Payload size gateway vs. application

TTN Network and Services
1

Hello there :slight_smile:

I wonder why there are some differences between the payload received by the gateway and my application payload. Iā€™m sending 38 byte payload (SF12) and it is received as 51 bytes. In my application are the correct 38 bytes.

Is it due to the encryption, coding rate, padding or is it the exactly 13 byte LoRaWAN header that makes the difference?

Thank you very much :slight_smile:

2

13 bytes is LoRaWAN overhead.

MsgType | DevAddr | FCtrl | FCnt | FOpts | Port | Payload | MIC

https://lora-alliance.org/resource-hub

3 Likes
3

Thank you for your answer.

If i try to send 51 byte of application payload, will it result in 64 byte of payload displayed in the gateway traffic or will it fail because I have to add it to the LoRaWAN header and this exceeds the 51 byte limit for SF12?

4

Can noone answer my question? :frowning_face:

5

Sound like an easy experiment to attempt.
Be aware of possible MAC command answers in FOpts that could affect max app payload in a given frame.

1 Like