UWB: capabilities and Application Perspectives

Ultra-wideband technology, or UWB, gets in the focus of digital media or is being mentioned in relation to the flagship products of the top companies more and more often. Nevertheless, it still remains an underdog among conventional wireless technologies and suffers from a lack of media exposure.

So, this article intends to solve this injustice. It is a review that contains a brief historical perspective, a description of the general principles, methods, application fields, and use cases, and analyzes the capabilities and perspectives.

Content Overview

• About UWB technology
• History of development
• Pros and cons of UWB technology
• UWB localization methods
• Applications and use cases
• Conclusion

About UWB technology

UWB is a wireless communication technology that uses an ultra-wide spectrum of the carrier signal and allows data to be transmitted over short distances with extremely low power consumption.

According to ITU Radiocommunication Sector:

The main method of UWB communication is the transmission of a series of short pulses, each with a duration of about 1 nanosecond. And since the shorter the pulse the wider its spectrum, such pulses require a much larger (compared to narrow-band communications) bandwidth. Hence the term “ultra-wideband”.

Another feature is a very low signal level, close to the strength of radio noise. Because of this, UWB coexists with other, more traditional radio communication technologies without causing interference.

History of development

The method of pulse transmission of signals was known at the end of the 80s of the XIX century. At that time, improved versions of the spark transmitter, with which Heinrich Hertz was going to prove the existence of electromagnetic waves, were widely used in the organization of wireless communication between ships and coastal stations.

Later, during World War II, pulse radio technology was used in numerous military radars. In the 1950s, Soviet scientists, trying to improve power systems, began extensive research in this area. They were the first to understand that ultra-short pulses can transmit more information about an object, although the scope of application was still mainly military.

In the 1970s, UWB-based radar systems began to be used for civilian applications: ground scanning, buildings, positioning, collision warning, liquid level detection, intruder detection, and in mobile radar stations.

The Ross' US Patent 3,728,632, dated 17.04.1973, is considered a milestone in the development of the technology and emphasizes one of the major advantages of UWB - coexistence with common standards without interference.

In 2002, due to growing business interest, the U.S. Federal Communications Commission (FCC) approved for  regulated commercial use of the 3.1 to 10.6 GHz radio spectrum.

In 2003, the European Telecommunications Standards Institute (ETSI) published the IEEE 802.15.4 standard, which defines the physical layer (PHY) and media access control (MAC) layer for low-rate wireless personal area networks (LR-WPAN). A security-focused extension of the standard was introduced in 2020 in 802.15.4z, which introduced the physical layer PHY CSS (Linear Frequency Modulation at 2450 MHz), defined a two-way ranging method, and added a substitution cipher.

It wasn't until a few years ago, in 2019, that UWB became known to a wider end-user audience when world-renowned companies such as Apple and Samsung began introducing functionality based on this technology into their consumer segment devices.

Pros and cons of UWB technology

One of the main advantages of UWB is its resistance to the multipath effect due to its high timing resolution and short wavelength. That is why the technology is so good for distance measurement and tracking: UWB is 100 times more accurate than Wi-Fi or Bluetooth Low Energy in such tasks and provides accuracy within a few centimeters instead of a few meters.

The use of UWB, in turn, gives high resilience to frequency-selective fading when compared to Bluetooth and Wi-Fi. This makes it possible to deploy multiple UWB-based systems in the same environment without causing conflicts with other standards.

The extremely low latency makes UWB an ideal candidate for automatic positioning systems of fast-moving objects in real-time, e.g. drones.

Another key advantage is the high degree of data protection as a consequence of the low power of the generated pulses. The latest IEEE 802.15.04z-2020 change has increased data security by introducing a new physical layer of line-frequency modulation, adding encryption techniques such as scrambled timestamp and substitution cipher.

Other advantages of UWB include:

• No restrictions on the availability of the radio spectrum;
• Simultaneous support of hundreds of channels;
• Wide range of data rates: from 4 Mbit/s to 675 Mbit/s and higher, depending on the frequency;
• Inherent support of the dozens of topologies;
• Flexible use of spectrum;
• Ultra-low power consumption: 2 mW @1 Mbps, 6 μW @1 kbps;
• Low chip cost: ~2 – 5 USD for mass production.

