measure total time required to send message from client to sever and server acknowledges that message to client using BLE MESH stack (2.0.1)

[Nikunj Patel]

Hi...,

i have measured round trip delay from client to server.

Now I want to measure total time required to send  message from server to client and client acknowledges that message to server using BLE MESH stack (2.0.1) light-switch example demo.

is it possible or Not..?

Thanks,

-Nikunj Patidar

[Nikunj Patel]

Hi

Please reply me ASAP.

[Bjørn Kvaale]

Sorry for the delayed response. This mesh blog post says this about mesh latency:

"The network latency and node power consumption depends on how much of the time is spent in scanning and advertising. The latency is on average 15ms per hop and the power consumption of the nodes is largely determined by the receive current (if everything is configured for minimum latency which means radio is on close to 100% of the time)"

It makes sense that the unreliable communication you receive for 10 bytes of data sent is slightly quicker that the reliable messages since the sender does not get an acknowledgement back from the receiver. You are not using the proxy functionality, which is good, because this would split up the radio time between mesh & GATT proxy, leading to increased latency. Have you investigated why the round trip delay is up to 2 seconds sometimes, while other times it is as low as 0.1 seconds? 

Remember that the client & server node will send health messages to the provisioner continuously. You might want to try to limit how often the heartbeat messages are sent. Take a look at Section 3.6.7 of the Mesh Profile Spec for more information about this.

Have you tried disabling the relay functionality to see if this affects the roundtrip delay? I am not sure this will have anything to say, as you only have one provisioner, one client & one server node.