Radio technologies come in many forms, but ultra-wideband (UWB) shows the greatest promise for emerging fields such as the Internet of Things (IoT) and the Industrial IoT (IIoT). What exactly is ultra-wideband, how does it compare with other technologies, and how can it be used to solve the many challenges faced by wireless communication?
What mainstream wireless technologies exist?
Wireless communication has been one of the most important developments in the field of electricity, dating back to 1887, when Heinrich Hertz demonstrated how radio signals can be generated from electricity and received using a spark gap and large copper wire. Modern wireless communication systems are extremely advanced with sophisticated circuitry to allow for high-speed data transfers while using small amounts of energy to do so.
Arguably the most famous wireless communication method to date is Wireless Fidelity (Wi-Fi). It is found in homes, offices, and industrial sites. Wi-Fi allows for high data rates while providing good coverage and support for multiple devices.
Cellular is the next biggest wireless communication system. It allows for handheld mobile devices to make telephone calls as well as access the internet. Cellular networks can support far more devices than Wi-Fi while also having a greater range.
Bluetooth is a wireless technology that is focused on energy and convenience. Unlike Wi-Fi and cellular networks, Bluetooth has low data-transfer rates and a very small range (a few meters); however, it uses an extremely small amount of energy. This is ideal for portable devices with batteries, as they can remain connected for extended periods of time without needing to charge.
Near-field communication is the shortest-range communication method that is widely used. Its small range of a few centimeters is beneficial for security systems that require contactless entry as well as payment methods that do not require the use of a passcode.
What challenges do wireless communication systems face in modern applications?
The past two decades have seen electronics move from wired devices to wireless devices due to the convenience provided by having no cables. The desire to eliminate cables has become so great that some electronic devices on the market now offer wireless charging.
However, the lack of cables means that devices are required to store energy so that they can operate, and this energy almost always comes from a battery. It is the reliance on a battery that creates problems for engineers when trying to implement wireless systems, as wireless communication can be extremely energy-intensive.
Devices that are required to communicate over only a few meters can make use of Bluetooth, which is very energy-conservative. However, a device that is required to send large amounts of information or be able to communicate over greater distances will need to use technologies such as Wi-Fi, which can quickly drain a battery. This is also problematic, as the battery is also required for powering screens, processors, and user I/Os.
Features such as asset tracking are also becoming increasingly popular; however, they cannot be reliably implemented with current wireless technology. GPS is not available on all devices, but even if it is, the accuracy of GPS is generally about 5 meters to 30 cm, making it totally unusable for indoor tracking. Wi-Fi can provide only about 5 meters of accuracy, while Bluetooth can give 3 meters. Future applications that require the ability to track devices in real time indoors will require far greater accuracy (less than 10 cm).
What is ultra-wideband?
Ultra-wideband is a wireless communication technology that uses a wide band of frequencies (compared with other wireless communication technologies) to transmit information.
Most typical wireless technologies modulate a carrier signal to convey information, and this modulation can either be the amplitude of the carrier wave, the frequency of the carrier wave, or the phase of the carrier wave. These methods for conveying information generally have narrow frequency ranges (i.e., bandwidth), meaning that most of their radio power is at a specific frequency. In the case of Wi-Fi, radio bandwidths are between 20 MHz to 40 MHz, centered either at 2.4 GHz or 5 GHz.
UWB, however, uses a very large bandwidth that can be in the gigahertz range, and this frequency range can easily include multiple radio technologies (such as Wi-Fi) without interfering with them.
Without getting into the complexities of UWB, it can achieve this, as the signal sent by UWB is lower than the noise floor across the entire spectrum. This does not mean that UWB transmits radio waves below the background noise level, but the amount of energy sent by UWB per unit of time is lower than a defined noise-floor limit by international standards. This can be thought of as making one loud clap per minute in a stadium. While the individual claps are very loud, the average noise per minute is almost silent.
UWB fires individual blips of radio energy across a wide range of frequencies whose wave is typically a single cycle. What makes UWB fascinating is that the generation of a single blip of energy causes the transmitter to emit over a wide spectrum (like how a square wave generates harmonics).
