UWB, Digital Keys, and the Quest for Greater Range

Ultra-Wideband (UWB) technology is rapidly becoming a household name, and for good reason. This isn't just another wireless standard, it's a game-changer for how we interact with the world around us.

From finding your lost keys with pinpoint accuracy to securely unlocking your car without lifting a finger, UWB is making our lives more convenient and secure.

The Rise of UWB and the Major Players

At its core, UWB is a wireless communication technology that excels at high-precision localization. Unlike other wireless technologies that rely on signal strength, UWB uses short, low-energy pulses to measure the time it takes for a signal to travel between devices. This "time-of-flight" measurement allows for incredibly accurate distance calculations, making it ideal for applications where precision is paramount.

This potential hasn't gone unnoticed by the tech giants. Apple was a key early adopter, integrating UWB into its iPhones starting with the iPhone 11. Since then, other major players like Samsung, Google, Xiaomi, and Huawei have followed suit, making UWB a standard feature in their latest smartphones, smartwatches, and other wearables. This broad hardware adoption is backed by native support in the world's leading mobile operating systems, including Apple's iOS, Google's Android, and Huawei's HarmonyOS, creating a rich and rapidly expanding ecosystem for UWB-powered applications.

Standardization and the Digital Key

The current generation of UWB technology is built upon the IEEE 802.15.4z standard. A key feature of this standard is that it defines not only high-precision ranging but also integrates robust security directly into the physical communication layer (PHY). This makes UWB ranging inherently secure and resistant to common wireless attacks like relay attacks.

This powerful combination of precision and security provides the foundation for several key industry consortiums that are driving UWB adoption, including the Car Connectivity Consortium (CCC), the FiRa Consortium, and the Connectivity Standards Alliance (CSA). While FiRa works on ensuring interoperability across a broad range of UWB applications and the CSA develops its Aliro specification for UWB-powered smart door locks, the CCC has a more specific and immediately impactful goal: to revolutionize the way we use our car keys.

The CCC's Digital Key 3.0 specification leverages the secure ranging capabilities of the IEEE 802.15.4z standard, allowing you to use your smartphone as a secure digital car key. Leading vehicle manufacturers such as Audi, BMW, Hyundai, Kia, Genesis, Mercedes-Benz, Volvo, and many others have already embraced Digital Key 3.0.

The integration of UWB into vehicles is also paving the way for further innovation. Chipset vendors are now leveraging the UWB hardware required for Digital Key to serve multiple purposes. For example, innovative companies like Calterah have recently launched solutions that use the same UWB transceiver for both Digital Key and in-cabin automotive Radar. This dual-functionality enables valuable safety-critical features like Child Presence Detection (CPD), which can prevent hot car tragedies, as well as convenience features such as gesture-based kick sensors for hands-free trunk access.

Pushing the Boundaries: From Digital Key 3.0 to 4.0

Despite its many advantages, the current UWB technology, as implemented in Digital Key 3.0, has its limitations. The most significant of these are the maximum effective range and the precision of the distance measurements. In certain scenarios, these limitations can lead to a less-than-seamless user experience.

Recognizing these challenges, the CCC has been hard at work on the next generation of its standard, Digital Key 4.0. The full specification is a comprehensive suite that includes numerous new features and enhancements. Among these updates, a key change specifically targeting UWB performance is an innovative approach to address the range and precision limitations. This is achieved through a tighter integration of UWB and Bluetooth Low Energy (BLE), both of which are already mandatory components of the Digital Key 3.0 protocol. This change makes the overall process more robust and less likely to fail, especially when the UWB signal is weak at longer distances.

The Ultimate Solution: The Power of IEEE 802.15.4ab

While Digital Key 4.0 is a significant step forward, the true solution to the range and precision limitations of UWB lies in the next evolution of the underlying IEEE standard: 802.15.4ab. This new standard introduces a host of powerful features designed to dramatically improve the performance of UWB technology.

Two of the most important new features in 802.15.4ab are:

• Multi-Millisecond (MMS) packets: These packets, along with an optional Narrow Band Assistance (NBA) channel for initialization and control, allow for more robust communication over longer distances.
• New data rates: 802.15.4ab introduces new data rates that, when combined with a powerful convolutional code, provide a significant boost to the signal's strength and resilience.

Together, these new features result in a remarkable link budget improvement of approximately 20dB. In practical terms, this means that UWB devices based on the new 802.15.4ab standard will be able to communicate over much greater distances and with a higher degree of accuracy than ever before. This will open the door to a whole new range of UWB applications, from long-range asset tracking to even more seamless and secure keyless entry systems.

The future of UWB is bright, and with the continued innovation of standards like IEEE 802.15.4ab, the possibilities are virtually limitless. As this technology continues to evolve, we can expect to see it integrated into more and more aspects of our daily lives, making our interactions with the world around us simpler, more intuitive, and more secure.