Here is the detailed behavior for Abeeway brand trackers.
Network timeout monitoring
Not receiving any downlink communication from the network is a serious symptom. It can mean that the tracker became isolated from the network, in no longer active in this network, or potentially that the device LoRa radio (or the MCU driver for it) has become unstable.
A device cannot know if lack of downlink communication from the network is due to a problem, or simply because the network or application server have nothing to say. In order to solve that problem the LoRaWAN MAC offers the LinkCheckRequest.
On Abeeway trackers the following parameters are provided:
- network_timeout_check: once this duration elapses the tracker prepends a Link Check Request to all LoRaWAN uplinks (to force the network to trigger a downlink). The associated timer is restarted each time a LoRaWAN downlink is received.
- network_timeout_reset: this duration covers the link check request period. Once elapsed without a Link Check Answer, the tracker will assume there is a problem and will reset. This will cause the device to attempt a Re-Join. We advise to keep this behavior as it is the only way to ensure that orphan devices ultimately generate very low parasitic traffic in a network (because of Join exponential back-off).
network_timeout_check= 172800 seconds (2 days)
network_timeout_reset= 86400 seconds (1 day)
If after 2 days the tracker did not receive any downlink, it starts the link check request process. After 1 day of link check request process without answers, the tracker resets.
Any downlink received by the tracker restarts the timer/mechanism. This watchdog features are disabled if you set zero values in the corresponding parameter.
Joining and exponential back-off
The LoRaWAN spec imposes a Duty-cycle for Join (common to all region), which is designed to avoid the network being locked-up in a traffic storm.
The duty cycle back-off is applied per band. For example, the IN865 region uses a single band: BAND0.
- Within the first hour, the duty cycle = 100 .
- Between the first hour and the next 10 hours, the duty cycle = 1000 seconds
- Above 11 hours, the duty cycle = 10000 seconds
Abeeway trackers follow the LoRaWAN specification, however, a button press will skip the wait timer at the application level and trigger an immediate Join. Because this is a user triggered action, it cannot cause a message storm.