Some of us might remember a little-known industry outfit back in 2004 called the UWB Forum that faded away a few years after it kicked off. Ideally, this industry organization had the goal of promoting an interoperable ultra-wideband (UWB) wireless computer networking technology based on the IEEE 802.15.3 standard. Nothing is particularly noteworthy about this as many wireless standards have emerged promising and faded into the abyss. However, like Lazarus, UWB has made a resurgence. Actually, unlike Lazarus, UWB has made another resurgence.
Where the first iteration of UWB was based on IEEE 802.15.3 and was really targeted toward a short-range wireless media standard, UWB reemerging in 2014 was based on IEEE 802.15.4a with a different vision of providing Internet-of-Things (IoT) location services and short-range wireless data transfer. Reportedly, this version of UWB was used, or at least planned for use, in a variety of automotive, defence, healthcare, and consumer applications. I am sure being a form of radar mixed with a form of short-range wireless communication sounded very attractive to military contractors, and apparently contracts were awarded to use the technology to replace wires in some U.S. Army night-vision weapon systems.
However, it seems that the 2014 version of UWB was merely fated to be a technology for asset tracking in the trucking industry, tracking NFL players during games, tracking automotive parts, and for, you guessed it, tracking aircraft tools and equipment. Though in its second life, UWB has proven somewhat successful, it has never seemed to penetrate into the consumer market or other high-profile and high-volume applications.
The latest USB incarnation
This may change with the latest iteration of UWB, the 2019 version spearheaded by the UWB Alliance and based on the IEEE 802.15.4z standard. Other consortiums and alliances are involved in this latest rendition of UWB, including the FiRa Consortium and the Car Connectivity Consortium (CCC). Like an artist who regularly reinvents himself to reflect a new age and a new sound, UWB has once again been given a facelift.
This time, however, UWB is gunning for some revenge against other wireless standards, such as Wi-Fi, which may have ultimately led to its first early demise. In this latest iteration, UWB is essentially a more capable, smaller, lower power, and less expensive version of its past self. This version of UWB uses time of flight (TOF), time difference of arrival (TDoA), and phase difference of arrival (PDoA) technologies to enable extremely accurate (~centimeter) distance/location tracking and two-way ranging capabilities.
Moreover, this latest UWB version takes into consideration new wireless technologies, such as wireless mesh networking and MIMO/beamforming, to up the ante quite a bit. By using a “mesh” of time-synchronized anchors in a venue/public space, a UWB device can be accurately tracked using a central location engine running multilateration algorithms in three dimensions. Apparently, the UWB technology is low power and efficient enough for anchors to run off of coin cell batteries for several years at a 0.1 Hz update rate and still provide centimeter-level accuracy over tens of meters (70-m typical).
Taking this a step further, UWB is also capable of two-way ranging (TWR) between two communicating devices. If additional anchors are around, the TWR feature can be augmented to include complete 2D or 3D location in real-time. If no other anchors are around and a UWB device is equipped with multiple antennas, PDoA technology can be used to provide a relative position between two different devices.
Here, UWB uses short sequences of wideband as short pulses (~2 nanoseconds) with binary phase-shift keying (BPSK) and/or burst position modulation (BPM) to encode data. The “clean” edges of these pulses allow for precision in arrival time and distance determination, even in the presence of multi-path effects. These signals are also timestamped, which is what enables the ToF distance/location capability. Hence, this new UWB is able to operate in even highly reflective indoor environments.
The FCC definition for UWB is a system that operates with an absolute bandwidth greater than 500 MHz with a maximum power density at the central frequency, which is above 2.5 GHz, or a fractional bandwidth greater than 0.2 with the center frequency lower than 2.5 GHz.
Comparing this new UWB to other short-range wireless communication standards with location capability leads to some interesting conclusions. As shown in Figure 2, UWB is more accurate, more reliable, has 27 Mbps data rate that beats all but Wi-Fi, can accommodate 10’s of thousands of tags, has a more secure physical layer that uses a distance-time bounded protocol, lower latency and lower power, and has a longer range/coverage than all but GPS. According to Qorvo, UWB can be used virtually anywhere while being at a lower price point for infrastructure, hardware, and maintenance than all but Bluetooth.
Figure 2 A comparison shows the merits of UWB, Bluetooth, Wi-Fi, RFID, and GPS technologies. Source: Qorvo
In practical applications, performance of such a system will likely be diminished somewhat. However, even if such systems are not quite as well performing, this is still impressive and could be a huge enabler for IoT technologies, especially as UWB can readily be integrated into smartphones, automobiles, 5G base stations, and throughout venues/buildings.
This is where things start to take a bit of a scary, yet exciting, turn. If UWB is cheap and energy efficient enough, it can be used to accurately track and enable communication for just about anything worth more than a tag itself. With secure communication, it can enable highly secure access and personalization services. That spans from unlocking a car (passive keyless entry) to access in controlled facilities—enabling extremely accurate AR/VR positional awareness and secure payments—to activating safety/security systems in industrial settings.
Though many of the advertised use cases are things like finding friends/families in crowded spaces, finding lost items, personalizing smart home features, and secure access to a user’s car/office, there are some other more unsettling potential use cases. Some examples include tracking employees, children in a school, and UWB radar, which is apparently capable of remotely measuring heart rate and respiration without device contact. This technology is apparently sensitive and has enough resolution to be used for contactless presence detection, baby monitors, and senior-citizen fall detection.
I am curious as to what will happen as UWB becomes more ubiquitous.
Jean-Jaques (JJ) DeLisle, an electrical engineering graduate (MS) from Rochester Institute of Technology, has a diverse background in analog and RF R&D, as well as technical writing/editing for design engineering publications. He writes about analog and RF for Planet Analog.
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