2 - Sending Messages
Messages sent from an end device to a network server via one or more nearby gateways are referred to as uplinks.
In this book, you learn the rules and best practices to follow when sending uplinks from your end device using the LoRaWAN® 1.0.4 specification.
Sending MAC Commands
Modify Downlink Channel Frequency Answer (DlChannelAns)
The end device sends the DlChannelAns in response to the DlChannelReq command. The DlChannelReq command is sent by the network server to request a modification to the frequency used to send downlinks in the first reception slot (RX1).
The DlChannelAns is sent to indicate whether the channel was modified.
Note
The DlChannelReq and DlChannelAns commands need only be supported by end devices operating in a region with a dynamic channel plan. Check the channel plan type for the regions in which your end device will operate in Section 1.3, ‘Regional Parameters Summary Tables’ (page 24) of the RP002-1.0.4 LoRaWAN® Regional Parameters specification.
Learn more in Section 5.6, ‘Creation / Modification of a Channel’ (page 36) of the LoRaWAN Link Layer Specification v1.0.4.
Warning
To avoid loss of connectivity, after the DlChannelReq command is received, providing the device is in a region with a dynamic channel plan, the DlChannelAns response must be sent with every single uplink until a Class A downlink is received back from the network server.