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.
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Fix link
In this book, you learn how to receive and handle downlink packets using the LoRaWAN® 1.0.4 specification.
Handling MAC Commands
Handling Commands That Modify Downlink Parameters
The RXParamSetupReq, RXTimingSetupReq, DlChannelReq, and TXParamSetupReq commands modify downlink parameters. There are additional rules to follow to avoid loss of connectivity when handling these commands
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The network server must be made aware of whether these commands have been accepted by the end device as quickly as possible. Connectivity will be impacted if the network server is unaware of the status of these settings on the end device. For the commands listed below, the end device must send an answer with every single uplink until a Class A downlink is received back from the network server.
Note
In addition to the commands listed in this section, the Class B Ping Slot Channel Configuration PingSlotChannelAns must also be sent with every single uplink until a Class A downlink is received back from the network server.
For other MAC commands, the end device must send back a single answer uplink.
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When devices that use Activation by Personalization (ABP) are reset, this action must not reset the configurations set by these commands that modify downlink parameters.