Content for  TS 23.288  Word version:  18.3.0

This clause specifies how NWDAF can provide Observed Service Experience (i.e. average of observed Service MoS and/or variance of observed Service MoS indicating service MOS distribution for services such as audio-visual streaming as well as services that are not audio-visual streaming such as V2X and Web Browsing services) analytics, in the form of statistics or predictions, to a service consumer. The Observed Service Experience analytics may provide one or more of the following outputs:

• Service Experience for a Network Slice: Service Experience for a UE or a group of UEs or any UE in a Network Slice;
• Service Experience for an Application: Service Experience for a UE or a group of UEs or any UE in an Application or a set of Applications;
• Service Experience for an Edge Application over a UP path: Service experience for a UE or a group UEs or any UE in an Application or a set of Applications over a specific UP path (UPF, DNAI and EC server);
• Service Experience for an Application over a RAT Type or Frequency or both: Service experience for a UE or a group of UEs in an Application or a set of Applications over a RAT Type or over a Frequency or both as defined in Table 6.4.1-1.
• Service Experience for an Application transferring data over a PDU Session: Service experience for a UE or a group of UEs or any UEs in an Application or a set of Applications transferring data over a PDU Session with PDU Session parameters i.e. S-NSSAI, DNN, PDU Session Type , SSC mode and optionally an Access Type or with combination of PDU Session parameters such as a list of the tuple (PDU Session Type, SSC mode) optionally per Access Type.

Therefore, Observed Service experience may be provided as defined in clause 6.4.3. For example, individually per UE or group of UEs, or globally, averaged per Application or averaged across a set of Applications on a Network Slice. The service consumer may be an NF (e.g. PCF, NSSF, AMF, NEF), AF, or the OAM. The consumer of these analytics shall indicate in the request or subscription:

• Analytics ID = "Service Experience";
• Target of Analytics Reporting: one or more SUPI(s) or Internal Group Identifier(s), or "any UE";
• Analytics Filter Information as defined in Table 6.4.1-1 and optionally a list of analytics subsets that are requested (see clause 6.4.3);
• optionally, maximum number of objects and maximum number of SUPIs;
• optionally, preferred level of accuracy of the analytics;
• optionally, preferred level of accuracy per analytics subset;
• optionally, preferred order of results for the list of Application Service Experiences and/or Slice instance service experiences: "ascending" or "descending";
• optionally, preferred granularity of location information: TA level or cell level or "below cell level";
• Analytics target period that indicates the time window for which the statistics or predictions are requested;
• in a subscription, the Notification Correlation Id and the Notification Target Address; and
• optionally, Reporting Thresholds, which apply only for subscriptions and indicate conditions on the Service Experience to be reached in order to be notified by the NWDAF (see Table 6.4.3-1 and Table 6.4.3-2).

The NWDAF shall notify the result of the analytics to the consumer as specified in clause 6.4.3. NWDAF collects the network data from AF (directly or via NEF) and from other 5GC NF(s) in order to calculate and provide statistics and predictions on the observed service experience to a consumer NF or to OAM. When the AF provides Service Experience Information and the Target of Analytics Reporting is one or more UE ID(s), the AF may also provide a Service Experience Contribution Weight with each UE's Service Experience value. The Service Experience Contribution Weight is determined by the AF and indicates the relative importance of each UE's Service Experience. The NWDAF may use the Service Experience Contribution Weight(s) to calculate and provide statistics, confidence values and predictions on the observed service experience to a consumer NF or to OAM. Based on the Analytics Filter information in Table 6.4.1-1 and the Target of Analytics Reporting provided by the service consumer in the analytics subscription or request, NWDAF determines whether service experience analytics should be delivered for:

1. Application(s);
2. Network Slice;
3. both Application(s) and Network Slice;
4. Edge Applications over a UP path;
5. Application(s) over RAT Type(s) and/or Frequency value(s);
6. Application(s) running over a PDU Session using the following PDU Session parameters or combination of them, i.e. S-NSSAI, DNN, PDU Session type, SSC Mode and optionally per Access Type.

