For several decades, the 433MHz band has quietly powered the remote key fobs that lock and unlock cars. Built around simple, low-cost transceivers operating at 315, 433, or 868MHz, these sub-GHz systems offered long range and dependable performance, ideal for an era when vehicles were mostly mechanical.

As cars have become connected, and app-driven, those systems have reached their limits. Today’s drivers expect the vehicle to recognize them automatically, unlock when they approach with a smartphone or wearable, and start with a tap. Delivering that experience requires technologies far beyond what 433 MHz can provide.

Why traditional key fobs fall short

Classic Remote Keyless Entry (RKE) systems were designed for basic commands, not context. They send encrypted messages to lock or unlock the vehicle but cannot measure distance accurately. That limitation leaves them vulnerable to relay attacks, where thieves extend or replay a signal to fool the car into thinking the key is nearby.

These systems also operate separately from the connected ecosystems that now define user experience. They do not easily integrate with mobile apps, cloud services, or software-defined vehicle architectures. To meet modern security and integration requirements, automakers are turning to new access platforms based on Bluetooth, Ultra-Wideband (UWB), and emerging local standards that provide both connectivity and proximity awareness.

The multi-radio digital key

The Car Connectivity Consortium (CCC) Digital Key Release 3 specification defines a layered system combining three complementary technologies:

• NFC for tap-to-start or backup access

• Bluetooth Low Energy (BLE) for communication and ecosystem integration

• Ultra-Wideband (UWB) for secure, centimeter-level ranging and radar

This framework lets automakers balance cost, compatibility, and security, using NFC for reliability, BLE for interoperability, and UWB for precise distance measurement and in-Cabin monitoring. China is also advancing this approach: the Intelligent Car Connectivity Industry Ecosystem Alliance (ICCE) recently added SparkLink (NearLink), a domestic short-range wireless technology, to its national digital-key standard alongside UWB and BLE Channel Sounding.

A global shift in motion

Worldwide, spectrum policy for UWB is converging around the 7–9GHz range. The U.S. FCC remains relatively permissive, while Europe and Japan have stricter emission limits. China`s regulatory frameworks are now helping set the pace for adoption.

While digital-key technologies are increasingly used to counter vehicle theft, clear policy direction and stronger manufacturing ecosystems are enabling the rapid scaling of multi-radio access technologies, including BLE CS and SparkLink.

UWB: Precision meets policy

Among next-generation access technologies, UWB offers the highest precision. It measures distance using time-of-flight techniques, transmitting extremely short pulses across wide bandwidths. This enables centimeter-level accuracy and makes relay attacks far more difficult, as attackers cannot easily mimic timing and phase data.

The same precision that secures digital keys can also support in-cabin radar functions such as child-presence detection and occupant monitoring, which are increasingly required under safety programs like Euro NCAP in the EU and the Hot Cars Act in the U.S. A single hardware platform can therefore handle both access control and safety sensing. Moreover, UWB radar can be integrated with other access technologies, for instance, BLE Channel Sounding may be adopted for vehicle entry access systems, while UWB or mmWave can be combined for in-cabin monitoring.

China’s MIIT “Interim Provisions on UWB Equipment”, released in 2024 and effective in August 2025, are expected to accelerate adoption. The regulation opens the 7.163–8.812 GHz band and removes previous bandwidth limits (not less than 500 MHz bandwidth as a minimum), aligning with IEEE 802.15.4z standards. It also authorizes Channel 11, a 1331 MHz-wide mode that enhances ranging resolution and radar penetration.

This shift offers both opportunity and complexity. Wider channels improve localization accuracy but demand advanced RF front-end design, high-speed processing, and careful power management, particularly for battery-powered devices. Chipmakers must also ensure compatibility between new wideband modes and legacy narrowband systems to support flexible deployment.

Bluetooth levels up with Channel Sounding

In parallel, Bluetooth Low Energy (BLE) continues to evolve as a secure proximity technology. The Bluetooth 6.0 Channel Sounding (CS) feature introduces phase-based ranging (PBR) and round-trip time (RTT) measurement, pushing accuracy into the tens of centimeters range. This represents a significant improvement over earlier methods that relied on signal strength (RSSI) or AoA/AoD (Angle of Arrival/Departure).

The Car Connectivity Consortium has updated its certification program to include BLE alongside UWB and NFC, allowing manufacturers to adopt the technology within existing 2.4GHz infrastructures.

Hardware support is expanding quickly. NXP’s KW47 and MCX72 families integrate BLE 6.0 with CS; while the KW45 MCUs can be upgraded from BLE 5.3 to enable the feature through firmware updates. Texas Instruments’ CC2755R10, based on BLE 5.4, includes an upgraded OTA for Channel Sounding accurate ranging (BLE 6.0 ready). However, not all BLE 5.3 or 5.4 devices support CS, as it depends on clock precision and PHY-level hardware capabilities.

Overall, BLE CS may broaden access to secure proximity features by leveraging existing Bluetooth ecosystems, complementing UWB in multi-radio digital key designs.

SparkLink (NearLink): China’s homegrown contender

Developed by Huawei and the NearLink Alliance, SparkLink (NearLink) is China’s homegrown wireless standard positioned as an alternative to Bluetooth and Wi-Fi. Operating in the 2.4GHz and 5GHz bands, it adopts advanced signaling techniques similar to those used in 5G to deliver high throughput, low latency, and strong reliability.

NearLink 1.0 (2022) introduced low-energy and high-throughput modes. NearLink 2.0 (2024) expanded capabilities for audio, human-computer interaction, and precise positioning, achieving sub-meter accuracy. With its inclusion in ICCE’s 2024 digital-key regulation, SparkLink is now an approved technology for secure vehicle access in China.