UWB Knowledge Base

UWB (Ultra-Wideband) is an IEEE 802.15.4a/z standard technology optimised for secure microlocation. By measuring the time a radio signal takes to travel between devices, it can work out distance and position indoors or outdoors with unprecedented accuracy — down to a few centimetres.

Beyond centimetre-level accuracy, the standard also focuses on making UWB robust and immune to many forms of interference, ensuring high reliability. It was designed with low power consumption and low cost in mind, and it supports a very large number of connected devices.

UWB is already being used to solve problems across many industries and applications, including:

Unlike other radio technologies, UWB is purpose-built for the precise, secure and real-time measurement of position, distance and direction, while still supporting two-way communication — it was never meant to replace Wi-Fi or Bluetooth for bulk data transfer, but to add a sense of perception.

Time-of-Flight (ToF) ranging, not signal strength

One of UWB's key advantages is that it uses the time of flight of a signal to work out the distance between devices. This is far more accurate than the RSSI (received signal strength indicator) method typically used by Wi-Fi and Bluetooth.

High time resolution

UWB signals occupy far more bandwidth than common narrowband technologies. Because time and bandwidth are inversely related, UWB pulses are extremely short and their time resolution is very high, so ToF can be determined accurately. The high time resolution and short wavelength also make UWB signals far more resistant to multipath interference and fading.

Centimetre-level accuracy

Compared with radio technologies such as Wi-Fi or Bluetooth Low Energy (BLE), UWB is 100× more accurate, delivering precision in centimetres rather than metres. That matters when tracking small objects, or when you need to know which side of a wall something is on.

Ultra-low latency for real-time positioning

UWB has very low latency — on the order of microseconds to nanoseconds, versus tens or even hundreds of milliseconds for Wi-Fi and Bluetooth. UWB is 50× faster than GPS and can update up to 1,000 times per second, three thousand times faster than a standard BLE beacon. That makes it ideal for automation systems and applications involving fast-moving objects such as drones.

Wide bandwidth, high-speed communication

The wide bandwidth also makes UWB suitable for high-speed communication. And because UWB uses the ToF information and distance-bounding techniques defined in IEEE 802.15.4a/z, it offers stronger security than other wireless technologies that sense distance and position.

UWB's greatest potential lies in an entirely new generation of microlocation systems. Just as Wi-Fi and GPS paved the way for applications that were previously hard to imagine, UWB will enable experiences and features built on highly accurate position and distance sensing.

Today, people expect to locate almost anything in real time, whatever its size:

• Being guided straight to your car keys when they go missing at home;
• Getting shelf-level navigation to your favourite coffee brand in a grocery store;
• Finding a specific tool in a storage bin on a factory floor;
• As a site manager during an emergency, confirming that everyone has left the building.

In all of these scenarios microlocation helps — it does not just tell you "where" something is, it guides you to where it actually is.

UWB (Ultra-Wideband) is a wireless communication technology (based on IEEE 802.15.4a/z) characterised by transmitting narrow pulses across a wide range of frequencies, typically with an extremely short pulse width (nanoseconds). UWB uses these narrow pulses to carry data, and its transmission and modulation differ greatly from conventional carrier-based technologies such as Wi-Fi and Bluetooth.

The UWB frequency range defined by the FCC is 3.1 GHz to 10.6 GHz. Within this range, IEEE 802.15.4 defines multiple channels (Channel 0–15); the channels opened vary slightly by country and region.

UWB channel list

Chipsbank's CBU5000 series UWB SoC operates in the 6–9 GHz second band group and supports Channel 5 / 6 / 8 / 9 / 10.

As an exceptional secure ranging technology, UWB excels across five dimensions:

The table below compares the parameters of UWB, Wi-Fi and BLE positioning (for reference only):

As you can see: BLE positioning latency runs to seconds and its accuracy is metre-level; Wi-Fi is fast but power-hungry, and its positioning accuracy is also metre-level. Only UWB delivers millisecond latency + centimetre accuracy + low power at the same time.

Narrow-pulse modulation: BPSK and BPM

Unlike other radio technologies, UWB does not use amplitude or frequency modulation to encode the information its signal carries. Instead, UWB uses very short sequences of narrow pulses (just 2 nanoseconds), encoding data with binary phase shift keying (BPSK) and/or burst position modulation (BPM). These narrow pulses also have clean edges, so the time of arrival and the distance can be determined precisely even when multipath effects from reflections are present.

