This guide contains implementation details primarily for gateway manufacturers intending to implement the LoRa Basics™ Station protocol.
Use of DevEui field in Downlink Messages
Gateways using the LoRa Basics™ Station
protocol report the successful transmission of downlink messages via the Transmit Confirmation (
dntxed) message. In order to correlate the confirmation message to a downlink, the LoRa Basics™ Station
protocol provides two options to the LNS. The LNS is offered the flexibility to implement either of these mechanisms.
a. Using the
DevEui and the
- In this mode, the LNS uses a per-device downlink counter. Gateways echo the
diidfields sent on the downlink message on the corresponding Transmit Confirmation message.
- The LNS then forwards the transmit confirmation upstream.
- This is useful for debugging using LoRa Basics™ Station
gateway logs since the
DevEuiwill be printed. However, this exposes the DevEui of end devices to gateways which is not desirable in cases where the gateway is not owned/operated by the device owner.
- The Things Stack does not use this method to correlate Transmit Confirmations.
b. Using only the
- The LNS can choose to make the
diidfield globally unique per gateway (per session). The LNS can then maintain a correlation of the
diidvalues to downlink messages.
- When the gateway sends a Transmit Confirmation message, the LNS can then use the echoed
diidvalue to look up the downlink message and retrieve information on the end device and forward the transmit confirmation upstream.
- In this mode, the
DevEuifield of the downlink message is not used by the LNS but should be set to a non-zero value.
- This is the approach used by The Things Stack, where the
DevEuiis set to
0000000000000001for all downlink messages.