Supposing I want the application firmware in my LoRaWAN end device to behave differently when it's in a given geolocation and that geolocation can be defined by the local Helium base station or cell ("gateway" in the LoRaWAN parlance?) that the end device is sitting in.
Suppose also that I'm happy to send one uplink and receive one downlink message in order to determine the gateway ID.
Section 3.2 of the LoRaWAN spec has only this to say about the downlink PHY frame:
Downlink PHY: Preamble PHDR PHDR_CRC PHYPayload
Is there also a gateway ID in there somewhere? Or is there in one of the other layers?
If not, could the application server know this from the uplink message and send it back as part of the downlink message payload?