by future NFC devices."

One purpose of the candidate specifications now being reviewed is to add support for NFC-V technology to the NFC Forum's Analog, Digital Protocol and Activity technical specifications.

A second aim of all three candidate updates is to add support for active communication mode for peer-to-peer communication. In earlier versions of the three specs, peer-to-peer communication has been based on passive communication mode, in which the initiating generates an RF field, and the target device responds passively by modulating the initiator's RF field. In active communication mode, each peer device generates an RF field when sending information to the other end of the link, thereby balancing power consumption between the devices, while also enhancing link stability.

The Type 5 Tag Operation specification and the three candidate specs are available for download at the NFC Forum website. According to Böhler, the organization encourages companies to download the candidate specifications as soon as possible, and to review them during the coming weeks so that the NFC Forum will have time to include their feedback in the specifications' finalization. "The earlier we get feedback, the sooner we can implement it," he states.