UWB Open-Loop

Unlike traditional open-loop fare collection, where each contactless card tap generates a CP transaction, the UniTiAg open-loop model is not bound by Payment Card Industry standards for CP transactions. From UniTiAg’s perspective, cEMV is just one of several authentication methods. UWB technology, widely adopted in modern smartphones, provides another way for a transit validator to authenticate the payment tool (a smartphone), verify its association with an OTRB, register a ride, and request the OTRB holder to pay via UniTiAg and CNP payments processing.

Using UWB technology, although widely supported by modern smartphones, is not possible within the classic open-loop ticketing framework because EMV specifications for UWB are not yet available.

Here’s how it works:

UWB-Enabled TSMP App

A rider downloads the TSMP App to their smartphone. In addition to TSMP-specific functions, the TSMP App is capable of communicating via UWB.

During the TSMP App startup on the rider’s smartphone and the rider’s registration with the TSMP, the TSMP App generates a pair of private and public keys:

  • The TSMP App securely stores the private key on the smartphone.
  • The TSMP App certifies its public key via the PKI certificate chain of trust, up to a CA public key, where the CA is recognized by UniTiAg.

OTRB Creation

When the rider creates an OTRB using the TSMP App, the app irreversibly hashes the TSMP App’s public key and submits it to UniTiAg in the TSMP API call “Create OTRB” as a parameter called UWB Token.
UniTiAg establishes a secure association between the OTRB and the UWB Token. This mapping is propagated to all participating ABT systems through the TA API, ensuring interoperability across the transit network.

UWB-Enabled Validators

When the rider with this smartphone and the TSMP App approaches a UWB-enabled validator, the validator first attempts to authenticate the OTRB associated with this TSMP App via the UWB channel, using the UWB Token and the PKI certificate chain of trust.
If this fails, the validator seamlessly diverts to the UniTiAg cEMV tap process, prompting the rider to tap their smartphone.

Fare Reporting and Payment

This follows the standard UniTiAg process. If the validator validates the ride with this OTRB, it reports the OTRB parameters, fare, and ride details to UniTiAg. UniTiAg makes this data available to the TSMP for further charging the rider via a CNP (or other B2C payment scheme) transaction and reconciling with the transit agency.

OTRB Updates

The TSMP App does not store the OTRB value. As usual, UniTiAg propagates the OTRB changes via its TANB API to all participating TAs while the rider is still on the trip.

Is This an Open-Loop Scheme?

This is an open-loop scheme, as UniTiAg ensures the interoperability of the same OTRB across all participating transit agencies. It is even “more open” than the classic open-loop scheme. In addition to associating an OTRB with just a cEMV card, this scheme allows associating an OTRB with any payment method supported by the TSMP.

Why UWB?

UWB’s centimeter-level precision and robust security make it ideal for transit, enabling faster validations and a frictionless passenger experience. By integrating UWB with UniTiAg’s OTRB framework, we’re paving the way for a unified, open-loop transit ecosystem that’s secure, scalable, and user-friendly.

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UniTiAg Architecture

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