Ultra-Wideband (UWB) wireless technology has been around for years, but its commercial adoption has only recently spiked. This is largely due to the attach rate of UWB in smartphones, which has reached critical mass, in addition to the demand for applications that require accurate distance measurements and secure access.

UWB uses short pulses that are only a few nano-second wide for Time-of-Flight (ToF) measurements, which determine the distance between a UWB-enabled device such as a key fob or a smartphone and a UWB-enabled asset, such as a car, by accurately measuring the time it takes for a signal to travel between the two. This method is highly secure because time is much harder to tamper with or replicate compared to relying on signal strength to calculate distance. In addition, the Scrambled Timestamp Sequence (STS) field in UWB packets enhances security. By encrypting the timestamp sequence using AES-128 encryption, only the sender and the receiver can decode the packets with the shared key, making it more difficult for unauthorized devices to intercept and manipulate the signals. This adds an extra layer of security to UWB communication, ensuring that only the legitimate, authorized key can access protected assets. This makes UWB ideal for secure-ranging applications and real-time location systems, including digital keyless access for cars, hotel rooms and hands-free payment.

UWB performance relies heavily on the quality of the semiconductors used in a device, the antenna design and the quality of calibration. That means that rigorous testing throughout design validation, calibration and manufacturing is vital to prevent defects that can cause costly product failures and recalls.

UWB standards are evolving rapidly, with major developments in standardization bodies and industry consortia. UWB was re-established as a fine-ranging technology, and the IEEE has been enhancing UWB functions such as ranging and security, which are crucial for its adoption in consumer and industrial sectors. The FiRa Consortium is expanding the UWB ecosystem in consumer applications and the Car Connectivity Consortium (CCC) is pushing forward new Digital Key specifications for vehicle access that include UWB. 

This active development landscape is shaping UWB for widespread use in personal and commercial applications, requiring ongoing attention from developers and test vendors.

Three standards and consortium groups lead the way

The IEEE’s 802.15 Working Group develops and standardizes UWB technology. It is responsible for specifying MAC and PHY standards and making amendments to the standards for further improvements. 

As part of its commitment to “fine ranging” technologies, the FiRa Consortium is creating standards and certification programs to ensure UWB device interoperability and reliability while building and promoting a healthy UWB ecosystem. The FiRa 2.0 Technical Specifications introduced additional profiles which detail high-level functioning of UWB communication for various use cases, aiming to broaden its application scope.

FiRa is also closely collaborating with the CCC; together they formed the Joint UWB MAC PHY Working Group (JUMPWG), which focuses on developing and maintaining the UWB technology specifications used in the CCC Digital Key.

Enhancements driven by IEEE 802.15.4ab 

A new amendment to the IEEE’s UWB standard, 802.15.4ab, is at the draft stage and builds on the existing IEEE 802.15.4z amendment. Scheduled for release in 2025, the new 802.15.4ab amendment aims to enhance performance pertaining to precise distance measurement over extended ranges. It will enable accurate pinpointing of tagged objects or individuals, making it possible to locate a friend in a crowded place or identifying a lost item over farther distances.

Range extensions are achieved by two techniques that are proposed to be implemented in 802.15.4ab. The first is called Narrowband Assist (NBA). As the name indicates, it lets UWB devices delegate tasks such as frequency and timing synchronization to narrowband signals (as opposed to the wideband 500MHz bandwidth of UWB) prior to exchanging UWB ranging messages. The narrowband signal operates at lower frequency than UWB and is allowed a higher transmit power, extending range. Moreover, its transmission is inherently less susceptible to noise because of its narrow bandwidth. This improves the synchronization between UWB devices, even at farther distances, hence NBA can extend initial synchronization ranges of UWB devices. 

The other technique is called Multi-Millisecond (MMS). In the current implementation, UWB ranging is completed using three packets (ping-pong-ping) in double-sided two-way ranging (DS-TWR). However, in the MMS implementation, each UWB packet can be divided into up to 16 shorter fragments. Each fragment of transmission has its power boosted, but without violating any regulatory specifications. The receiving UWB device obtains aggregated information from these fragments, resulting in a combined energy that is higher than the original UWB packet. This increased energy enables UWB devices to achieve greater ranging distances.

These advancements will improve operating efficiency and enable UWB devices to increase distance without violating regulatory emission limits and operate under Part 15 of the FCC, ETSI and other regulatory rules. 

