5.27.2.5.3 Reactive RAN feedback for Burst Arrival Time adaptation

If the RAN receives the capability for BAT adaptation without a Burst Arrival Time in the TSCAI and notification control is enabled for this QoS Flow, the 5GS will perform the following actions:

• If NG-RAN determines that the PDB of the QoS flow cannot be fulfilled in DL and UL direction, then if supported, NG-RAN shall determine a BAT offset value which reduces the time between the arrival of the traffic bursts and the time of the next possible transmission over the air interface for DL and UL, respectively. NG-RAN shall not provide a BAT offset with the same value until the PDB of the QoS Flow can be fulfilled again.

NOTE: NG-RAN determines BAT offset value in reference to the current arrival time of the bursts experienced by RAN in DL and by UE in UL. Further details on BAT offset determination for DL and UL are defined in TS 38.331 [28].

• The BAT offset is provided from NG-RAN to the SMF when sending the notification towards the SMF that the "GFBR can no longer be guaranteed" described in clause 5.7.2.4. The SMF provides the BAT offset to the PCF and the PCF provides the BAT offset to the AF as part of notifying the AF as described in clause 6.1.3.23a of TS 23.503 [45]