WHAT IS UWB
Ultra-wideband (UWB) is a radio technology based on the IEEE 802.15.4a and 802.15.4z standards that can enable the very accurate measure of the Time of Flight of the radio signal, leading to centimeter accuracy distance/location measurement.
In addition to this unique capability, UWB offers data communication capability while using extremely little energy – enabling coin cell operation for years without needing to be recharged or replaced. By combining accurate location and communication, UWB also offers a new way of securely communicating over wireless, opening the door to new forms of secure transactions.
WHY UWB IS THE PREMIER LOCATION TECHNOLOGY
Unlike other technologies like Bluetooth or WiFi, which are being re-tooled for a new purpose, the physical properties of the UWB RF signal were specifically defined from the start to achieve real-time, ultra-accurate, ultra-reliable location and communication.
At Decawave, we also wanted UWB technology to become ubiquitous, and we added low-power and low-cost to the definition of our UWB chips.
UWB technology capabilities have opened the door to a broad range of applications. As of January 2019, more than 7 million Decawave chipsets have been deployed by more than 40 different verticals, such as:
- Factories to improve operational efficiencies or improve personnel safety
- Buildings to deliver turn-by-turn navigation services
- Cars where distance-bounding protocols are used to build secure communications between the key fob and the car to avoid car theft
- Sports to deliver real-time performance analytics
- Drones for flight control
- Connected homes to control smart devices based on the location of people
HOW UWB WORKS
UWB leverages Time of Flight (ToF), which is a method for measuring the distance between two radio transceivers by multiplying the Time of Flight of the signal by the speed of light. From this basic principle, UWB technology can be implemented in different ways based on the target applications needs: Two Way Ranging, Time Difference of Arrival (TDoA), or Phase Difference of Arrival (PDoA).
Time Difference of Arrival (TDoA) and Reverse TDoA
The TDoA method is very similar to GPS. Multiple reference points, called anchors, are deployed in a venue and are time synchronized. The mobile devices will beacon, and when an anchor receives the beacon signal it will timestamp it. The timestamps from multiple anchors are then sent back to a central location engine which will run multilateration algorithms based on Time Difference of Arrival of the beacons signals to compute the X, Y, Z of the mobile devices.
- Up to 7 years of battery life for the tag (CR2032 – 0.1Hz update rate)
- Very high density of devices – in the thousands
- Anchors need to be time synchronized
- More complex deployment
Two-Way Ranging (TWR)
The TWR method relies on two-way communication between two devices. As they communicate, the devices also measure the Time of Flight of the UWB RF signal between them. By multiplying the round trip time of the signal by the speed of light, and then dividing by 2, you can derive the actual distance between the two devices. If you apply the TWR scheme between two devices, you will get the distance (D) between the two devices. Based on the TWR scheme, you can also implement 2D or even 3D location by measuring the distance between your mobile tags and fixed beacons – this is called triangulation.
- System synchronization is not required
- Easy deployment
- Two-way communication enables downlink data and control
- Higher power consumption as devices use two-way communication – months to a year of battery life (use-case dependent)
- Limited number of mobile devices (in the hundreds)
Phase Difference of Arrival (PDoA)
The PDoA method consists of combining the TWR scheme that delivers the distance between two devices with the measure of the bearing between the two devices. The combination of distance and bearing allows the calculation of the relative position of two devices without any other infrastructure. To do so, one of the devices carries two antennas and is able to measure the Phase Difference of Arrival of the RF signal.
- Reduced infrastructure location scheme
- Relative positioning between two devices
- Location error is no longer constant, it is a function of the distance between the 2 devices
THE IEEE STANDARD
The IEEE 802.15.4a is an international standard defining the IR-UWB physical layer. This standard was designed to deliver very high accuracy location while providing simultaneous two-way communication – up to 27Mbps – to collect sensor data and control actuators. This standard was initiated in 2005 and ratified in 2007 before being fully integrated in 2011. In 2018 the standard was re-opened in the form of 802.15.4z to add further security to the physical layer as UWB is now expected to be used as a secure transaction wireless technology by the automotive and mobile industries.
Decawave CTO and co-founder Michael McLaughlin was part of the team of engineers who created the standard. This early team had the vision to make every connected object “location aware,” as they believed that “answering the where” would add huge value to the success of applications like the Internet of Things (IoT).
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THE UWB ALLIANCE
The UWB Alliance is a global, not-for-profit organization that works to collectively establish UWB technology as an open-standards industry. It serves to promote large-scale deployments and protect the millions of installed devices globally from encroaching radio technologies. The UWB Alliance is currently comprised of founding members including Decawave, Hyundai, Kia, Zebra, Alteros, Novelda, and Ubisense.
This Alliance will drive growth through end-to-end, vendor-agnostic interoperability programs that will provide accurate location, navigation, tracking, security, imaging, sensing, and communication to IoT and Industry 4.0 applications across multiple industries.
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