AS923 - Inconsistent delay until EV_TXCOMPLETE

[pomplesiegel]

Hello all,

I have noticed that when using channel plan AS923 + ADR (or without) and TTN/TTI v3, there is a very inconsistent delay between EV_TXSTART and EV_TXCOMPLETE. Sometimes it is only ~5-6 seconds, which is consistent with the new extended RX receive period. However, sometimes it is as long as 30 seconds. Other times (very often), 15 seconds. Today it is around 8 seconds. It tends to be consistent transmit-to-transmit, and change over time when leaving a program running for a while.

I have not observed this issue for US915. Obviously this poses a concern from both a consistent transmit period and power consumption standpoint.

Anyone have an idea what could be going on here? @terrillmoore, perhaps you know?

I imagine this could be a TTN/TTI issue, but i'm not sure where to start in probing.

Thank you!
Michael

Environment

• LMIC = v4.0
• Channel plan: AS923 (testing for HK behavior)
• Gateway = Dragino LG308
• Arduino IDE 1.8.15
• TTI v3 - North America hosted
• Adafruit Feather M0 LORA

[terrillmoore]

It's either duty-cycle limitations or listen-before-talk. I don't HK has LBT, but I think it might have duty cycle restrictions. Also, the LMIC will be busy dealing with network downlinks (each of which can cause another uplink, thereby causing another 5 second delay).

Grab the code from the compliance sketch that prints out the MAC messages, and check whether you're getting a bunch of them...

Since you mention things that are multiples of 5, I suspect that TTN V3 is being chatty.

[pomplesiegel]

Great, thank you very much. I'll see if I can get the compliance logging into my code as well so I can check for this.