4 Services offered by the NEF

29.5913GPP5G SystemNetwork Exposure Function Southbound ServicesRelease 17Stage 3TS

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

4.1 Introduction

The NEF offers to other NFs the following southbound services:

– Nnef_EventExposure

– Nnef_PFDManagement

– Nnef_SMContext

– Nnef_Authentication

– Nnef_EASDeployment

NOTE 1: The northbound services offered by the NEF are defined in 3GPP TS 29.522 [15], e.g. the northbound requirement of Nnef_EventExposure service or Nnef_EASDeployment.

NOTE 2: The services offered by the NEF (e.g. Nnef_EventExposure service) as specified in the present specification are only applicable for Nnef southbound services.

NOTE 3: The Nnef_PFDManagement service offered by the NEF southbound is defined in 3GPP TS 29.551 [19].

NOTE 4: The Nnef_SMContext service offered by the NEF southbound is defined in 3GPP TS 29.541 [20].

NOTE 5: The Nnef_Authentication service offered by the NEF southbound is defined in 3GPP TS 29.256 [23].

4.2 Nnef_EventExposure Service

4.2.1 Service Description

4.2.1.1 Overview

The Nnef_EventExposure service, as defined in 3GPP TS 23.502 [3], is provided by the Network Exposure Function (NEF). When the UE Application data is collected via the Data Collection AF, the NEF collect the Application Function Exposure Service as defined in 3GPP TS 26.531 [24], 3GPP TS 26.501 [25], and 3GPP TS 26.512 [26], 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 NEF.

The types of observed events applicable for NEF include:

AF application events exposed by AF:

– Service experience;

– UE mobility;

– UE communication;

– Exceptions;

– User Data Congestion;

– Dispersion;

– Performance Data information; and

– Collective Behaviour 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.

The target of the event reporting may include one or more UE(s), a group of UEs or any UE (i.e. all UEs). When an event to which the NF service consumer has subscribed occurs, the NEF reports the requested information to the NF service consumer based on the event reporting information definition requested by the NF service consumer.

4.2.1.2 Service Architecture

The 5G System Architecture is defined in 3GPP TS 23.501 [2]. The Network Data Analytics Exposure architecture is defined in 3GPP TS 23.288 [14]. The Media Streaming UE application data collection via the Data Collection AF is defined in 3GPP TS 26.531 [24].

The Nnef_EventExposure service is part of the Nnef service-based interface exhibited by the Network Exposure Function (NEF).

Known consumers of the Nnef_EventExposure service are:

– Network Data Analytics Function (NWDAF)

– Event Consumer AF in the 5GMS ASP

The Nnef_EventExposure service is provided by the NEF and consumed by NF service consumers (e.g. NWDAF, Event Consumer AF), as shown in figure 4.2.1.2-1 for the SBI representation model and in figure 4.2.1.2-2 for reference point representation model.

Figure 4.2.1.2-1: Reference Architecture for the Nnef_EventExposure Service; SBI representation

Figure 4.2.1.2-2: Reference Architecture for the Nnef_EventExposure Service: reference point representation

4.2.1.3 Network Functions

4.2.1.3.1 Network Exposure Function (NEF)

The Network Exposure Function (NEF) is a functional element that provides application or user related information to the NF service consumers as defined in this specification.

The NEF allows the NF consumer(s) to (un)subscribe to notifications of monitoring observed event, and sends the notification to the NF consumer(s) when a subscribed event is detected.

4.2.1.3.2 NF Service Consumers

The known NF service consumers are as follows:

The Network Data Analytics Function (NWDAF):

– supports (un)subscribing to notifications of subscribed event(s) from the NEF;

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

The Event Consumer Application Function (Event Consumer AF):

– supports (un)subscribing to notifications of service experience information from the NEF;

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

4.2.2 Service Operations

4.2.2.1 Introduction

Service operations defined for the Nnef_EventExposure Service are shown in table 4.2.2.1-1.

Table 4.2.2.1-1: Nnef_EventExposure Service Operations

Service Operation Name	Description	Initiated by
Nnef_EventExposure_Subscribe	This service operation is used by an NF service consumer to subscribe to, or modify a subscription in the NEF for event notifications on a specified application or user related event.	NF service consumer
Nnef_EventExposure_Unsubscribe	This service operation is used by an NF service consumer to unsubscribe from event notifications.	NF service consumer
Nnef_EventExposure_Notify	This service operation is used by the NEF to report application or user related event(s) to the NF service consumer which has subscribed to the event report service.	NEF

4.2.2.2 Nnef_EventExposure_Subscribe service operation

4.2.2.2.1 General

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

The following are the types of events for which a subscription to notifications can be created by the NWDAF as the NF service consumer:

– Service experience;

– UE mobility;

– UE communication;

– Exceptions;

– User Data Congestion;

– Dispersion;

– Performance Data information; and

– Collective Behaviour information.

The following are the types of events for which a subscription can be made by the NWDAF or Event Consumer AF 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 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 Nnef_EventExposure_Subscribe service operation are supported:

– creating a new subscription;

– modifying an existing subscription.

