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
TX Power
Following a reset, the end device should begin broadcasting using the maximum power level it can support and is permitted for the region in which it will operate. Find the 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. Adaptive data rate (ADR) should then be enabled to allow the network to adjust the TX Power to conserve power, as described in the Implementing Adaptive Data Rate Book.
When the end device uses adaptive data rate (ADR), it may receive the LinkADRReq MAC command with the TXPower field that requests an update to the TX Power used when sending uplinks. Learn how to locate and process the LinkADRReq TXPower field in section Convert and Validate TX Power Updates of the Implementing Adaptive Data Rate Book.
Note
The end device is required to gradually increase the TX Power back to the maximum power level 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.