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After a successful join (join accepted message is received) the sensor will send a startup message, then starts with the normal operation and sends counter update when necessary. Some application messages (startup message, heartbeat message) are always sent as confirmed. The counter update message is not confirmed by default but can be configured as confirmed. In case of the confirmation is not received, the sensor will retry 7 more times, adapting the DataRate as recommended in the LoRaWAN v1.0.2 spec(look at 18.4 Data-Rate Adaptation during Message Retransmissions and 18.1 Uplink Timing Diagram for Confirmed Data Messages).
Count Counter update message transmission policy is configured via a table that describes the threshold for joint value of elapsed time and number of events since the last count counter update message transmission.
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Number of events since last count counter update message transmission | Elapsed time since last count counter update message transmission |
|---|---|
0 | 1200 |
1 | 300 |
2 | 200 |
5 | 100 |
10 | 60 |
The table describes a threshold in 2D space that defines if a count counter update message must be sent. If a point lies left from the curve the message must be sent.
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Number of events since last count counter update message transmission | Elapsed time since last count counter update message transmission |
|---|---|
2 | 200 |
5 | 100 |
10 | 60 |
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4.1 Expected lifespan of the car counter vs number of LoRaWAN messages per day and configured Data Rate
By configuring count counter update message transmission policy we can indirectly affect how many messages the device will send per day, and by configuring the data rate we define how much energy uses each message.
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Update transmission threshold configuration uses port 53. The configuration selected is persistent. The configuration is a table where every record represents a point of the count counter update threshold curve. If elapsed time of a record is equal to 0xFFF, this record is not used.
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Number of events since last count counter update message transmission | Elapsed time since last count counter update message transmission, seconds |
|---|---|
0 | 3600 |
1 | 60 |
2 | 40 |
X | 0xFFF - not used |
X | 0xFFF - not used |
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