Understanding LoRaWAN Protocol Stack Layers

This stack is an essential part of the Low Power Wide Area Network (LPWAN) communication standard, enabling seamless and secure data transmission over long distances. Each layer in the LoRaWAN protocol stack plays a specific role in managing the network and ensuring efficient communication. From the radio frequency (RF) layer, physical layer, MAC layer to the application layer, understanding the functionalities and architecture of each layer is crucial for implementing and optimizing LoRaWAN based networks.

Introduction :
The terms LoRa stands for Long Range where as LoRaWAN stands for LoRa Wide Area Network. The technology has been designed to offer wide long range and low energy consumption. This wireless system uses different radio frequency bands for different regions such as 902 to 928 MHz band is used in US, 863-870 MHz/433-434 MHz in Europe and 470-510 MHz/779-787 MHz in China and so on.

LoRaWAN protocol stack

LoRa, LoRaWAN protocol stack

LoRaWAN consists of end devices, gateway and servers. There are two types of frame viz. uplink (from end device towards gateway/server) and downlink (from server/gateway towards end device).

LoRa message formats

The LoRaWAN protocol stack consists of following layers.
RF Layer: It takes care of radio frequency assignment and transmission of baseband information using RF carrier with the help of antenna over the air. The different frequency bands are allocated for different regions of the world.

Physical Layer: The layer lies above RF and it has many functions. It takes care of preamble , header formation, CRC for header and entire frame as shown in the figure-2. The raw data of the frame is later modulated using LoRa CSS/FSK or GFSK before necessary RF conversion for uplink transmission. Coverage, interference and optimization of RF issues are handled by physical layer.

MAC Layer: It takes care of MAC management messages between end device and server. Moreover MAC header, MIC and other MAC layer fields are used for specific purposes. MAC handles major fuctions such as energy consumption, security (AES128 Encryption) and mesh topology.

MAC layer takes care of different classes of end devices viz. class-A, Class-B and class-C.
➨Refer LoRaWAN MAC >> for complete information on MAC layer.
Class-A : Most energy efficient (Must be supported by all end nodes, DL after Tx
Class-B : Efficient with controlled DL (Slotted communication synchronized with beacon frames)
Class-C : Least Efficient (Devices listen continuously. DL without latency)
➨Refer LoRaWAN Classes >> for more information.

Application Layer: It is designed based on usage such as health care, smart city, smart farming, smart grid and so on.

Reference: LoRaWAN specifications published by LoRa Alliance ( https://www.lora-alliance.org ).

Conclusion

In conclusion, the LoRaWAN protocol stack layers form a cohesive framework that allows devices to communicate effectively in a wide range of environments. By comprehending the role of each layer, network designers and engineers can build robust, scalable and energy efficient IoT networks. This layered approach ensures flexibility and adaptability, making LoRaWAN a preferred choice for numerous LPWAN applications.

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