Issue with confirmed messages

[arjanvanb (Arjan)]

@cslorabox

it reportedly falls back to the standard SF12 eventually

True:

@arjanvanb

Now, an example has proved that, when using RX2, TTN surely is smart enough to repeat ADR on SF12 if nothing changed when the node ignored the ADR downlink in the documented SF9. The same can been seen in the code. But I feel TTN should not keep using SF12 for ADR in RX2 then; assuming your node is using the TTN specific settings that it got in the EU868 OTAA Join Accept, it will never receive the RX2 downlinks when TTN uses SF12…

On the other hand, maybe the bug is that it should not repeat forever, but only once. And maybe it uses SF9 again when the node sets ADRAckReq at some later time again. And the other nodes do accept the RX2 SF9 downlink?

So, @fhander, indeed:

@cslorabox

Key question at this point would be what the uplink SF & frequency are.

@cslorabox

Normal TTN SF9 RX2 does not seem like a strategically appropriate response to an SF12 uplink at all - I guess they are counting on hammering it with enough extra transmit power to overcome the reduced coding gain?

Also true, see:

@arjanvanb

@telkamp

in RX2 we transmit at 27 dBm, and the increase in power (over the 14dBm uplink) offsets the loss of sensitivity going from SF12 to SF9

In Slack, someone wrote that many gateways only support 20 dBm:
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