But, of course, everything is not so smooth...

Due to the short pulse length and ultra-wide spectrum, the throughput of UWB drops much more (compared to narrowband transmission) with distance.

In theory, wide bandwidth and high power of the signal (when the latter is not limited by regulations) can interfere with existing systems and communication lines.

In addition, the availability of spectrum in a number of countries (12 countries, most of which are in the former Soviet Union) is limited by state agencies and security services. In Russia, for example, AirTags trackers are forced to use Bluetooth instead of the originally conceived UWB.

UWB localization methods

Let's look at how the technology implements one of its key advantages - ultra-precise distance determination.

Two-way ranging (TWR)

UWB uses ToF (Time-of-Flight) — the time to deliver “request-response” packets — to measure the distance between devices, rather than RSSI (Received Signal Strength Indicator), which is used in other standards.

This method calculates the distance between the tag and the anchor by determining the ToF and then multiplying it by the speed of light.

The more complex Double-Sided Two-Way Ranging (DS-TWR) implicitly corrects for clock offset errors but requires more data packets and, as a result, consumes more power:

ToF =1/2*(T1'T2'-T1T2)/(T1'+T2'+T1+T2)

Time-Difference of Arrival (TDoA)

Of course, ToF measurement using a single anchor will not give the location of the tag, but with the help of several external anchors the UWB is able to determine the two- and three-dimensional position of the tag in space within a certain area. At the same time, the tag packets are exchanged with the anchors, and the difference in the time of receiving such packets is calculated.

Depending on what is the receiving side, two topologies are recognized:

• Tag-Side Time-Difference of Arrival (TS-TDoA), like for example in GPS;
• Anchor-Side Time-Difference of Arrival (AS-TDoA).

Phase difference of arrival (PDoA)

Note that the ToF calculation only determines the distance, but not the direction. The Phase Difference of Arrival (PDoA) method solves this problem, as well as the problem with the organization of additional infrastructure. It is done with two antennas on at least one of the devices. The phase difference of the received signal on the antennas allows you to calculate the angle of arrival of the signal (Angle of Arrival, AoA).

Applications and use cases

Most of the applications of the UWB technology utilize either its fine-ranging security capabilities or a combination of both. Being, for a long time, attractive mostly for military and industrial purposes, the technology recently has found new implementation due to the current state-of-art in consumer electronics: wearables, smartphones, and smart infrastructure.

Fine ranging capabilities

With UWB pinpoint location within a few centimeters of all kinds of objects becomes real.

In healthcare, UWB helps people to find necessary services in hospitals, provides proximity-based data like patient medical records to the staff, and locates patients for caregivers. Medical assets tracking is also handy when it comes to a quick search of small items or expensive and important equipment such as defibrillators.

UWB radar properties are used in the remote measurement of vital parameters such as heart rate and breathing rate which also finds its application in smart buildings with presence detection, baby monitors, medical applications, and fall detection.

The technology has an extremely wide application in indoor navigation when guidance through different kinds of premises - shopping malls, hospitals, parking lots, production sites - is necessary.

UWB can be used during an emergency evacuation by tracking and tracing anyone remaining on-site.

Social distancing is one of the most relevant issues in the pandemic period. The UWB-enabled badges and wristbands can warn when getting close and alert when violating the safe zone with sub 10 cm accuracy.

With UWB production processes can be digitalized and optimized through tools & equipment tracking which improves item utilization rates and saves time. Production site becomes safer with anti-collision detection systems utilizing TWR method of UWB.

And of course, already widely known UWB tags attached to the key fobs or backpack and paired with your smartphone saves time finding important personal items.

Access control and passive keyless entry

With Time-of-Flight calculation, UWB ensures high accuracy in ranging as well as the security of the transmitted data, while calculating the angle of arrival (AoA) makes it possible to define the movement direction. Therefore, UWB-enabled devices can understand whether a user is approaching a locked door or leaving and determine which side of the door this is happening on.

In the case of access control, UWB is used in pair with other protocols, most commonly — Bluetooth. Bluetooth is used to initiate ranging and to transfer data, while UWB is directly responsible for ranging.

