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.
Channel, Data Rate, and TX Power Guidelines for Broadcasting
Data Rate
The initial data rate to use following a reset depends on whether the device was activated using over the air activation (OTAA) or activation by personalization (ABP).
A device activated using OTAA should have already set the initial data rate to the data rate that was used on the Join Request that resulted in a Join Accept being received in response, as described in section Step 3D: End Device Handles Join Accept of the End Device Activation Book. Adaptive data rate (ADR) should then be enabled to allow the network to adjust the data rate and conserve power, as described in the Implementing Adaptive Data Rate Book.
A device activated using ABP should use the lowest numbered data rate permitted in the region it is operating in. Find the data rate guidelines 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 lowest numbered data rate means the message has the highest possible chance of reaching a gateway. ADR should then be enabled to allow the network to adjust the data rate and conserve power, as described in the Implementing Adaptive Data Rate Book.
When the end device uses ADR, it may receive the LinkADRReq MAC command with the DataRate field which requests an update to the data rate used when sending uplinks. Learn how to locate and process the LinkADRReq DataRate field in section Convert and Validate Data Rate Updates of the Implementing Adaptive Data Rate Book.
Note
The end device is required to gradually reduce the data rate back to the lowest numbered data rate for its region when following the ADR backoff procedure, as described in section ADR Backoff of the Implementing Adaptive Data Rate Book. ADR backoff allows the device to regain connectivity if circumstances in the environment change, resulting in the device losing contact with surrounding gateways.