If NWDAF is unable to differentiate based on the analytics subscription or request, it provides service experience analytics for both Application(s) and Network Slice. If service experience for both Application(s) and Network Slice is desired but the Target of Analytics Reporting or Analytics Filter information values (e.g. Area of Interest) need to be different, separate subscriptions/requests may be provided by the service consumer.

The service data and performance data collected from the AF (including the service data collected from the UE through the AF), the network data from other 5GC NFs and the network data from OAM and MDAS/MDAF for observed service experience are defined in Table 6.4.2-1, Table 6.4.2-1a, Table 6.4.2-2, Table 6.4.2-3, Table 6.4.2-4 and Table 6.4.2-5 respectively.

NWDAF subscribes to the service data from AF in the Table 6.4.2-1 either directly for trusted AFs by invoking Naf_EventExposure_Subscribe service (Event ID = Service Experience information, Event Filter information = Area of Interest, Application ID) as defined in TS 23.502, or indirectly for untrusted AFs via NEF by invoking Nnef_EventExposure_Subscribe service (Event ID = Service Experience information, Event Filter information = Area of Interest, Application ID) where NEF translates the Area of Interest into geographic zone identifier(s). For the information whose source is UE (via AF), the AF collects data from the UE as defined in clause 6.2.8.

NWDAF subscribes to the performance data from AF in the Table 6.4.2-1a either directly for trusted AFs by invoking Naf_EventExposure_Subscribe service (Event ID = Performance Data, Event Filter information = Area of Interest, Application ID) as defined in TS 23.502, or indirectly for untrusted AFs via NEF by invoking Nnef_EventExposure_Subscribe service (Event ID = Performance Data, Event Filter information = Area of Interest, Application ID) where NEF translates the Area of Interest into geographic zone identifier(s).

NWDAF subscribes to the network data from 5GC NF(s) in the Table 6.4.2-2 by invoking Nnf_EventExposure_Subscribe service operation with the following Event IDs as input parameters:

• AMF Source: Namf_EventExposure_Subscribe (Event IDs = Location Changes, Area of Interest).
• SMF Source: Nsmf_EventExposure_Subscribe (Event ID = QFI allocation).

The Event Filters for the service data collection from SMF, AMF and AF are defined in TS 23.502. The timestamps are provided by each NF to allow correlation of QoS and traffic KPIs. The clock reference is able to know the accuracy of the time and correlate the time series of the data retrieved from each NF. The NWDAF collects the following MDAF analysis result listed in Table 6.4.2-5, as defined in clauses 8.4.2.1.3 and 8.4.4.3 of TS 28.104.

The NWDAF services as defined in the clause 7.2 and clause 7.3 are used to expose the analytics.

• Service Experience statistics information is defined in Table 6.4.3-1.
• Service Experience predictions information is defined in Table 6.4.3-2.

The number of Service Experiences and SUPIs are limited respectively by the maximum number of objects and the Maximum number of SUPIs provided as part of Analytics Reporting Information by the NWDAF Service Consumer.

This procedure allows the consumer to request Analytics ID "Service Experience" for a particular Application. The consumer includes both the Application ID for which the Service Experience is requested and indicates that the Target of Analytics Reporting is "any UE". If the Target for Analytics Reporting is either a SUPI or an Internal-Group-Id the procedure in clause 6.4.6 applies. At the same time, for an Application ID, a set of initial QoS parameter combinations per service experience window (e.g. one is for 3<Service MOS<4 and another is for 4<Service MOS<5) is defined in PCF (e.g. by configuration of operator policies) that may be updated based on the Service Experience reported by NWDAF. If the consumer NF is a PCF and it determines that the application SLA is not satisfied, it may take into account the Observed Service Experience and the operator policies including SLA and required Service Experience (which can be a range of values) to determine new QoS parameters to be applied for the service, as defined in clause 6.1.1.3 and clause 6.2.1.2 of TS 23.503. If the consumer NF is an AF (e.g. MEC or other Application Server), it may use the Observed Service Experience related network data analytics to determine whether the user experience can be satisfied. If not, the AF may determine to adjust service parameters, e.g. for a video service this may be bit rate, frame rate, codec format, compression parameter, screen size, etc. to better match the network conditions and achieve better user experience. If the consumer NF is SMF, PCF or AF/Application Server, it may take into account the Observed Service Experience analytics per UP path (i.e. UPF and/or DNAI and/or AS instance address as defined in Table 6.4.3-1) to perform the following procedures:

