Hi all, I’m having some trouble finding a definitive answer to this by just searching the web, so I figured I’d just ask here. In order for an End Device to work in any region and with any spreading factor / data rate, what should I constrain my application payload size to. My best guess from my research is that 9-bytes is the constraint that works universally. Is that right?
https://lora-developers.semtech.com/library/tech-papers-and-guides/the-book/packet-size-considerations/ covers all angles of this question.
Hi,
I think that LoRa best practices Packet Optimisation Packet Size Considerations | DEVELOPER PORTAL (semtech.com) only covers the maximum payload for downlinks.
For uplinks there are different restrictions due to other channels which can be used. From my research results the maximum “universal” payload for EU868 (max: 51 bytes), US915 (max: 17 bytes) and CN470 (max: 23 bytes) could be 17 bytes.
But according to the TTN LoRa airtime calculator tool it should be 33 bytes for US915:
From my understanding the tool is wrong because it doesn’t take the dwell time into account. Am I right?
This airtime calculator states that 17 bytes for “US915DL” are fine: Airtime calculator for LoRaWAN (avbentem.github.io)