LoraWAN™ Message and End-Device Types

LoraWAN™ Message Types

  • Downlink – Transmission of a packet from a gateway to an end-device is known as downlink. These transmissions can be requested by a network or application server.
  • Uplink – Transmission of a packet from the end-device to a gateway is known as uplink.

LoraWAN End-Device Types

Battery Powered - Class A (All Devices)

Every transaction in a Class A end-device starts with an uplink transmission, which is then followed by two downlink-receive windows. The network server sends the downlink message after receiving the uplink. At the end of the downlink message, the end-device enters Sleep mode, thereby saving power. Therefore, Class A devices consume the least power and provide a long battery life. All LoraWAN end-devices support Class A by default. The following figure shows the data transmission and reception sequence for a typical Class A end-device:

ClassA.png
Class A Tx/Rx sequence

Low Latency - Class B (Beacon)

In Class A, the downlink is non-deterministic since it depends on random uplinks from a sleeping end-device. In Class B, the end-device reduces the downlink latency by opening periodic downlink receive windows. The periodicity of the downlink windows is maintained by synchronizing the clocks of the end-device and the network server. For the synchronization, the network server commands the gateways to send a beacon at regular intervals. During uplink, the Class B end-device behaves similarly to a Class A end-device. The Class B end-device manages to reduce power consumption and yet reduces the downlink latency. The following figure shows the data transmission and reception sequence for a typical Class B end-device:

ClassB.png
Class B Tx/Rx sequence

No Latency - Class C (Continuous)

Except for the uplink period, the end-device in Class C continuously opens the receive windows, which reduces latency, but increases its power consumption considerably. The following figure shows the data transmission and reception sequence for a typical Class C end-device:

ClassC.png
Class C Tx/Rx sequence

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