What is UWB?
"UWB" stands for "Ultra Wide Band", it's a radio technology that can use a very low energy level for short-range, high-bandwidth communications over a large portion of the radio spectrum.
How it works?
In this solution, UWB Tracker will be attached to the object you would like to track, and UWB Anchor will be installed at a certain height. Currently, UWB positioning mainly uses TOF ranging, TDoA, and AoA positioning. The first two methods work independently, while the latter AoA method is usually combined with ToF or TDoA.
ToF positioning is based on range. The UWB tracker initiates ranging with each anchor that needs to be positioned. After the ranging is completed, the position is calculated. For zero-dimensional mode, it only needs to range with one anchor, for one-dimensional mode, It needs to range with at least two anchors, for two-dimensional mode, it generally needs three or more anchors for ranging, but in some special mode, two anchors are enough. For three-dimensional mode, it needs to range with four anchors.
UWB Highlights:
1. UWB covers 3G~5G, 6G~10G, a total of 7G frequency bands, and has a single channel bandwidth of more than 500MHz.
2. Low power. According to FCC and other regulations, its output power is limited to -41dBm/MHz. Based on a single channel of 500MHz, its channel power is -14.3dBm.
3. The ultra-short pulse, with a duration of a few tenths of a nanosecond.
4. Penetrating the wall: It can penetrate walls effectively but will cause some signal attenuation.
The positioning dimension is chosen based on the use case and the on-site situation. The zero-dimensional scene is mainly used for entry and exit detection. The one-dimensional scene is mainly a scene with a disproportionate aspect ratio, such as a tunnel scene, and it also works in a factory. In a one-dimensional scene, the positioned target will be aligned to a line. The 2D scene is to locate the XY coordinates without height information, while the 3D scene has height information. Still, it requires that the anchor has a height difference during system installation to ensure a certain accuracy of the Z axis.
Zero-Dimensional:
In UWB positioning, to achieve better zero-dimensional positioning is generally achieved through ranging, which is used for distance limitation, such as how far a device is from a anchor. It is considered to have entered the zero-dimensional area.
One-Dimensional:
In UWB positioning, to achieve better zero-dimensional positioning is generally achieved through ranging, which is used for distance limitation, such as how far a device is from a anchor. It is considered to have entered the zero-dimensional area.
Actual Location:
Positioning Result:
Two-Dimensional:
Two-dimensional positioning will show the XY coordinates of the target location. If the anchors are installed at the same height, the positioning results will not be affected by the installation height of the trackers.
Three-Dimensional:
The result of three-dimensional positioning is the XYZ coordinates of the target. There are two methods to achieve this. One is based on distance measurement, which requires a height difference between the anchors. The other is based on AoA, which requires a high-angle resolution on the Z axis to ensure the accuracy of the Z coordinate.
UWB
Positioning Accuracy
Accuracy mainly involves three aspects: ranging accuracy, time synchronization accuracy,
and positioning accuracy. The ranging accuracy is mainly affected by two factors: the ranging algorithm and the clock accuracy used.
1. Ranging Accuracy:
DS-TWR minimizes the error caused by clock deviation.
2. Time Synchronization Accuracy:
In the ranging system, a 0.5PPM clock temperature-compensated crystal oscillator (TCXO) can be used to achieve better accuracy. The ranging accuracy can be controlled within 10 cm. Accuracy can be improved by using TCXO.
In a UWB wireless positioning system, both ranging and TDoA are supported. In TDoA, all positioning gateways need to be synchronized wirelessly. The system has a synchronization accuracy of 0.3ns.
Compared with the wired synchronization method, a wireless system is much simpler and can be expanded without limit, and is not constrained by the wired distance. It also simplifies the difficulty of project implementation.
2. Positioning Accuracy:
It has an accuracy of 30 cm. The system’s positioning accuracy is influenced by various environmental factors, not just the distance measurement accuracy of 10 cm. The positioning accuracy of 10 cm can only be achieved in an ideal environment without any interference in the laboratory. Any signal disturbance may cause deviation to the system.
Device Involved
UWB Anchor:
It advertises beacon messages for ranging with trackers. Battery powered,5-year battery life.
UWB Tracker:
It receive beacon messages and ranging with the anchor periodically. Battery powered.
LoRaWAN Gateway:
It sends beacons messages to all anchor and trackers to sync the clock and receive distance messages from trackers.
Server:
Use the distance information and anchor’s coordinates to calculate trackers’ position. The server is also used to configure the anchor and tracker, calibrate anchor’s position and act as a positioning engine.
UWB Anchor
Advertise beacon messages
The Lansitec UWB Anchor is designed using LoRaWAN and UWB technologies. It works with surrounding UWB trackers to calculate distances between devices, regularly synchronizes time with other anchors, and transmits heartbeat data to the LoRaWAN gateway.
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LoRaWAN Gateway
Sync the clock and receive ranging messages
Lansitec Indoor LoRaWAN Gateway is an ideal product for indoor deployment with its built-in Ethernet connectivity for a straightforward setup. Additionally, there is an onboard Wi-Fi setup (supporting 2.4 GHz Wi-Fi) that allows it to be easily configured via the default Wi-Fi AP mode.
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UWB Badge Tracker
Receive messages and ranging
The Lansitec UWB Badge Tracker is designed using LoRaWAN and UWB technologies. It calculates the distance with anchors and forward the distance information to a LoRaWAN gateway to calculate its position in the server. The accuracy can be as low as 10cm.
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UWB Container Tracker
Receive messages and ranging
The Lansitec UWB Container Tracker is designed using LoRaWAN and UWB technologies. It calculates the distance with anchors and forward the distance information to a LoRaWAN gateway to calculate its position in the server. The accuracy can be as low as 10cm.
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UWB Asset Management Tracker
Receive messages and ranging
The Lansitec UWB Asset Management Tracker is designed using LoRaWAN and UWB technologies. It calculates the distance with anchors and forward the distance information to a LoRaWAN gateway to calculate its position in the server. The accuracy can be as low as 10cm.
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