What does the IAB-donor-CU do in step 1 of the IAB BH RLC channel establishment procedure?
Receives a UE CONTEXT MODIFICATION REQUEST message from the IAB-donor-DU
Sends a DL RRC MESSAGE TRANSFER message to the IAB-donor-DU
Sends a UE CONTEXT MODIFICATION REQUEST message to the IAB-donor-DU
Receives a DL RRC MESSAGE TRANSFER message from the IAB-donor-DU