ConstReadonlyRx1: LorawanReceiveWindowThe first window, on the uplink's downlink channel.
ReadonlyRx2: LorawanReceiveWindowThe second, on the fixed frequency and data rate.
ReadonlyRxr: LorawanReceiveWindowThe relay window, which a device under a relay opens last, TS011-1.0.1 chapter 7.
Which receive window a frame arrived in.