3 kbytes is not small for LoRaWAN. See the link Knology provided, and also see LoRaWAN Limitations on the Wiki:
The LoRaWAN no list:
- …
- Sending photos, …
And:
…
- Payload should be as small as possible. A good goal is to keep it under 12 bytes. …
- Interval between messages should be in the range of several minutes, …