Understanding LoRa and LoRaWAN Class A B C : Device Classes and Differences
LoRa and LoRaWAN devices are classified into three distinct classes: Class A, Class B, and Class C. These classes define how each device communicates within a network and cater to different power consumption and latency requirements.
LoRa network composed of end devices and gateways. Based on MAC layer there are three classes of end devices in LoRa network. The classes are defined as Class A, Class B and Class C.
All the LoRa classes based end devices are bi-directional in nature for communication. Following section mentions basic features of these LoRa class types.
LoRaWAN Class A End Devices
Following are the features of LoRa Class A end devices:
• The frame in general is devided into uplink transmission and downlink transmission.
Uplink is consists of 1 slot followed by 2 downlink slots (or windows).
• Uplink slot is scheduled by End device itself based on its need. It is
decided on random basis similar to ALOHA protocol.
• It is the lowest power LoRa end device.
LoRaWAN Class B End Devices
Following are the features of LoRa Class B end devices:
• This class of end devices use extra receive windows during downlink period in addition to
two time slots specified in class-A.
• Class B devices will get extra receive windows at specified duration.
• The duration is specified by the gateway using beacon frame.
• Hence this way LoRa system indicates to the server when end device can listen.
LoRaWAN Class C End Devices
Following are the features of LoRa Class C end devices:
• This class of end devices can listen all the time except in transmit mode.
Hence it is ideal for applications requiring more downlink transmissions.
• Class C LoRa end device will utilize more power compare to Class A and Class B counterparts.
• It has lowest latency among all the LoRa class end devices for
data communication between server and end device.
LoRa Class A B C | Key differences
Following table summarizes key differences between LoRa Class A B C.
Feature | LoRa Class A | LoRa Class B | LoRa Class C |
---|---|---|---|
Communication Type | Bi-directional with scheduled uplink and downlink slots | Bi-directional with additional scheduled receive windows | Bi-directional with continuous receive window |
Latency | Highest latency due to limited downlink opportunities | Medium latency; downlink occurs at scheduled beacon slots | Lowest latency, always ready for downlink reception |
Downlink Availability | Limited to two receive windows after each uplink | Downlink is available during scheduled beacon windows | Downlink is available anytime (almost continuous listening) |
Power Consumption | Lowest, ideal for battery-powered devices | Medium, with periodic receiving during beacon times | Highest, due to constant listening mode |
Payload type | Small payloads, long intervals | Small payloads, long intervals, Periodic beacon from gateway | Small payloads |
Communication technique | Server communicates with end-device (downlink) during predetermined response windows | Server can initiate transmission at fixed intervals | End-device is constantly receiving |
Synchronization | No synchronization with network beacons | Synchronizes with network beacons for scheduled communication | No synchronization required, always ready for downlink |
Use Case | Suitable for low-power applications like sensors or metering | Suitable for applications needing predictable downlink response | Suitable for devices needing immediate response like actuators |
Typical Applications | Environmental monitoring, periodic sensors | Smart meters, applications needing predictable downlink slots | Real-time applications, lighting control, actuators |
Note: Information provided on this page is derived from LoRaWAN Specification V1.0 released on Jan.2015 by LoRa™ Alliance. Refer latest specifications published by LoRa Alliance ( https://www.lora-alliance.org ).
Conclusion
Class A devices prioritize minimal energy usage, making them ideal for battery-powered applications, while Class B and Class C offer more flexible scheduling options and lower latency. Class A is suited for low-power, periodic communication, while Class B and C provide more options for real-time communication and higher availability. A thorough understanding of these classes allows developers to design optimized IoT networks that maximize efficiency and meet application requirements effectively.