Other key improvements in 802.15.4ab include new data-rate and sensing support. The UWB devices will dynamically adjust data rates based on environmental noise levels, for example lowering rates in noisy environments to improve communication robustness. On the other hand, higher data rates open doors for new UWB applications such as audio transmission between headsets and smartphones. Sensing or RADAR capabilities are standardized to support applications such as presence detection and environment mapping. 

UWB innovation from FiRa 2.0

The FiRa technical specifications are developed by the FiRa Consortium to ensure interoperability of UWB chipsets, devices, and equipment from different manufacturers, promoting a healthy and robust UWB ecosystem. The FiRa 2.0 Technical Specifications were launched last fall. These included more security test cases such that the FiRa-certified devices have gone through rigorous tests to improve the security of UWB devices and prevent attacks from hackers. In addition, FiRa 2.0 technical specifications enable new use cases that promise to transform interactions in personal and public spaces, improving safety and user engagement. The three new use cases that the specifications focus on are:

• Untracked Indoor Navigation extends the current implementation of indoor navigation with its centimeter-level accuracy and the way the messages are transmitted from the anchor device to the user device such as a smartphone. The user device calculates its own location by receiving UWB signals from anchor devices within the building, which makes it ideal for navigating large indoor venues like malls and airports while maintaining the user’s location privacy.
• Find Someone/Something significantly improves the ability to locate people and objects in crowded environments, such as festivals, or dense environments like parking lots, surpassing traditional GPS in location positioning accuracy.
• Point and Trigger allows users to control UWB-enabled devices, like home appliances or entertainment systems, by simply pointing at them with a smartphone or smartwatch, taking advantage of UWB’s precise angle measurement capability.

CCC and its Digital Key are tapping into UWB

Digital Key was developed by CCC to allow mobile devices to securely authenticate and share digital keys for vehicles across different manufacturers of cars, fobs and smart devices. The CCC adopted UWB, Bluetooth Low Energy and Near Field Communications (NFC) (as a backup for low-battery situations) as the wireless standards for its Digital Key 3.0 hands-free, location-aware keyless access. This allows drivers to safely unlock and start their vehicles wirelessly.

Source: Connected Car Consortium; Mobile Device Architecture

UWB is enhancing Digital Key 3.0 by making it more secure with its precise distance measurement accuracy and built-in encoding. FiRa is working with the CCC by contributing to the new Digital Key certification, a collaboration that is critical to maturing UWB by pushing carmakers and chipset vendors to work in lockstep. The new certification program, to be released later in the year, will further cement the relationship between the two consortia, while the UWB chipset and module makers, Tier 1 vendors, and car manufacturers can take advantage of similar, rigorous interoperability certification programs to ensure the devices work together seamlessly.

Testing and UWB

In the past, the cost of testing significantly impacted UWB technology. Many device manufacturers relied solely on go/no-go tests during production. However, as UWB is deployed in increasingly diverse areas – such as automotive, security, smartphones and home entertainment – there is a growing emphasis on parametric testing. 

Driven by customer expectations for top quality, this approach allows for the early detection of manufacturing defects and deviations. Given the substantial costs associated with returns and repairs, ensuring flawless UWB performance is now more essential than ever.

These mission-critical devices require thorough testing, even during high-volume production. ToF is one of the most critical tests for UWB devices, as it is the unique, differentiating capability of UWB. To avoid degrading ToF measurement accuracy, each UWB device must be calibrated to minimize ToF error to compensate for delays or errors that exist in the front end components, antennas, or UWB semiconductor itself. Additionally, the device’s transmit power must be accurately calibrated to ensure compliance with regional regulatory limits. To accurately calibrate and validate the RF performance of UWB devices, the test setup must be carefully calibrated using accurate and repeatable test equipment. This ensures that the external path loss and delay offsets that exist in the setup are precisely removed.

UWB is maturing and making a difference

UWB technology has become an innovation driver in wireless communications, driving significant advancements in location tracking, precise distance measurement and enhanced security. Its growing adoption across diverse industries, from automotive to consumer electronics, highlights its potential to revolutionize both personal and commercial applications. 

Looking ahead, UWB is set to become a foundational technology that could transform how we interact with the world around us. As UWB technology evolves and the standard becomes more refined, rigorous testing will be critical to ensure the reliable performance of UWB-enabled devices.