5.37.4 Network Exposure of 5GS information

5GS and XR/media services cooperate to provide a better user experience using External Network Exposure.

Based on the AF request, the 5GS can expose the following information based on the QoS Monitoring as defined in clause 5.33.3 and/or clause 5.45:

• The UL and/or DL congestion information monitoring (see clause 5.45.3).

Based on the PCC rule from PCF, the SMF requests the NG-RAN to report congestion information (i.e. a percentage of congestion level for exposure) via GTP-U header to PSA UPF. This NG-RAN reported congestion information is sent to the PSA UPF in a common information element to support congestion information exposure and to support ECN marking for L4S in PSA UPF as described in clause 5.37.3.3. In the case of congestion information exposure, the PSA UPF interprets the RAN reported information as the percentage of congestion level for exposure and exposes the corresponding UL and/or DL congestion information via Nupf_EventExposure service or via SMF/PCF/NEF as described in clause 5.8.2.18. It can be applied to a Non-GBR or GBR QoS Flow. In the case of ECN marking for L4S in PSA UPF, the PSA UPF interprets the RAN reported information as percentage of packets that UPF uses for ECN marking for L4S as described in clause 5.37.3.3.

• The UL and/or DL Data rate information (see clause 5.45.4).

Based on the PCC rule from PCF, the SMF requests the PSA UPF to measure and report the information. They may be exposed to the AF directly by PSA UPF via Nupf_EventExposure service or via SMF/PCF/NEF as described in clause 5.8.2.18.

• The round trip delay for two service data flows considering the UL direction of a service data flow and the DL direction of another service data flow in the same PDU Session.

It is determined based on the QoS Monitoring for packet delay of individual QoS Flows as described in clause 5.33.3. The PCF derives the separate QoS monitoring policies for each direction packet delay (see clause 5.33.3) based on AF request and local policy. The PCF provides the two QoS Monitoring policies in the PCC rules for the service data flows. The PSA UPF reports the delay information per QoS Flow to the SMF. The SMF reports to PCF. The PCF derives round trip delay information based on the two direction's packet delay result for the service data flows and exposes the information to the AF directly or via NEF.

• The round trip delay for one service data flow.

If the service data flow is mapped to two QoS Flows (i.e. the UL traffic and DL traffic of the service data flow are separated into two QoS flows respectively) in the same PDU Session, similarly to the round trip delay for two service data flows over two QoS flows, the PCF triggers QoS Monitoring for each direction packet delay of individual QoS flows respectively and derives round trip delay based on the two direction QoS flows' packet delay monitored result.

NOTE: How PCF calculates the requested round trip delay for multiple QoS Flows from delays of individual QoS Flows is not specified in this specification.

• The UL and/or DL available bitrate for a GBR QoS Flow (see clause 5.45.6).

For a GBR QoS Flow, based on the PCC rule from PCF, the SMF requests the NG-RAN to report the UL and/or DL available bitrate. The NG-RAN reports the UL and/or DL available bitrate information to the PSA UPF via the GTP-U header of UL packets.

The SMF further requests the PSA UPF to expose the available bitrate to the AF directly or via local NEF, as described in clause 5.8.2.18.

The AF may provide the Alternative QoS parameter set requirements and Averaging Window to the NEF/PCF for the GBR QoS Flow as specified in clause 4.15.6.6 of TS 23.502 [3].

Upon AF request, 5GS may expose the UL and DL data rate limitation information for a Non-GBR service data flow or a PDU Session to the AF. The data rate limitation information is defined as the maximum data rate that can be achieved for the service data flow or the PDU Session, respectively and is determined by the PCF as described in clause 6.1.3.27.1 of TS 23.503 [45]:

• For a new or an ongoing service data flow bound to an AF session, the as data rate limitation information for a Non-GBR service data flow is exposed by means of the AF session with QoS procedure (as defined in clause 4.15.6.6 and clause 4.15.6.6a of TS 23.502 [3]).
• When the AF subscribes to event notifications for a PDU Session, the data rate limitation information for a PDU Session is exposed by means of the Npcf_EventExposure service (as defined in clause 5.2.5.7 of TS 23.502 [3]).