Sep 23, 2020The IEEE's amended ultra-wideband (UWB) portion of the 802-15.4 standard, known as 802.15.4z and released last month, is enabling greater coding options, as well as increased integrity and location accuracy. The UWB Alliance says the 4z amendment enables companies to build more secure solutions with granular location, which can operate with several data transmission pulse rates within a single standard. The amendment includes improvements to both high-rate pulse-repetition frequency (HRP), as well as the low-rate PRF (LRP), according to Tim Harrington, the chairman of the IEEE's Task Group 4z (TG4z). This, he says, means it can be used by companies leveraging either modulation schema.
The amendment's purpose is to enable a wider range of UWB applications, including data and ranging exchanges with smartphones, key fobs and vehicles for secure wireless access, or for payment transaction solutions, though most initial deployments are in automotive access. Companies are already building out solutions using either LRP or HRP. Because wireless transmissions need to be highly secure in order to prevent man-in-the-middle spoofing attacks, Harrington adds, one of the group's major goals was to increase the integrity of distance measurements and the security of the messages.
"It's really just beginning for ultra-wideband," Harrington says. While UWB has been available for 16 years, he notes, the technology has been used until recently in niche applications. "The 4z amendment is giving UWB that capability to be generalized in wide-scale consumer applications." The release marks the start of a new era, Harrington says. Those contributing to the standard amendment as part of TG4z are primarily engineers from smartphone manufacturers, including Apple, Samsung and Huawei, as well as chip suppliers Decawave, Qorvo, NXP Semiconductors and 3DB Access. Apple also designed its own U1 chip to be 4z-compliant.
IEEE's UWB protocol amendments began as 802.15.4a in 2007 for HRP devices based on wireless personal area networks (WPAN), and 4F was added LRP in 2012. For each of these amendments, the IEEE working group added a physical layer and a media access control sub-layer to the existing 802.15.4 protocol stack. Along with the LRP, this was added to provide a simpler, low-cost version of the protocol. Development of the newest amendment began in 2018, Harrington reports, to standardize improvements that would include both HRP and LRP, while offering greater security than the existing standard.
The group then evolved in terms of participants, Harrington says. "We started with a small group," he states, after which Apple, Samsung, NXP and other major companies joined. "We would typically have 40 engineers per meeting in attendance." As the working group finalized the amendment's development, Apple's iPhone 11 was released with UWB built into all versions. This was followed by the release of Samsung's Galaxy 20 phones in August, which also include UWB technology (see UWB in iOS 13 Could Prompt Widespread Growth). Both devices use the HRP version of UWB.
BMW and Apple are now working together on a new system by which an iPhone would serve as a digital key to unlock the automaker's latest cars via UWB. In the meantime, Volkswagen, using a different approach, is implementing an LRP version for its own vehicles. The cars will come with a key fob containing a built-in UWB tag, which will transmit data securely to the car lock as an alternative to using current technology. Both solutions leverage the 802.15.4z standard. HRP employs a higher rate of transmission, allowing it to send more data at a faster speed and with a larger, more complex chip, while LRP provides a simpler, cheaper system that transmits less data, typically at a slower rate.
Numerous organizations will be leveraging the new standard, such as the FIRA Consortium, a nonprofit organization for phone-based UWB solutions whose members include Decawave, NXP and Samsung. The organization plans to deploy HRP-based solutions for non-automotive systems. The Car Connectivity Consortium is focused on smartphone-centric car-connectivity solutions, Harrington repots, while the UWB Alliance will focus on regulatory objectives. "We are each taking a different tack," he explains, "using the amendment in ways that will be most beneficial for each of our member groups." The three groups will work together with non-competing interests. "It's been critical that there be one standard as the basis for interoperability."
The 4z amendment is intended to increase UWB transmission integrity, Harrington reports, which means more granular location accuracy and greater security. In fact, security is among the primary concerns for consumer-based solutions. With sensitive data transmitting back and forth between a key and car, for instance, technology companies are looking to make solutions that would eliminate the risk of man-in-the-middle attacks. With 4z, Harrington explains, the UWB pulses are more difficult to read. Additionally, users can now require that exchanges take place only at very specific distances, which will further prevent attacks.
Beyond automotive applications, the technology is likely to be used for home access as well. FIRA member HID Global is investigating solutions for access into residences, for example. Meanwhile, Apple uses UWB for its AirDrop data-transfer service, which allows files to be sent securely between two phones. With four antennas built into an iPhone 11, users can detect the angel of arrival from one phone to another via UWB, thereby enabling a trusted communication to send data. Payment transaction processing will be another application, as individuals could pay for goods at a point of sale using a phone or another UWB device. "We see that coming in the future," Harrington states.
The IEEE working group has been preparing the amendment to the standard even as technology companies have begun building solutions leveraging it. At the same time, the UWB Alliance is working with other radio technology stakeholders in protocols such as Wi-Fi and 5G NR-U, to promote coexistence with multiple protocols as part of the 6 GHz Multi-Stakeholder Group promoted by the FCC. The goal is to optimize sharing the band, while protecting licensed operators.