When doing OTAA join (ADR either enabled or disabled):
LMIC-Arduino tries to OTAA join at SB7BW125 first. If after some attempts the JOIN does not succeed it then tries at SF8BW125, if after some attempts the join does not succeed it then tries at SF9BW125. Up till SF12BW125. Then some later ADR should kick in (if ADR based changes are required).
The (LoRaMAC-node based) LoRaWAN library included with the STM32L0 Arduino core starts OTAA join at SF12BW125. Then after some time ADR kicks in to guide the node to the preferred SF/BW.
Method 1: If the node is unable to reach a(ny) gateway at SF7 but it is able to reach a gateway at SF11 then it can take quite a long time before it can actually join the network.
For distant nodes this is not very power friendly. This method is also a disadvantage for mobile (moving) nodes because the node needs to join as soon as possible (before going out of reach).
Method 2: If any gateway can pickup your signal it will probably pick up the very first join request. This will give a more or less instant join experience.
With method 2 I have actually seen ADR coming into action. I did not see ADR come into action with method 1 before (which probably depends on my situation and limited test setup).
- Two different methods. Are both methods LoRaWAN compliant?
- Which is preferred (or required) and why?