4.2.2.2.2 Creating a new subscription

Figure 4.2.2.2.2-1 illustrates the creation of a Network Exposure Event Subscription.

Figure 4.2.2.2.2-1: Creation of a subscription

To subscribe to event notifications, the NF service consumer shall send an HTTP POST request to the NEF with: "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions" as request URI as shown in step 1 of figure 4.2.2.2.2-1, and the "NefEventExposureSubsc" data structure as request body.

The "NefEventExposureSubsc" data structure shall include:

– 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; and

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

The "NefEventExposureSubsc" data structure may also include:

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

– 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: 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 "NefEventSubs" data structure shall include:

– an event to subscribe to 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.

If the NEF cannot successfully fulfil the received HTTP POST request due to an internal error or an error in the HTTP POST request, the NEF shall send an HTTP error response as specified in clause 5.1.7.

Upon successful reception of an HTTP POST request with "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions" as request URI and "NefEventExposureSubsc" data structure as request body, the NEF shall create a new "Individual Network Exposure Event Subscription" resource, store the subscription and send an HTTP "201 Created" response, as shown in step 2 of figure 4.2.2.2.2-1. The NEF shall include in the "201 Created" response:

– a Location header field; and

– an "NefEventExposureSubsc" data type in the payload body.

The Location header field shall contain the URI of the created individual application session context resource i.e. "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions/{subscriptionId}".

The "NefEventExposureSubsc" data type payload body shall contain the representation of the created "Individual Network Exposure Event Subscription".

When the "monDur" attribute is included in the response by the NEF, it represents NEF selected expiry time that is equal or less than the expiry time received in the request.

When the "immRep" attribute is included and set to "true" in the subscription and the subscribed events are available, the NEF shall include the reports of the events subscribed, if available, in the HTTP POST response.

When the sampling ratio attribute, as "sampRatio", is included in the subscription without a "partitionCriteria" attribute, the NEF shall select a random subset of UEs among the target UEs according to the sampling ratio and only report the event(s) related to the selected subset of UEs. If the "partitionCriteria" attribute is additionally included, then the NEF shall first partition the UEs according to the value of the "partitionCriteria" attribute and then select a random subset of UEs from each partition according to the sampling ratio and only report the event(s) related to the selected subsets of UEs.

When the group reporting guard time, as "grpRepTime" attribute, is included in the subscription, the NEF shall accumulate all the event reports for the target UEs until the group reporting guard time expires. Then, the NEF shall notify the NF service consumer using the Nnef_EventExposure_Notify service operation, as described in clause 4.2.2.4.

When the "notifFlag" attribute is included and set to "DEACTIVATE" in the request, the NEF shall mute the event notification and store the available events.

4.2.2.2.3 Modifying an existing subscription

Figure 4.2.2.2.3-1 illustrates the modification of an existing subscription.

Figure 4.2.2.2.3-1: Modification of an existing subscription

To modify an existing subscription to event notifications, the NF service consumer shall send an HTTP PUT request with: "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions/{subscriptionId}" as request URI, as shown in step 1 of figure 4.2.2.2.3-1, where "{subscriptionId}" is the subscription correlation ID of the existing subscription. The "NefEventExposureSubsc" data structure is included as request body as described in clause 4.2.2.2.2.

NOTE 1: An alternate NF service consumer than the one that requested the generation of the subscription resource can send the PUT request.

NOTE 2: The "notifUri" attribute within the NefEventExposureSubsc data structure can be modified to request that subsequent notifications are sent to a new NF service consumer.

NOTE 3: The "monDur" attribute within the NefEventExposureSubsc data structure can be modified to extend the expiry time to keep receiving notifications.

If the NEF cannot successfully fulfil the received HTTP PUT request due to an internal error or an error in the HTTP PUT request, the NEF shall send an HTTP error response as specified in clause 5.1.7.

If the feature "ES3XX" is supported, and the NEF determines the received HTTP PUT request needs to be redirected, the NEF shall send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [4].

Upon successful reception of an HTTP PUT request with: "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions/{subscriptionId}" as request URI and "NefEventExposureSubsc" data structure as request body, the NEF shall update the subscription and send an HTTP "200 OK" response with the "NefEventExposureSubsc" data structure as response body containing the representation of the modified "Individual Network Exposure Event Subscription", or an HTTP "204 No Content" response, as shown in step 2 of figure 4.2.2.2.3-1.

When the "monDur" attribute is included in the response by the NEF, it represents NEF selected expiry time that is equal or less than the expiry time received in the request.

When the "immRep" attribute is included and sets to "true" in the subscription and the subscribed events are available, the NEF shall include the reports of the events subscribed, if available, in the HTTP PUT response.

When the sampling ratio, as "sampRatio" attribute, is included in the subscription without a "partitionCriteria" attribute, the NEF shall select a random subset of UEs among the target UEs according to the sampling ratio and only report the event(s) related to the selected subset of UEs. If the "partitionCriteria" attribute is additionally included, then the NEF shall first partition the UEs according to the value of the "partitionCriteria" attribute and then select a random subset of UEs from each partition according to the sampling ratio and only report the event(s) related to the selected subsets of UEs.

