Method and LoRaWAN system for transmitting downlink broadcast messages to multiple end devices in a LoRaWAN network

Low-Power LoRaWAN Broadcast Transmission Using Downlink Initiators and RX2 Windows

This technology is a method and system for LoRaWAN where one end device is designated as a downlink initiator to periodically send downlink requests, allowing the network server to broadcast messages to multiple end devices simultaneously using the second receive window (RX2) of the Class A slot timing.

While LoRa is a power-efficient, long-range IoT communication technology, Class A devices only open short receive windows immediately after an uplink, making it difficult for servers to send downlinks to multiple devices at will. Processing individual downlinks for each device also significantly increases network traffic and server data storage burdens.

This technology distributes power consumption by rotating the initiator role to the device with the lowest communication frequency when the sum of its uplink and downlink counts exceeds a dynamically adjusted threshold. It allows broadcasting to specific groups based on sensor type or region. Applicable to smart metering, smart city sensor networks, and remote batch control, it enables simultaneous distribution of commands and settings to multiple devices while maintaining Class A power efficiency.

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Key Features:

• A step where one of multiple end devices acts as a downlink initiator, periodically sending downlink requests to the network server via a gateway
• A step where the network server transmits broadcast messages using the second receive window of the LoRa protocol Class A end device slot timing
• A configuration that sets an end device as the downlink initiator upon its initial join request and approval by the network server
• A configuration that replaces the initiator with the end device having the lowest sum of uplink and downlink counts when that sum exceeds a threshold that grows dynamically based on the number of changes

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This invention was developed with research support from the National Research Foundation of Korea for a real-time condensation detection and prediction system considering user residential behavior patterns.

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