Details about gateways and initiator

I have a question about the way to place initiators, anchors and gateways : in short, I do not clearly understand informations are shared between nodes.
For exemple, in the scheme below, I assume that :

  • The tag sends a broadcast UWB message to the anchors (step 1).
  • Then the anchors detect the moment when the message arrives. The anchors have to communicate this “time arrival moment” in order to calculate the location of the tag. So I assume that the anchors send this information to the Initiator (step 2 and 3 in the scheme) and then the initiator makes the calculation (step 4).
  • Eventually, the initiator sends the location information to the gateway (step 5).

    I assume that this a probably wrong but if you can describe me the “true” steps it would really help me to better understand the way UWB networks work.
    Thanks :slightly_smiling_face:

The drawing is inaccurate. I have tried to fix it, but the best way to understand the system is to read the system_overview_architecture document :

A simplified view of the system:

  • 1 - The tag send a message to 4 surrounding anchors, previously selected based on their position
  • 2-3-4 - Each anchor answers with a slight delay (so the UWB packets do not overlapp)
  • The tag calculates its position
  • 5 - The tag sends it position to gatewaym, as well as receiving/sending data from/to gateway
  • In parallel,anchors can receive/send data from/to the gateway. Note that anchors are not aware of the tag’s position.

Hope it helps,

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Yes it was very useful. I was searching for something like the system_overview_architecture document. Merci !

Thanks it was very interesting.
One extra question.
Tags and Anchor sends data to the Gateway.
Does this means that to collect data from any Anchor/Tag, the Gateway needs to have a direct connexion to those elements ? Or is there a relay done by Anchors ?

There is no relay.

Gateway will report/send data to nodes in range only. For large area, it will be required to have multiple gateways,


One extra extra question : what kind of information can be collected from the anchors since this is the tag which knows its location ? If I am not mistaken, if you only want the location, it is sufficient that the gateway sees the tag I think.


Note that the tag must be in range of at least 3 anchors to calculate its position, as well as being in range with the gateway so it can receive location data from the tag.

With this requirement, it is fairly likely the gateway will see some of the anchors seen by the tag if not all.

The advantage of having the anchors in range with gateways are that then anchors will be displayed on on web manager, and that they can be configured remotely from the gateway.


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