Re: [mosquitto-dev] eDRX and MQTT

[Greg Troxel <gdt@xxxxxxxxxx>]

john rubis <john.rubis@xxxxxxxxxxx> writes:

> Waking up and connecting to the broker to check for or send a message
> consumes a lot more power than for the device to wake up and quickly
> check if the network is attempting to communicate with it because it
> has a pending message to deliver to it.

I wonder what is really going on.  Are you using TLS?  It seems there
are multiple things going on:

  - the sleep of the modem vs being powered off
  - energy to reregister with the LTE network
  - energy to open a TCP connection and maybe renegotiate TLS

So I would be checking to see if you can use the eDRX method at the LTE
layer but close/open the TCP connection at the MQTT layer, and see what
happens.  Of course,  that requires you to get pre/post hook calls from
the powersave.  But perhaps if you can basically do:

   turn eDRX powersave off (to wake up LTE)
   open TCP connection to broker
   <be sure we have gotten any messages>
   close TCP connection
   enable eDRX powersave
   wait a long time

then you can get the LTE power saving of eDRX and not have TCP troubles.