...
The first calibration initiates the join process. The Join procedure follows the Over-the-Air Activation (OTAA) described in the LoRaWAN Specification 1.0.2. Activation By Personalization (ABP) is not supported.
After powering up the car counter device, it will try to join a LoRaWAN Network by sending the join request message. In case the join request is not answered, the sensor will retry as soon as possible, according to transmission time limitations, up to 4 5 additional times (5 6 attempts in total). After the 5th 6th unsuccessful attempt, the sensor will wait with exponentially increasing intervals (see chapter 3.2) and repeat the process 5 more timesagain.
If the Join request message is not answered with a Join Accept message, the sensor retries, according to the following sequence:
Attempt | DataRate |
|---|---|
1 | Next higher datarate after Configured DR or default(DR2)( default is DR3, as the default configured datarate is DR2) but not higher than DR4 |
2 | Next higher datarate after Configured DR or default(DR2)3( default is DR3, as the default configured datarate is DR2) but not higher than DR4 |
3 | DR3 |
4 | DR2 |
45 | DR1 |
56 | DR0 |
In case the Join accept message is received after attempts 3, 4, 5, or 56(so the first 2 attempts using configured datarate failed), and the sensor's configured datarate(DR2 by default) is higher than the next slower data rate to the datarate used in the attempt, the configured datarate will be changed to DR2, DR1, DR0, or DR0 accordingly. This behavior assumes that the configured DataRate does not allow communication with the Gateway.
A few examples:
If the configured data rate was as by default DR2, and Join will be completed in attempts 1, 2, or 3(using datarate DR3 while joining) DR2 will continue to be used as configured datarate.
If the configured data rate was as by default DR2, and Join will be completed only in attempt 5 or 6(using datarate DR1 or DR0 while joining) DR0 will be selected to be used as configured datarate.
This is done to decrease the chances of selecting datarate which does not provide good connectivity.
3.2 Exponentially increasing intervals
...