LoRaWAN™ uplink transmission
Basic Transmission strategy
The tracker follows the LoRaWAN™ requirements regarding the transmission (like duty cycle). Each transmission is managed according to the transmit_strat parameter:
| Strategy | ID | Device is static | Device is moving(2) |
|---|---|---|---|
| Single fixed | 0x00 | Single transmission using network ADR(1) | Single transmission using the data rate configured in default_datarate parameter |
| Single random | 0x01 | Single transmission using network ADR(1) | Single transmission using a random data rate within [DR0-DR5] |
| Dual random | 0x02 | Single transmission using network ADR(1) | Double transmissions: - First transmission using a random data rate within [DR4-DR5] - Second transmission using a random data rate within [DR0-DR3]. |
| Dual fixed | 0x03 | Single transmission using network ADR(1) | Double transmissions: - First transmission using a random data rate within [DR4-DR5]. - Second transmission using the data rate configured in default_datarate parameter |
| Network ADR | 0x04 | Single transmission using network ADR(1) | Reserved, internal use only. |
| Custom strategy | 0x05 | Based on transmit_strat_custom parameter |
(1) Number of retransmission and data rate managed by the network (with the same sequence number).
(2) Tracker is considered in motion until the motion_duration timer expires.
The data rate used when tracker transitions from motion to static (with ADR) and before receiving the new data rate from the network with ADR is working as described below:
| Transmit Strategy used in motion | Data rate used when tracker is static before the new data rate is received from the network |
|---|---|
| Single fixed | the data rate configured with default_datarate parameter |
| Single random | DR0 |
| Dual random | DR0 |
| Dual fixed | the data rate configured with default_datarate parameter |
| Network ADR | No data rate change |
| Custom strategy | Minimum data rate configured in transmit_strat_custom parameter |
Refer to the section LoRa parameters for more details.
Custom Transmission strategy
It is activated only if transmit_strat parameter is set to 0x05 (custom strategy). The strategy is then defined with transmit_strat_custom parameter.
Refer to the dedicated application note AN-002_LoRa_Transmission strategy for more details. This feature should be applied only after careful study of the application note and LoRaWAN MAC behavior to not negatively impact the proper functioning of the trackers.
Confirmed uplink
The device can be configured to request LoRaWAN™ confirmations for uplink messages. The parameter confirmed_ul_bitmap is used to select the message types requiring a confirmation. Only message types in the range 0x00 to 0x0F can be selected.
Example: To enable confirmed uplink of message types 0x0 and 0x3, we need to set bit 0 and bit 3 to true. This results in confirmed_ul_bitmap = 2^0 + 2^3 = 000001001 = 9.
The parameter confirmed_ul_retry gives the number of retransmissions that the tracker should do in the case where the LoRaWAN™ confirmation is not received. A value 0 means that the tracker will request the LoRaWAN™ confirmation of the uplink message (enabled in confirmed_ul_bitmap ) but will not retry in case of a failure.