In the BPSK example below, two consecutive impulse radio (IR) signals represent one symbol. An IR signal can occupy one of the chip intervals (T_c) within a frame (T_f). A time-hopping (TH) code determines the precise position of the signal within its dedicated time frame, reducing the chance of interference between UWB systems. In the example, the TH codes of the symbols are {2, 1}, {2, 3} and {1, 0}, so the first and second signals are shifted by two and one chip interval respectively, and so on. Here the information corresponds to the polarity of the signal, so the IR stream represents the binary data "101".

ToF: time × speed of light = distance

Combined with the use of ToF information, this lets UWB compute an accurate distance estimate even indoors, where multipath reflections are common. Using timestamped signals, UWB calculates the time the signal takes to travel between devices, then multiplies that time by the speed of the signal (the speed of light) to obtain the distance.

The figure below shows the advantage of using ToF to compute distance indoors. In the figure, the UWB signal transmitted by the blue device reaches the grey device on the wall by several different paths. One path goes directly through the intervening wall to the grey device; the other paths are longer because they involve reflections. Because the direct path is the shortest, it arrives at the grey device first and is used to compute ToF. The other signals can be ignored. Think of it as a race: many runners reach the finish line, but only the first one wins.

This method is unaffected by signal strength, so if the direct signal is attenuated after passing through an intervening wall, the result is not affected.

To understand distance and position measurement with UWB, it is important to know the terms "anchor" and "tag". An anchor is typically a fixed UWB device at a known position. A tag usually means a mobile UWB device. Anchors and tags exchange information to establish the distance between them. By communicating with multiple anchors, the precise position of a tag can be determined. Some devices can act as anchor, tag, or both — for example, when two phones use UWB to work out the distance between them, they may alternate between the tag and anchor roles during the process.

Two-Way Ranging (TWR) determines the time (ToF) a UWB radio signal takes to travel back and forth between tag and anchor, then multiplies that time by the speed of light to compute distance. Keyless car entry systems are a classic example of using TWR for secure and accurate distance determination.

Single Sided – Two Way Ranging (SS-TWR)

The transmitter (A) sends a Poll signal to receiver B.

δ_reply is the time from B receiving the signal to sending its response — effectively the processing time (delay) inside the receiver. Since ToF_A→B = ToF_B→A, the transmitter knows the total time from transmission to reception.

Therefore: δ_loop = 2 × ToF_A→B + δ_reply

So we can compute ToF_A→B = (δ_loop − δ_reply) / 2, and hence the distance: distance = ToF × speed of light.

DS-TWR: Double Sided Two-Way Ranging

SS-TWR is simple, but the clock reference difference between transmitter and receiver introduces ToF error. Chipsbank has done extensive development work to address this shortcoming of SS-TWR by compensating for the clock error: clock frequency error is generally at the ppm level and can be compensated down to ppb. When signal strength is poor, ranging error exceeds 2 m without compensation; with compensation we can reduce the error to less than 2 cm.

If Chipsbank's clock compensation scheme is not used, Double Sided Two-Way Ranging (DS-TWR) can solve this problem, as shown below.

Each device can compute its own ToF, and then improve measurement accuracy by compensating for the clock differences between the two devices.

This method consumes more power because it involves the transmission of three frames.

TDoA: Time Difference of Arrival

Time Difference of Arrival (TDoA) is a highly scalable way to determine the position of tags within a venue. Because a tag only needs to transmit once during the whole process, it consumes very little power and therefore has a very long battery life.

Multiple anchors are deployed at fixed, known positions and tightly time-synchronised. When a mobile device sends a "beacon" or "blink" signal, every anchor that receives it timestamps the arrival against a common synchronised time base. The timestamps from the anchors are then forwarded to a central location engine, which runs multilateration algorithms to determine the device's position from the differences in arrival time at each anchor. The result is a 2D or 3D position of the mobile device, as shown below. This method is commonly used in RTLS (Real Time Location Systems).

Reverse TDoA: a GPS-like mode

Reverse Time Difference of Arrival (Reverse TDoA). A reverse TDoA system similar to GPS can also be implemented. The anchors transmit synchronised blink signals (with fixed, known offsets to avoid collisions), and the mobile devices use TDoA and multilateration to compute their own positions, as shown below.

PDoA: Phase Difference of Arrival

Phase Difference of Arrival (PDoA) lets two devices work out their relative position without any other infrastructure, using a combination of distance and direction information. This matters for peer-to-peer applications, or for reducing the amount of infrastructure that has to be deployed.

For PDoA, one of the devices must carry at least two antennas. When that device receives a signal from the other device, it measures the phase difference of the arriving signal at each antenna and converts the measured phase difference into a distance difference: P = λ × Δφ / (2π). With the distance obtained from time of flight, the rest is high-school mathematics — a few equations give the direction of the incoming signal.

