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 Check Answer (LinkCheckAns)
The network server sends the LinkCheckAns in response to the LinkCheckReq command which is initiated by the end device to validate connectivity. The LinkCheckAns contains the link margin in dB of the LinkCheckReq request and the number of gateways that received the request. If the LinkCheckAns is received then the end device is online, and the application running on the end device should use that information as required.
Learn more in Section 5.1, ‘Link Check Commands’ (page 29) of the LoRaWAN® Link Layer Specification v1.0.4.