| LoRaWAN Header            | LoRaWAN payload (40 bytes)              |
+ ------------------------- + --------------------------------------- +
|      |  FOpts  | RuleID=1 | Compression | Payload   | Padding=b'000 |
|      |         |          | residue     |           |               |
+ ---- + ------- + -------- + ----------- + --------- + ------------- +
| XXXX | 2 bytes | 1 byte   | 21 bits     |  37 bytes |    3 bits     |