• The consumer SMF determines to (re)selects UP paths, including UPF and DNAI, as described in clause 4.3.5 of TS 23.502. In addition, the SMF may (re)configure traffic steering, updating the UPF regarding the target DNAI with new traffic steering rules.
• The consumer AF/Application Server determines to adjust service parameters, e.g. service parameters of video for adjustment may be bit rate, frame rate, codec format, compression parameter, screen size, etc. or service parameters for the AI/ML operations described in clause 6.40 of TS 22.261. In addition, the AF/ Application Server may provide an updated list of DNAI(s) for SMF to perform relocation when appropriate.
• The consumer PCF may provide an updated list of DNAI(s) for SMF to perform relocation upon AF request.

If the consumer NF is a NEF, it may take into account the Observed Service Experience analytics to support Member UE selection as detailed in clause 4.15.13 of TS 23.502.

This procedure is similar to the procedure in clause 6.4.4, with the following differences. The consumer needs to request the Analytics ID "Service Experience" for all UEs or a group of UEs or a UE on a Network Slice, identified by an S-NSSAI. If multiple Network Slice instances of the same Network Slice are deployed, associated NSI ID(s) may be used in addition to S-NSSAI. If 'any UE' is the Target of Analytics Reporting, NWDAF may subscribe to UE mobility event notifications of AMF as described in clause 5.3.4.4 of TS 23.501 using event ID "UE moving in or out of Area of Interest" and Event Filters as described in Table 5.2.2.3.1-1 of TS 23.502 if it is needed to retrieve the list of SUPIs (and GPSIs if available) in the area of interest. The event exposure service request may also include the immediate reporting flag as Event Reporting Information as described in Table 4.15.1-1 of TS 23.502. In addition, service experience data may need to be collected from multiple Applications. If each Application is hosted in different AFs, NWDAF subscribes the service data in the Table 6.4.2-1 from the different AFs by invoking Nnef_EventExposure_Subscribe or Naf_EventExposure_Subscribe services for each Application (Event ID = Service Experience information, Event Filter information, Application ID) as defined in TS 23.502. Figure 6.4.5-1 shows an example procedure with two AFs. If one AF provides the service experience data of multiple Applications, the set of Application IDs is provided by NWDAF to the AF with the Naf_EventExposure_Subscribe service operation, as defined TS 23.502. The Observed Service Experience for a Network Slice when consumed by OAM could be used as described in Annex H of TS 28.550.

Figure 6.4.6-1 depicts procedure for NWDAF providing Service Experience for an application for a UE or a group of UEs.

The procedure in clause 6.4.4 applies with the following additions. The consumer needs to request the Analytics ID "Service Experience" for a UE identified by a SUPI or a group of UEs identified by an Internal Group-Id. The consumer includes both the Application ID for which their Service Experience is requested and the Target of Analytics Reporting for a SUPI or an Internal-Group-Id. Analytic Filter Information can be set according to clause 6.4.1. The NWDAF may collect UE location information from the GLMC if the consumer requested fine granularity location information according to clause 6.4.2.1. When NEF is the NF service consumer, the NEF translates a GPSI into a SUPI or an External-Group-Id into an Internal-Group-Id then includes it in the Target of Analytics Reporting.