End Devices and Network Connectivity
An end device may lose connectivity with a network for a variety of reasons. If this happens, it can use several techniques to detect and mitigate the problem.
End devices with Adaptive Data Rate (ADR) enabled must follow the ADR backoff procedure described in the LoRaWAN specification. This procedure uses ADRAckReq and the receipt (or not) of Class A downlinks to test connectivity. This method gradually restores the end device’s default ADR configurations in a stepwise manner, with the end device finally configured to use all default channels at maximum transmit power and the lowest data rate. For fixed channel plan regions, ALL channels must be enabled. For dynamic plan regions, the default (or join) channels must be enabled, in addition to any dynamically-configured channels.
The ADRAckReq remains set. If, after an extended period following the return to the default ADR configuration, no Class A responses are received after a defined number of tries (known as the ADR_ACK_LIMIT), the end device should assume that network connectivity has been lost. In this case, OTAA devices can initiate the Join procedure again, taking into account all of the retransmission backoff procedures for any unsuccessful JoinRequests.