[pedro_nf]

This project looks great! I don't have much time now to read your specifications etc, sorry. But I have one question: I understand that the Things can send data using low power to the cloud, how did you designed your system for the opposite direction, send data to the Thing like commands, without spending too much energy with the RF receiver? Is the receiver always ON? Is it really low low power?

[htdvisser]

That's a question we hear quite often. The LoRaWAN specification [1] defines three classes of devices. Class C nodes are powered on all the time, which indeed has consequences for the energy consumption. For more energy constrained devices, Class B offers some kind of scheduled rendez-vous, and Class A devices only receive downlink messages after (in response to) sending an uplink message. This allows nodes to switch of their radio when they don't need it.

[1]: The LoRaWAN specification be downloaded here: http://www.lora-alliance.org/For-Developers/LoRaWANDeveloper...

[IshKebab]

For comparison, BLE always uses scheduled rendezvous (B), and Thread supports always-on, and unscheduled wake-up type devices (C and A).

The downside of scheduled rendezvous is that both devices need accurate clocks, and they have to communicate regularly (once every few seconds) to maintain synchronisation.

Nice that LoRaWAN supports all three anyway.

[pedro_nf]

Thank you for your reply! I'll read the specs this week end.