NXP Semiconductors has confirmed that its Trimension NCJ29D6 ultra-wideband family will be deployed across the BMW Group fleet, starting with selected 2026 vehicle programmes. The same UWB silicon handles two jobs: BMW’s Digital Key Plus, which turns a smartphone or smart watch into a hands-free digital car key, and in-cabin presence detection, which uses the radio to flag a child or pet left behind in a parked car.
The announcement, made from Eindhoven on 4 August, is more interesting for what the silicon does than for the badge on the bonnet. NXP describes the Trimension NCJ29D6 as the first monolithic automotive UWB device to combine secure fine ranging with short-range radar. Carmakers wanting both have generally had to specify separate hardware, so folding them into one part changes the cost case for features that were previously hard to justify alone.
What UWB adds to the access-control toolkit
Anyone who works with RFID and NFC access control will recognise the problem being solved. Passive entry systems built on conventional key fob RF links have been picked apart by relay attacks for years, with two attackers quietly extending the link between a fob on a hall table and a car on the drive. Ultra-wideband closes that hole by measuring time of flight rather than signal strength. Operating in the 6 to 8.5 GHz range with very short pulses, it derives distance from pulse arrival time, giving centimetre-level ranging accuracy that is extremely difficult to stretch or spoof.
That secure ranging is what the Car Connectivity Consortium standardised in Digital Key Release 3, pairing Bluetooth Low Energy for discovery and session setup with UWB for the distance measurement itself. Interoperability is governed by the FiRa Consortium. Worth noting for this readership is that NFC has not been engineered out: the 13.56 MHz HF interface stays as the fallback credential, so a tap on the door handle still works when a phone battery is flat or UWB is unavailable. UWB complements the contactless credential stack rather than replacing it.
Presence detection and the NCAP timetable
The second use case is driven by regulation. Child presence detection is working its way into NCAP protocols in Europe and China, and the NCJ29D6 is positioned to meet it. The device uses UWB radar returns to identify subtle motion patterns consistent with occupant presence, then warns vehicle users that someone or something may still be in the cabin when the car is parked. NXP is careful to add that the driver retains full control of the vehicle and remains responsible at all times.
One radio, several features
The commercial logic is straightforward once the anchors are in the car. “NXP’s proven Trimension UWB platform maximizes value for OEMs, using a single system to deliver multiple new and differentiating features for drivers,” said Markus Staeblein, Senior Vice President and General Manager, Secure Car Access at NXP Semiconductors. “Digital key and presence detection are just the beginning. OEMs will be able to deliver additional UWB-based features, such as kick sensing, intrusion alert or automatic charging, as they establish the secure hardware platform in their vehicles.”
For BMW owners the visible result is a car that unlocks on approach, triggers a personalised welcome sequence and no longer needs a fob in a pocket. For the wider access-control industry it is another data point in a familiar direction of travel: short-range identification is now a layered stack, with UWB doing the secure ranging, BLE the discovery, and NFC holding the line as the credential of last resort.
Image credit: Copyright © BMW AG