Millions, if not billions, of these blips are sent every second over UWB, and these blips are evenly spaced apart so that a UWB receiver can isolate the UWB signal. Furthermore, other receiver technologies (non-UWB) will naturally ignore UWB signals either because there is no frequency modulation, the radio energy is very low, or the phase shift is too narrow.
To summarize, UWB sends out tiny blips of radio energy across a wide spectrum that individually look like noise to normal receivers. These blips of energy are evenly spaced so that they can be recovered by a UWB receiver, and the average energy of UWB signals falls below the noise floor for standard communication.
What are the advantages of UWB?
UWB has many advantages when compared with existing technologies, and the development of a low-cost phased-array antenna has further helped to increase its implementation. However, it should be stated that UWB as a technology is ideal for aiding pre-existing technologies and is not designed to replace any other technology outright.
The first major advantage of UWB is extremely small energy usage. Other technologies such as Wi-Fi and cellular require the use of carrier signals over long distances, which is very energy-demanding. Reducing the energy used by the carrier wave is essentially what Bluetooth does, but this comes at a cost to the range and data-transfer rate. The use of tiny blips of radio energy helps to reduce instantaneous energy usage, while the use of a wide spectrum allows for energy to be used more efficiently (keep in mind that narrowband signals waste energy that falls outside the bandwidth).
The second major advantage of UWB is range. Depending on the frequency, radio communication can often be blocked by obstacles like walls, doors, and trees. The use of a single frequency carrier wave means that any obstacle capable of blocking signals at that frequency will result in a severe degradation of the signal (an analogy would be putting all your eggs in one basket).
UWB, however, uses a wide spectrum of frequencies, all of which behave differently and take different paths. The result is that any obstacle that can block a specific frequency will not be able to block all the other frequencies used in UWB. As such, UWB signals are exceptionally good at navigating around obstacles and can go through walls.
The third major advantage of UWB is that the use of a wide frequency range coupled with radio blips allows for advanced radar-like capability wherein UWB devices can be accurately positioned. While radio technologies such as Wi-Fi and Bluetooth can provide location accuracy of a few meters, UWB is able to do so with an accuracy of 10 cm. This allows for UWB to be used in applications that require asset tracking while simultaneously providing device communication.
In what applications could UWB be used?
When considering the advantages of UWB, it’s clear that UWB is ideal for applications that require low energy, long range, and tracking capabilities. While UWB can be used for high data rates, it is unlikely to compete with technologies such as cellular and Wi-Fi, which are specifically designed for large data transfers.
One application that UWB would be highly suitable for is IoT devices. As technology continues to improve, IoT devices will undoubtedly become smaller in size. Combine the small size with the need for remote operation and UWB becomes the perfect candidate. The low energy demands of UWB allow for IoT devices to operate for extended periods of time without needing to be recharged, while the long-range capabilities of UWB allow for IoT devices to be spread over large areas.
UWB is also ideal for applications that require asset tracking. UWB is already in use in some asset-tracking products such as the Apple Airtag, proving the capabilities of UWB. Asset tracking will also become of key importance in future industrial sites that contain hundreds, if not thousands, of internet-connected devices whose positions need to be known. For example, automated goods vehicles that shift items from one warehouse to another can utilize UWB for real-time positioning relative to other devices.
UWB also has real potential in the automotive field by utilizing the tracking capabilities of UWB to make a vehicle more aware of its surroundings. Multiple vehicles fitted with UWB systems would be able to talk to each other regarding their velocity, position, and acceleration, and this could lead to advanced safety features such as pre-emptive collision detection.
The use of UWB in vehicles could also benefit pedestrians fitted with a UWB device; cars speeding down a road could detect if pedestrians cross into traffic and either inform the pedestrian to get back or apply the brakes in a controlled manner.
Conclusion
UWB is a fundamentally different communication method compared with mainstream methods like Wi-Fi and Bluetooth. The use of radio pulses over a wide spectrum allows UWB to work simultaneously with other technologies, while the use of a wide spectrum allows for advanced features such as accurate tracking. Furthermore, the use of radio blips at defined intervals helps to reduce energy usage while retaining high data rates, and the use of large blips (albeit short in time), enables for communication up to 50 meters (putting it on par with Wi-Fi).
UWB will not replace or compete with other technologies, as each technology in use has its own advantages. However, it will undoubtedly be a major player in future IoT and IIoT applications and could even find itself useful in automotive environments.
