4 - Implementing Adaptive Data Rate
Adaptive Data Rate (ADR) describes the scheme whereby the network server controls the data rate, RF transmit power, and channels an end device uses when sending uplinks, as well as the number of retransmissions made.
The network server uses the Received Signal Strength Indicator (RSSI) of the messages received from the end device to determine how close the end device is to the nearest gateway(s). This allows the network server to select the most appropriate settings for each end device.
The benefits of ADR are that it helps preserve the battery life of an end device and reduces interference, giving all end devices on the network the best chance of communicating successfully.
Deciding When to Implement ADR
If your device is always static (i.e., in the same fixed location), then you should always use ADR.
If your end device is mobile, for example, if it is a geolocation tracker, ADR will not be suitable for your use case. If the device is then moved before the network server has calculated and transmitted the new settings, the settings will be unsuitable for the new location.
Mobile end devices are not necessarily in continuous motion, and they may need to send regular uplink messages during periods when they are static. During the periods when the device is static, it would benefit from using ADR. Consider designing end devices so that the application code can detect when the device is in motion. This enables you to activate ADR when the device is stationary and deactivate it when the device is in motion, optimizing battery life and network performance.
For more information, read the Adaptive Data Rate Book and Section 4.3.1.1, ‘Adaptive data-rate control in frame header’ (page 18) of the TS001-1.0.4 LoRaWAN® L2 1.0.4 Specification.