The receiving device now knows the direction and distance of the transmitting device — the physical basis for "spatial awareness" interactions such as connecting to whichever device a phone is pointed at. Chipsbank's CBU5000 1T3R architecture can further deliver 3D AoA (three-dimensional angle of arrival).

The market is at an inflection point: UWB is moving from flagship experimentation to large-scale deployment, and mainstream vendors are making UWB standard on phones, wearables, automotive digital keys and trackers. Below are the latest developments from the major vendors in 2025–2026 (from public reporting and vendor announcements).

Chip vendors and standards progress

UWB is spreading across more markets. ABI Research forecasts that global shipments of UWB devices will grow at a compound annual growth rate of 14% over the next five years, from 435 million units in 2023 to nearly 1.3 billion in 2028. Chip suppliers, large and small, recognise the opportunity UWB represents.

Last year, 21% of smartphone shipments included UWB technology, including phones from Apple, Samsung, Google and Xiaomi; according to ABI Research, by 2028 almost half of all smartphones will include UWB.

Application market distribution

UWB applications span multiple markets: IoT, automotive, wearables, smart home, consumer electronics, home entertainment and connected home devices, portable consumer electronics, networking, PCs and their accessories, smartphones and feature phones, and more. As a secure short-range wireless tool with centimetre-level accuracy, every new product launch and every new market entrant continues to validate the potential and the prospects of this technology.

UWB will quickly become part of our daily life and work. The range of application scenarios includes:

The UWB technology family keeps evolving on top of the IEEE 802.15.4 standard: 4a introduced the HRP-UWB PHY for ranging and positioning; 4z strengthened secure ranging on that basis; and 802.15.4ab is best described by the phrase "capability expansion". If 4z was about whether the measurement is secure, 4ab asks: now that UWB is in phones, cars, IoT, smart homes and industry, what further capabilities are needed to support the next generation of short-range wireless applications?

What 4ab enhances

802.15.4ab enhances the UWB PHY, MAC and related ranging techniques while remaining backward compatible with ERDEV (Enhanced Ranging Capable Devices, introduced in 4z). The scope of the enhancements is very broad:

• Extensions to coding, preamble and modulation schemes;
• New operating frequencies and interference mitigation (coexistence);
• High-integrity ranging and low-power mechanisms;
• Narrowband assist;
• UWB sensing (radar-style sensing);
• Low-power low-latency streaming and high-data-rate streaming.

Four device capability classes for HRP-UWB

Building on the HRP-ERDEV of 4z, 4ab further defines and strengthens HRP-EMDEV, and introduces HRP-SDEV, HRP-ARDEV and HRP-LLDDEV, pushing UWB from "ranging" towards a "multi-capability platform":

The FiRa Consortium is a member-driven organisation dedicated to transforming the way we interact with our environment by exploiting the secure, precise positioning capabilities of ultra-wideband (UWB) technology, giving people and devices precise location awareness. FiRa ensures interoperability between different chips, devices and solutions by advancing technical specifications and certification, advocating effective regulation, and defining a broad set of UWB use cases.

Conventional UWB applications usually involve two devices communicating, computing distance from the signal's time of flight and optionally determining direction with multiple antennas. UWB radar works differently: the device actively transmits ultra-wideband pulses and simultaneously receives the reflections from people, vehicles, furniture and walls. By analysing how the continuous reflected signal changes, it works out what is happening in the space.

Four characteristics of UWB radar

Industry progress: from positioning to converged sensing and interaction

FiRa released the Core 4.0 specification and certification program in 2025, continuing to advance interoperability and ecosystem adoption among UWB devices. The industry is also exploring UWB for presence detection, child presence detection (CPD) in vehicles, micro-motion sensing such as breathing, and contactless interaction in smart homes and consumer electronics. UWB is evolving from a technology that "finds devices" into a capability that lets devices understand a user's position, behaviour and spatial state.

Chipsbank's UWB radar progress

Around the deployment of UWB radar in consumer electronics and smart spaces, Chipsbank has completed multiple solution validations and continues to advance the optimisation of algorithms, antennas, mechanical design and overall user experience:

• Outdoor two-wheeler sentinel radar: senses whether someone is approaching the vehicle, whether a target has entered a defined area and how it is moving, assisting with parking, charging, parked-vehicle watch and anti-theft alerts; it can trigger alarms, lights and cameras without depending on a camera.
• TV pointing and radar working simultaneously: lets a TV maintain spatial awareness while supporting remote-control pointing interaction, better understanding the user's intent, so that positioning, pointing and radar sensing cooperate rather than working independently.

Explanations of some terms commonly seen in the UWB field: