5 - Class B
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.
How to Send Class B Messages
Class B downlinks are sent to a device from the network server. Different network servers may offer various methods for sending downlinks to a device, such as APIs for third party integrations or a user interface for manual message submission. The network server then sends the downlink to the device using a single gateway. When the end device has informed the network server that it is operating in Class B mode, the network server will wait for a time slot before sending the message. Learn more about how these time slots are determined in the Timing of Ping Slot Windows section.
Note
The network server selects the gateway it will use by identifying which has the highest chance of ensuring the message is received by the device, based on the gateways it recently received Class A uplinks from.
Because the network server uses statistics from recent Class A uplinks it has received to select the gateway, it is important that the end device sends regular Class A uplinks to the network server. We discuss this later in the section Updating the Network Downlink Route.