LoRaWAN Duty Cycle Specification & its application

Duty Cycle: It is the fraction of time a device is allowed to transmit on a given frequency channel within specific time period. It is expressed in units of percentage (%).

Example: 1% duty cycle refers to 36 seconds per hour of transmission on the assigned channel.

LoRaWAN uses unlicensed ISM bands which are shared among many devices. Devices limit their airtime based on duty cycle to prevent interference and congestion.

Duty cycle in LoRaWAN specifications

• For Europe as per ETSI, 1% is common in EU868 band. Across EU region, duty cycle can be between 0.1 to 10%.
• For North America & Australia, no restriction on duty cycle; but instead 400 ms dwell time is applied.
• For Asia pacific, some regions follow dwell time and some 1% duty cycle.

Significance of Duty Cycle in LoRaWAN

• It helps in achieving device transmission control. End devices must ensure transmissions do not exceed duty cycle limit. If it is exhausted, devices must wait before the next transmission.
• Above method of waiting may face limitations for applications requiring frequent uplinks. Due to this drawback, designers optimize payload size and use ADR technique of LoRaWAN to reduce airtime.

Conclusion: Duty cycle is used to define transmission airtime limit per hour per channel. It is very useful for capacity planning. network compliance and end device design.