The new physical layer (PHY) added in IEEE 802.15.4z and related to cryptographic protection minimizes the success of MITM attacks. This opens up a huge number of possibilities: smart locks in apartments and garage doors, physical access control systems at production sites, rental services, digital keys for vehicles and much more.

In early 2022, Samsung in collaboration with Zigbang announced the release of a "smart door lock". To unlock this lock you do not even need to take your smartphone out of your pocket.

In January 2021, Apple announced its UWB-based digital car key feature and confirmed that it is adding a wider range of digital key and digital ID options to iOS 15 and to watchOS 8 for Apple Watch users. Google’s Pixel 6 Pro and Pixel 7 Pro also support UWB digital key, as well as Android's "Nearby Share" feature, which lets you transfer files at close range from one device to another.

Volkswagen and the world’s largest chip manufacturer, NXP keep up by offering extended functionality like recognition of the child seat presence and disabling the corresponding airbag, gesture control of the tail door, automatic detection, and extraction of the hitch for coupling with a trailer.

The refreshed BMW X5 and X6 will support the UWB digital key function, which can be shared with up to five more people through a native app.

UWB devices can form a so-called "security bubble" around a certain area, used in particular to automatically unlock personal devices. A couple of videos with a demonstration of how such "bubbles" work:

The technology can be used in a variety of WBAN applications. In health monitoring, a network of UWB sensors such as electrocardiogram (ECG), oxygen saturation sensor (SpO2), and electromyography (EMG) can be used to develop a proactive and smart healthcare system.

Multimedia, augmented, and virtual reality

The low latency value (5-10 ms for streaming audio when using codecs and up to 2 ms for uncompressed audio) makes UWB attractive for use in streaming video and audio data, in VR and AR, and various types of controllers.

UWB devices can create contextual experiences based on proximity and orientation which is used in smart retail and smart home systems.

The Apple HomePod, HomePod mini and Nest speakers from Google can instantly pick up music playing on a smartphone, a podcast, or an ongoing phone conversation when it approaches the speaker (Apple's "Handoff" feature).

One good example of a smart home device is Sevenhugs Smart Remote X. Released in 2016 this product was unfortunately ahead of its time. The set included the remote controller and anchors for defining its orientation so that the context menu of the device the remote control pointed at is called. The main disadvantage was the prohibitive price tag: $399 at the start.

Presence detectors with UWB can be used in professional lighting systems of office buildings. Switching on the light when motion is detected saves electricity, and the high sensitivity of UWB sensors can detect even the slightest movement of a person sitting quietly at a computer or phone and maintain lighting in the desired area.

Targeted marketing gives customers individual offers based on their journey route and preferences. Businesses can benefit from foot traffic and shopping behavior analytics.

Automotive

Multiple cases for automotive include:

• Driverless valet parking and pick-up: the driver can leave the car in the right place, and the car will find a place and park itself. Later, through an app on the smartphone, the driver can call the car to be served at the desired location;
• V2X * (vehicle-to-everything communication) and autonomous driving;
• Digital car key and various convenience functions, mentioned earlier;
• C2X communication (a social Network for Automobiles) may significantly decrease accidents through communications between vehicles and traffic infrastructure elements.

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“Follow me” and anti-collision features using UWB technology somehow surprisingly found application in Airwheel SR5 smart suitcase which frees the owner’s hands and behaves like a “good boy” following “the daddy” and avoiding obstacles.

Also, UWB is a leading technology candidate for micro air vehicle (MAV) applications.

Conclusion

It’s fair to say that the UWB standard is poised for a bright future ahead - in addition to numerous b2b use cases, the chances are high that soon it might become one of the standard smartphone interfaces, as it happened with the likes of Bluetooth and NFC.

Prediction of UWB market CAGR of 16.06% to USD 3.129 billion by 2026 made, as reported by “Research and Markets” in 2021 might be doubled, if not tripled, in case if UWB becomes one of a standard interfaces - it is already popping up in flagship smartphones and might make its way to mid-range soon.

At notAnotherOne, we’ve been closely looking at UWB developments and have participated in a number of UWB-powered projects,  including typical use cases, like RTLS, as well as more rare implementations of the medium, including audio streaming. Would be happy to discuss your product needs!