Gateway downlink after unconfirmed data uplink

I am working on a project based on the Arm Mbed LoRaWAN example, which uses unconfirmed uplinks. To my knowledge, unconfirmed uplinks should not be acknowledged by the receiver, as stated in Section in LoRaWAN L2 1.0.4 Specification.

I noticed in my backend (using ChirpStack) that once a message was sent, it receives an UnconfirmedDataDown. So my question is if the spec states that it shouldn’t be acknowledged, then why does my gateway (running LoRa Basics Station) respond to an UnconfirmedDataUp with an UnconfirmedDataDown?


There are MAC commands that can be initiated by the Network Server to control radio communications like a new ADR or frequency plan , this downlink is probably one of them. Maybe you can have more information on this downlink in Chripstack’s log