4 Naf_EventExposure Service

29.5173GPP5G SystemApplication Function Event Exposure ServiceRelease 18Stage 3TS

Tools: ARFCN - Frequency Conversion for 5G NR/LTE/UMTS/GSM

4.1 Service Description

4.1.1 Overview

The Application Function Exposure Service, as defined in 3GPP TS 23.502 [3] and 3GPP TS 23.288 [4], is provided by the Application Function (AF). When the UE Application data is collected via the Data Collection AF, the Application Function Exposure Service, as defined in 3GPP TS 26.531 [28], 3GPP TS 26.501 [29], and 3GPP TS 26.512 [30], is provided by the Data Collection AF instantiated in 5GMS AF for the Event Consumer AF instantiated in 5GMS ASP.

This service:

– allows NF service consumers to subscribe, modify and unsubscribe for application events; and

– notifies NF service consumers with a corresponding subscription about observed events on the AF.

The types of observed events include:

AF application events exposed by AF:

– Service Experience information for an application;

– UE mobility information;

– UE communication information;

– Exceptions information;

– User Data Congestion information;

– Collective Behaviour information;

– Dispersion information; and

– Performance Data information;

UE application events exposed via Data Collection AF:

– Media Streaming QoE metrics;

– Media Streaming Consumption reports;

– Media Streaming Network Assistance invocation;

– Media Streaming Dynamic Policy invocation; and

– Media Streaming access activity.

When the event to which the NF service consumer has subscribed occurs, the AF reports the requested information to the NF service consumer based on the event reporting information definition requested by the NF service consumer (see 3GPP TS 23.502 [3]).

4.1.2 Service Architecture

The Data Analytics Architecture is defined in 3GPP TS 23.288 [4]. The Media Streaming UE application data collection via the Data Collection AF is defined in 3GPP TS 26.531 [28].

The Application Function Exposure Service (Naf_EventExposure) is part of the Naf service-based interface exhibited by the Application Function (AF).

The known NF service consumers of the Naf_EventExposure service are the Network Exposure Function (NEF) and the Network Data Analytics Function (NWDAF), or the Event Consumer AF in the 5GMS ASP.

The Naf_EventExposure service is provided by the AF and consumed by NF service consumers (e.g. NEF, NWDAF, Event Consumer AF), as shown in figure 4.1.2-1 for the SBI representation model and in figure 4.1.2-2 for reference point representation model.

Figure 4.1.2-1: Naf_EventExposure service Architecture, SBI representation

Figure 4.1.2-2: Naf_EventExposure service Architecture, reference point representation

4.1.3 Network Functions

4.1.3.1 Application Function (AF)

The AF is a functional element that provides service or application related information to NF service consumers.

The AF allows NF service consumers to subscribe to and unsubscribe from periodic notifications and/or notifications related to the detection of subscribed event.

4.1.3.2 NF Service Consumers

The Network Data Analytics Function (NWDAF):

– supports (un)subscribing to notifications of event(s) as described in clause 4.2.2.1;

– supports receiving the notifications of subscribed event(s) from the AF.

The Network Exposure Function (NEF):

– supports (un)subscribing to notifications of event(s) as described in clause 4.2.2.1;

– supports receiving the notifications of subscribed event(s) from the AF.

The Event Consumer Application Function (Event Consumer AF):

– supports (un)subscribing to notifications of event(s) as described in clause 4.2.2.1;

– supports receiving the notifications of subscribed event(s) from the Data Collection AF.

4.2 Service Operations

4.2.1 Introduction

Service operations defined for the Naf_EventExposure Service are shown in table 4.2.1-1.

Table 4.2.1-1: Naf_EventExposure Service Operations

Service Operation Name	Description	Initiated by
Naf_EventExposure_Subscribe	This service operation is used by an NF service consumer to subscribe to, or modify a subscription in the AF for event notifications on a specified application related event for one or more UE(s) or any UE.	NF Consumer (NWDAF, NEF, Event Consumer AF)
Naf_EventExposure_Unsubscribe	This service operation is used by an NF service consumer to unsubscribe from event notifications.	NF Consumer (NWDAF, NEF, Event Consumer AF)
Naf_EventExposure_Notify	This service operation is used by the AF to report application related event(s) to the NF service consumer which has subscribed to the event report service.	AF/Data Collection AF

4.2.2 Naf_EventExposure_Subscribe service operation

4.2.2.1 General

This service operation is used by an NF service consumer to subscribe for event notifications on specific event(s), or to modify an existing subscription.

