LoRaWAN 1.0.4 Specification in Depth For End Device Developers

This book explores in depth how to use Class B in end devices implementing LoRaWAN® 1.0.4. Class B mode enables the end device to receive downlinks at regular intervals. We teach you how to configure your end device to receive Class B downlinks using beacons and ping slots and best practices to follow to increase the chance of receiving downlinks while maintaining reasonable battery life.

Class B Mode

Devices implementing Class A are only able to receive messages from the network server directly after sending an uplink. Section Opening Receive Windows of the Sending Messages Book describes this in detail.

Class A devices may switch over into Class B mode, as described in the Enabling Class B Mode section, which allows the device to open additional receive windows during which messages can be received from the network server. By default, these windows can be opened roughly once every 128 seconds; you can increase this frequency, as described in the Increasing the Number of Ping Slots Used in Each Beacon Window section. Opening additional windows required for Class B operations consumes more power than Class A mode, but also enables a wider range of use-cases, providing it is acceptable for there to be a short delay before the message is received. For example, a Class B device may be used to shut down a valve in the event of an early earthquake warning.

A device can be programmed to switch between Classes A and B modes at different times of day or month. Alternatively, switching could be triggered using a custom application downlink, which the end device can use to determine when to change the class. Moving between classes when appropriate will result in lower battery usage than keeping the device in Class B mode permanently.

Class B mode can also be used to send firmware updates over the air (FUOTA) to one or more devices. You can read more about FUOTA in the TR002 v1.0.0 FUOTA Process Summary Technical Recommendation.