Questions about positionings of the Nodes in the BLE Mesh

[NORD44]

Hello, I was wondering, 
Firstly and more important question, Is there a way in a BLE Mesh standard to physically locate/position the nodes? In order to obtain the distance of all nodes with respect to each other.
(Please note that I am not asking about tracking a moving object like a person who enters the mesh!) 

Secondly, as far as I understood in practice most of the nodes in a BLE mesh must be static or they are installed in a fixed place. Is that right? 
Lastly, is there any distinction between a node (like a smartphone) which STARTS sending a command to change the state of a group of nodes and other nodes? or this very node is just simply called a node like other nodes.

[Simonr]

Hi

1. This depends on how accurate you want this location to be. It can be done very roughly using RSSI to estimate the position of nodes, see this post. If you need a more accurate solution, I suggest you check out the direction-finding capabilities in Bluetooth 5.1. Check out these blog posts for more information on the matter. Quuppa also has direction-finding technology available that support Mesh solutions.

2. It's not necessary for the nodes in a BLE Mesh network to be stationary. As long as they're in range of the rest of the network, there shouldn't be any problem moving them around. Keep in mind though, that in larger networks, some relay nodes should be strategically placed, so that the entire Mesh network is covered.

3. Generally, smartphones don't support the Mesh protocol, as most Operative Systems won't allow 100% access to the radio. Generally, they communicate with one of the nodes in the network via "regular" BLE and make the node transmit the commands from the smartphones.

Best regards,

Simon

[NORD44]

Thank you so much Simon.
I would really appreciate it if you could shed more light on the followings:

It's become interesting! Regards point 3, so you are trying to say a smartphone cannot be part of a mesh network or in other words, it cannot be a node in a mesh network (for example it cannot take the relay role or friend role), however, it can communicate with the network, by communication mean to send and receive messages.
Is my conclusion right? And is there a list of devices which support BLE mesh?

Regards point 1. what I had in mind was to use trilateration algorithm, but I think it requires each node to be intercepted/surrounded by at least other three signals/nodes, which does not sound practical!
However, back to your response, honestly I am a little bit confused in some basics yet, 
Bluetooth mesh is another specification/standard separated from Bluetooth 5.1, but it seems that you are implying that it can use all the Bluetooth 5.1 features and still have a mesh network, is that right? 
so the mesh network is implemented on the top of Bluetooth 5.1?

Thanks again

[Simonr]

Hi

I'll start with 1 to keep it structured.

1. Yes, it seems like direction finding and Mesh will be compatible with one another according to this blog post, and I think Quuppa provides these kinds of solutions with a few of their partners. But using RSSI to get the rough estimate is by far the easiest way to accomplish what you describe I'd imagine.

3. It can not work as a relayer or a friend node, as it is dependent on a BLE connection to one single node in the mesh network. For these features the phone's OS will have to support the Bluetooth Mesh protocol.

Best regards,

Simon

[NORD44]

Thanks again.

3. Yes, as far as I understood Android and IOS devices do not support mesh protocol, but they can be used as a provisioner to add an unprovisioned device into the mesh.

However, by implementing the proxy protocol on the smartphone it can communicate with the mesh network, to send/receive messages  (like sending a message to ask about the positioning of the nodes mentioned in 1 ).

Am I got right? 

[Simonr]

Hi

Yes, most phones that support BLE are able to act as a provisioner. Generally, they can communicate with one node over BLE, and send messages via that node, and/or receive the messages that node receives from within the mesh network.

Let's say your phone is communicating with node A which is part of a larger mesh network, and you want to know the position of node B. Then (assuming this has been implemented), the phone can request the position of node B via node A. When node A receives the response containing the info of node B's position, the phone should be able to read this via node A. So yes, you're correct in that the phone can communicate with the mesh network, but it won't be a part of the network per definition.

Best regards,

Simon