3 - Receiving Messages
Messages sent from a network server to an end device are referred to as downlinks. These are sent to the end device via a single gateway. If there are multiple gateways near a device, the network server will select the most suitable gateway to broadcast from. This means the end device does not need to consider de-duping.
Devices operating in Class A mode only receive downlinks during the receive windows opened following an uplink, as described in the section Opening Receive Windows of the Sending Messages Book.
Devices that support Class B mode as well as Class A can receive additional downlinks in receive windows opened at fixed time slots. Read more about Class B mode in the Class B Book.
Devices that support Class C mode as well as Class A can receive additional downlinks at any time. Read more in the Class C: Continuously Listening for Downlinks book.
Todo
Fix link
In this book, you learn how to receive and handle downlink packets using the LoRaWAN® 1.0.4 specification.
Handling MAC Commands
End Device Transmit Parameters Request (TXParamSetupReq)
The network server requests a modification of the maximum continuous time of a packet over the air (dwell time) to a setting that is lower than the regional limitation using the TXParamSetupReq command. The maximum allowed Effective Isotropic Radiated Power (EIRP) is modified to a setting lower than the regional limitation using the same command.
Note
This command is only to be handled by end devices operating in certain regions. Find if the TXParamSetupReq command is supported in a given region in the ‘Data Rate and End-device Output Power encoding’ subsection for the region in Section 2 of the RP002-1.0.4 LoRaWAN® Regional Parameters specification.
If the TXParamSetupReq command is not supported in the region where the end device operates, the end device must not send an answer. If the command is supported, the end device must change its settings to the requested settings if they are lower than the regional limit. Find the dwell time limitation for a given region in the ‘Data Rate and End-device Output Power encoding’ subsection for the region in Section 2 of the RP002-1.0.4 LoRaWAN Regional Parameters specification. The end device then must respond using a TXParamSetupAns command, as described in section End Device Transmit Parameters Answer of the Sending Messages Book. The TXParamSetupAns is sent to confirm receipt of the request and does not contain any payload.
Learn more in Section 5.8, ‘End-Device Transmit Parameters’ (page 40) of the LoRaWAN Link Layer Specification v1.0.4.
Warning
If the TXParamSetupAns command needs sending, it must be sent with every single uplink until a Class A downlink is received back from the network server to avoid connectivity loss.
If your device uses Activation by Personalization (ABP), the settings updated by this command must not be altered when the device is reset, and therefore should be stored in non-volatile memory (NVM).
Read more in section Handling Commands That Modify Downlink Parameters.