5.7.1.10 UE-Slice-MBR enforcement and rate limitation

If a supporting NG-RAN receives for a UE a UE-Slice-MBR (see clause 5.7.2.6) for an S-NSSAI from the AMF, the NG-RAN shall apply this UE-Slice-MBR for all PDU Sessions of that UE corresponding to the S-NSSAI which have an active user plane if feasible. In particular, the NG-RAN shall enforce this UE-Slice-MBR as follows:

• Whenever a request for a GBR QoS Flow establishment or modification is received, the NG-RAN admission control shall ensure that the sum of the GFBR values of the admitted GBR QoS Flows is not exceeding the UE-Slice-MBR and, if the QoS Flow cannot be admitted, the NG-RAN shall reject the establishment/modification of the QoS Flow.

NOTE: If the UE-Slice-MBR would be exceeded by a new/modified GBR QoS Flow, the NG-RAN determines whether the new/modified GBR QoS Flow can pre-empt any existing GBR QoS Flow of the UE's PDU Session(s) corresponding to the same S-NSSAI based on their ARP values (as per clause 5.7.2.2), e.g. to support certain priority services (e.g. MPS). If this is not possible, the NG-RAN can reject the establishment/modification of the QoS Flow.

• The NG-RAN shall ensure that the aggregated bitrate across all GBR and Non-GBR QoS Flows belonging to those PDU Sessions is not exceeding the UE-Slice-MBR, while always guaranteeing the GFBR of every GBR QoS Flow of those PDU Sessions as described in clause 5.7.2.5.