The following are the types of events for which a subscription can be made by the NWDAF or NEF as the NF service consumer:

– Service Experience information for an application;

– UE mobility information;

– UE communication information;

– Exceptions information;

– User Data Congestion information;

– Collective Behaviour information;

– Dispersion information; and

– Performance Data information.

The following are the types of events for which a subscription can be made by the NWDAF, Event Consumer AF or NEF as the NF service consumer:

– Media Streaming QoE metrics.

The following are the types of events for which a subscription can be made by the Event Consumer AF or NEF as the NF service consumer:

– Media Streaming Consumption reports;

– Media Streaming Network Assistance invocation;

– Media Streaming Dynamic Policy invocation; and

– Media Streaming access activity.

The following procedures using the Naf_EventExposure_Subscribe service operation are supported:

– creating a new subscription;

– modifying an existing subscription.

4.2.2.2 Creating a new subscription

Figure 4.2.2.2-1 illustrates the creation of a subscription.

Figure 4.2.2.2-1: Creation of a subscription

To subscribe to event notifications, the NF service consumer shall send an HTTP POST request to the AF with: "{apiRoot}/naf-eventexposure/<apiVersion>/subscriptions" as request URI as shown in step 1 of figure 4.2.2.2-1, and the "AfEventExposureSubsc" data structure as request body.

The "AfEventExposureSubsc" data structure shall include:

– description of subscribed event information as "eventsSubs" attribute by using one or more "EventsSubs" data;

– description of the event reporting information as "eventsRepInfo" attribute;

– a URI where to receive the requested notifications as "notifUri" attribute;

– a Notification Correlation Identifier assigned by the NF service consumer for the requested notifications as "notifId" attribute.

The "AfEventExposureSubsc" data may include:

– a specific Authorization AS provisioned Data Access Profile Identifier as "dataAccProfId" attribute, if the feature "DataAccProfileId" is supported and the subscribed events including "MS_QOE_METRICS", "MS_CONSUMPTION", "MS_NET_ASSIST_INVOCATION", "MS_DYN_POLICY_INVOCATION", and/or "MS_ACCESS_ACTIVITY".

NOTE 1: The optional Data Access Profile Identifier provisioned by the Authorization AS procedures are specified in clause 5.8 of 3GPP TS 26.531 [28].

The "EventsSubs" data shall include:

– a event to subscribe as a "event" attribute; and

– event filter information as "eventFilter" attribute associated with the event.

The "eventsRepInfo" attribute may include:

– event notification method (periodic, one time, on event detection) as "notifMethod" attribute;

– Maximum Number of Reports as "maxReportNbr" attribute;

– Monitoring Duration as "monDur" attribute;

– repetition period for periodic reporting as "repPeriod" attribute;

– immediate reporting indication as "immRep" attribute;

– sampling ratio as "sampRatio" attribute;

– partitioning criteria for partitioning the UEs before performing sampling as "partitionCriteria" attribute if the EneNA feature is supported;

– group reporting guard time as "grpRepTime" attribute; and/or

– a notification flag as "notifFlag" attribute if the EneNA feature is supported.

The "eventFilter" shall include:

– identification of target UE(s) to which the subscription applies via :

1) identification of individual UE(s) via "gpsis" attribute or "supis" attribute; or

2) identification of group(s) of UE(s) via "exterGroupIds" attribute or "interGroupIds" attribute; or

3) identification of any UE via "anyUeInd" attribute.

NOTE 2: It is assumed that the AF is provisioned with the list of UE IDs (GPSIs or SUPIs) belonging to an External or Internal Group ID.

Depending on the event type:

– if the feature "ServiceExperience" is supported and the event is "SVC_EXPERIENCE", the "eventFilter" attribute may provide:

1) identification of application to which the subscription applies via "appIds" attribute;