We have been testing the MDEK1001 kit and have it working correctly. We have been asked about a large deployment on a big area with a big number of tags to be located. Our current estimates are near to 50 anchors and 400 tags being located at the same time. As the elements to be located are not fast moving, location and updating frecuencies are not important issues.
As described in the documentation we see that there are limits to the number of elements to be deployed:
“Tags are assigned a specific TWR slot and range to up to 4 anchors. If all the slots (there
are 15 slots in 1 superframe) have already been allocated to tags, then a new tag will be
unable to obtain a slot in which to range. In a similar way that anchors spread over space
can reuse seats when out of range of all other users of that seat, over a wider area ranging
slots will similarly be able to be reused.”
(DWM1001 System Overview. Pag 28)
Does this mean that we cannot deploy more than 15 anchors?
The need for 50 anchors comes from the wide area to cover (300m x 300m, aprox.) with big elements that limit the direct view, so many of them would not be overlaping their signals.
How is a big deployment like our planned one faced? Is there a techonologicar limitation or we can work it out with decawave devices?
Hi Blasi
I thought I had answered you on this one, but I can’t find the reply.
As you’re reading the System Overview document , please read section 4 in which is explained well that a network is not limited to 16 Anchors.
Thanks for the answer. I have gone throught the document and I am trying to understand how the protocol works. As you say, there is no such 16 anchor limit. If i am not wrong the limit is more related to what an Initiator anchor is seeing. If we set a wide area covered with anchors at a reasonable distance, setting some of them (or even all of them) as initiators would allow the whole network to be organized by itself?
As I understand if the network grows, it would be convinient to place more than one listener and bridge node.
In the document there is a reference to routing anchors. Is there an specific configuration mode for this elements or are just anchors placed between distant anchors?
In any one network only one anchor will take the role of initiator, the other anchors will join its network. In Release 2, some of the anchors will be routing anchors for backhaul data back to bridge-node/gateway. The routing anchors are set up automatically.
In any one area, you can have at most 16 anchors that are within each others range, however in practice this will rarely happen, as having so many anchors close to each other is not optimal deployment.
Similarly there are 15 ranging slots in one superframe, this means that in an area there can be at most 15 tags at 10 Hz location rate. However in a different area you can reuse slots and have another 15 tags. If you are using lower rate, then you can have more tags in an area.
To help tags roam from one area to another, you should keep capacity e.g. ~80% full so that there are empty slots for new tags to join and range to anchors.
An application could be built on top of PANS which could monitor capacity and reduce tag location rate if the capacity reaches close to 100%.