Learn more about UWB and how this precise, quick, and reliable radio-frequency (RF) technology can be used to enable advanced real-time location systems and asset tracking deployments.
Ultra-wideband, or UWB, is a short-range RF technology for wireless communication that can be leveraged to detect the location of people, devices, and assets with unrivaled precision. Like other communication protocols including Bluetooth and Wi-Fi, UWB can be used to transmit data between devices through radio waves. It does so with short nanosecond pulses over an “ultra-wide” range of frequencies.
UWB technology uses billions of pulses of radio that are sent every couple of nanoseconds as a pattern across a wide frequency spectrum (at least 500 MHz or 20% of the center frequency). These signals are dispatched from a transmitter to a receiver, or amongst transceivers. The receiving device analyzes the incoming pattern and translates it into data. While this allows devices to quickly send data over short ranges, these UWB signals can also be used to accurately sense the location of devices. This makes it possible for UWB-enabled devices (like smartphones or sensors and anchors) to pinpoint a transmitting device, such as another smartphone or asset tracking tag, find its precise location, and in certain applications enable location-aware communication and services.
While recent adoption in next-gen smartphones and other technologies may make it seem like a new, cutting-edge technology, UWB has seen applied use for decades. In many years, its use was limited or restricted and most typically seen in military radar and communication applications, under the name “pulse radio”. In 2002, the FCC authorized its unlicensed use. Since that decision, UWB technology has seen great innovation and development that are beginning to unlock transformative location-based capabilities.
Many major players have begun to realize the many possibilities of UWB and have started developing or releasing UWB-enabled solutions. Among the most notable, Apple, began implementing UWB into their technology with the release of the iPhone 11, which came equipped with their new U1 ultra-wideband chip. Other companies, such as Samsung, have followed suit, implementing UWB into some of their newly released smartphones and other devices. Google is also working on developing an API that will help enable UWB powered applications in Android devices.
It is now a cost-effective option with small enough hardware components to embed in many different types of devices. The NFL even uses ultra-wideband to track the real-time location and movement of players, putting UWB chips in their shoulder pads that allow for the league to analyze how players move throughout the field during games. NXP and Volkswagen are also exploring the possibilities of using UWB in cars to allow for more secure, convenient and safe vehicle experiences. Alongside these organizations, pioneering the development of UWB technology, are a multitude of UWB hardware vendors that offer various UWB chips, anchors, and tags with different characteristics for specific use cases, as well as consortiums including the UWB Alliance and FIRA. UWB technology will soon be as ubiquitous as Bluetooth and Wi-Fi, and some experts anticipate it usurping BLE as the premier standard for short range communication and localization.
UWB has many unique advantages that have led to it swiftly setting a new standard for RF technology. It can transmit very high data rates over short ranges, and pinpoint exact location in real-time. UWB operates with a high bandwidth over a very wide frequency spectrum between 3.1 to 10.6 GHz. It also consumes very little power, allowing for affordable and efficient hardware options, such as tracking tags with coin cell batteries that can operate for multiple years without being recharged or replaced.
The reason UWB can so precisely detect location is due to its distance-based measurement via time-of-flight (ToF), that calculates location based on how long it takes for pulses of radio to travel from one device to another. While this only works over shorter ranges, the location of UWB signals can be determined with an accuracy of less than 50 centimeters (with optimal conditions and deployment), and extremely low latency. Other standards like BLE and Wi-Fi , usually cannot be used to do this, and instead typically determine location via rather unreliable received signal strength indicators (RSSI) only showing rough categories of “weak” or “strong” received signals, which grants location accuracy into the meter level.
The low transmission power and wide spectrum of frequencies UWB signals are sent with, allow for little to no interference with surrounding narrowband technologies. UWB also appears to be “invisible at noise floor”, making it a good choice for coexistence with narrowband RF technologies. These unique properties are why UWB is quickly emerging as a premier indoor positioning technology for location-based and short-range communication applications.
UWB makes it possible to determine location via ToF. This can precisely measure distance between transceivers by calculating the time it takes for signals to travel amongst the devices. In certain scenarios the X,Y, and Z coordinates of a device’s location can be detected, adding an additional dimension to the localization UWB can provide. Based on the use case or application, the exact technique of the ToF calculation can differ.
For UWB positioning, there are two primary techniques that can be used: Time Difference of Arrival (TDoA) and Two-Way Ranging (TWR).
Time Difference of Arrival (TDoA)TDoA utilizes UWB anchors or sensors that are deployed in a fixed position throughout an indoor space. These sensors then detect and locate a transmitting UWB device, such as a tracking tag. To work properly the fixed anchors need to be accurately synchronized to run on the same clock. The UWB tag, or other device will transmit signals in regular intervals. These signals will be received by any anchors in the communication range and time-stamped by the anchors. All the time-stamped data is then sent to the central IPS or RTLS.
The location engine will analyze each anchor’s data and the differences in arrival times to each anchor and use multilateration to calculate the tag’s coordinates. Those coordinates can be used to visualize the location of the device on an indoor map of your space or leveraged for other uses depending on the specific application.
Two Way Ranging (TWR)While in TDoA multiple fixed anchors work together to determine the location of a mobile object, TWR primarily uses two-way communication between two devices, such as smartphones, to sense the distance between them. With TWR, when a device is in close proximity to another, the two devices will start ranging with each other to determine their distance, even as they communicate. The time it takes a signal to travel between them is then multiplied by the speed of light and used to determine their relative positions, frequently to enable location-aware communication.
The determined location from one device to another is then harnessed depending on the specific application. TWR can also be used by fixed anchors and UWB devices, however the TWR process can only use one ranging partner to locate the device at a time.
Ultra-wideband, like each RF standard, offers unique characteristics and advantages that may make it a suitable option depending on individual needs, budget, facility, and specific location-based use case. The most critical differences between UWB and other technologies are its wide frequency spectrum and the level of accuracy it can provide. UWB’s precision makes it an effective option, particularly in advanced indoor positioning use cases such as asset tracking scenarios, where absolute location and real-time movement is crucial.
