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
Link Adaptive Data Rate (ADR) Request (LinkADRReq)
The network requests adjustments to an end device’s data rate, transmission output power, channels used for uplink access, and the number of transmissions made per uplink frame using the LinkADRReq command. The end device validates the settings in the request. If valid, the end device applies the settings. The end device then queues the LinkADRAns command (containing details on which settings could be accepted) back to the network server.
Even if ADR is not currently being implemented by the end device, the LinkADRReq must still be processed, and the Channel Mask updates applied.
Read how to handle the LinkADRReq command, make the relevant updates and respond with the LinkADRAns command in section Processing LinkADRReq MAC Command of the Implementing Adaptive Data Rate Book.