In Class A LoRaWAN, the end device spends most of its time in an idle state, (that is, in sleep mode)
Periodically or Interrupt driven device wakes up and initiates an uplink, transmitting the data about the changed state back to the network (Tx).
The LoRa device then listens for a response from the LoRa Network Server, typically for one second (although this duration is configurable).
If device does not receive a downlink during the receive window (Rx1), it briefly goes back to sleep, waking a moment later, again listening for a response (Rx2), shown as below.
If no response is received during this second Rx window, the device goes back to sleep until the next time it has data to report.
The delay between Rx1 and Rx2 is configured in terms of a delay from the end of the uplink transmission.
