RE: Bluetooth mesh group reply

TYRI — Thu, 10 Jan 2019 10:51:40 GMT

Hi Joakim!

Thank you for your answer. You're right, P is supposed to send feedback back to S and I wrote the wrong address for feedback, it should be C000, i.e.:

- have S send an unacknowledged message to C001, at which point node P is publishing its feedback message to C000, which is then received by S

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Let me rewrite the question: In short, we would like to get feedback from a group of nodes back to the sender.

We tried two cases for feedback when the nodes in a group received a message:

- let all nodes in the group simply reply to sender

- let all nodes in the group publish to another "feedback group", which the sender is subscribing to

But in both cases, the problem seems to be that feedback messages are not arriving from every node in the group (even with as little as 5 nodes in the group, at least one message may be lost). So how can we ensure that this conflict does not occur? Even though we're reducing the number of nodes in the group that send a feedback message, how many would be too many?

I suppose our question boils down to a more technical solution to avoid message congestion.

- Could it help to send messages at random delays from multiple nodes shifted? (which we've tried without much success)

- Is there any lower-level support for resending a message if it doesn't arrive (even though it's unacknowledged)?

RE: Bluetooth mesh group reply

Joakim Jakobsen — Thu, 10 Jan 2019 09:23:58 GMT

Hello.

I'm trying to understand what you setup looks like, but I might be misunderstanding.

[quote user=""]- have S send an unacknowledged message to C001, at which point node P is publishing its feedback message to C001, which is then received by S[/quote]

If Node S sends an unack'ed message to C001, Node P (subscribing to C001?) will publish a feedback message back to C001?
Do you want the other nodes subscribing to C001 to relay the message to Node S?

However, If you want to send something to a group, you should use access_model_publish (unreliable message). You still can receive response from multiple nodes if you configure those nodes to publish to your unicast address or to the group address you subscribed to.

[quote user=""]How is the situation handled if the publishing node P is lost or replaced[/quote]

I would handle this by having more than one single node sending a response. That way, if the node is lost, there is still other nodes sending a response.

Best regards,
Joakim