When the "notifFlag" attribute is included, and set to "DEACTIVATE" in the request, the NEF shall mute the event notification and store the available events; if it is set to "RETRIEVAL" in the request, the NEF shall send the stored events to the NF service consumer, and mute the event notification again and store available events; if it is set to "ACTIVATE" and the event notifications are muted (due to a previously received "DECATIVATE" value), the NEF shall unmute the event notification, i.e. start sending again notifications for available events.

4.2.2.3 Nnef_EventExposure_Unsubscribe service operation

4.2.2.3.1 General

This service operation is used by an NF service consumer to unsubscribe from event notifications.

The following procedure using the Nnef_EventExposure_Unsubscribe service operation is supported:

– unsubscription from event notifications.

4.2.2.3.2 Unsubscription from event notifications

Figure 4.2.2.3.2-1 illustrates the unsubscription from event notifications.

Figure 4.2.2.3.2-1: Unsubscription from event notifications

To unsubscribe from event notifications, the NF service consumer shall send an HTTP DELETE request with "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions/{subscriptionId}" as request URI, as shown in step 1 of figure 4.2.2.3.2-1, where "{subscriptionId}" is the subscription correlation identifier of the existing subscription resource that is to be deleted.

If the NEF cannot successfully fulfil the received HTTP DELETE request due to an internal error or an error in the HTTP DELETE request, the NEF shall send an HTTP error response as specified in clause 5.1.7.

If the feature "ES3XX" is supported, and the NEF determines the received HTTP DELETE request needs to be redirected, the NEF shall send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [4].

Upon successful reception of an HTTP DELETE request with: "{apiRoot}/nnef-eventexposure/<apiVersion>/subscriptions/{subscriptionId}" as request URI, the NEF shall remove the corresponding subscription and send an HTTP "204 No Content" response, as shown in step 2 of figure 4.2.2.3.2-1.

4.2.2.4 Nnef_EventExposure_Notify service operation

4.2.2.4.1 General

The Nnef_EventExposure_Notify service operation enables the NEF to notify the NF service consumer(s) that the previously subscribed application related event occurred.

The following procedure using the Nnef_EventExposure_Notify service operation is supported:

– notification about subscribed events.

4.2.2.4.2 Notification about subscribed events

Figure 4.2.2.4.2-1 illustrates the notification about subscribed events.

Figure 4.2.2.4.2-1: Notification about subscribed events

If the NEF observes application related event(s) for which an NF service consumer has subscribed, the NEF shall send an HTTP POST request as shown in step 1 of figure 4.2.2.4.2-1, with the "{notifUri}" as request URI containing the value previously provided by the NF service consumer within the corresponding subscription, and the "NefEventExposureNotif" data structure.

The "NefEventExposureNotif" data structure shall include:

– notification correlation ID provided by the NF service consumer during the subscription as "notifId" attribute; and

– information about the observed event(s) within the "eventNotifs" attribute that shall contain for each observed event an "NefEventNotification" data structure that shall include:

– the application related event as "event" attribute;

– the time at which the event was observed encoded as "timeStamp" attribute;

– if the "event" attribute is "SVC_EXPERIENCE", service experience information about the application involved in the reported event in the "svcExprcInfos" attribute;

– if the "event" attribute is "UE_MOBILITY", UE mobility information assoicated with the application as "ueMobilityInfos" attribute;

– if the "event" attribute is "UE_COMM", UE communication information assoicated with the application as "ueCommInfos" attribute;

– if the "event" attribute is "EXCEPTIONS", exceptions information associated with a service flow as "excepInfos" attribute;

– if the "event" attribute is "PERF_DATA", Performance Data Analytics related information as "perfDataInfos" attribute;

– if the "event" attribute is "COLLECTIVE_BEHAVIOUR", collective behaviour information associated with the UEs and its applications as "collBhvrInfs" attribute;

– if the "event" attribute is "USER_DATA_CONGESTION", user data congestion information collected for an AF application as "congestionInfos" attribute; and

– if the "event" attribute is "DISPERSION", UE dispersion information collected for an AF as "dispersionInfos" attribute.

– if the "event" attribute is "MS_QOE_METRICS", Media Streaming QoE metrics information collected for an UE application via the Data Collection AF as "msQoeMetrInfos" attribute.

– if the "event" attribute is "MS_CONSUMPTION", Media Streaming Consumption reports information collected for an UE application via the Data Collection AF as "msConsumpInfos" attribute.

– if the "event" attribute is "MS_NET_ASSIST_INVOCATION", Media Streaming Network Assistance invocation information collected for an UE application via the Data Collection AF as "msNetAssInvInfos" attribute.

– if the "event" attribute is "MS_DYN_POLICY_INVOCATION", Media Streaming Dynamic Policy invocations information collected for an UE application via the Data Collection AF as "msDynPlyInvInfos" attribute.

– if the "event" attribute is "MS_ACCESS_ACTIVITY", Media Streaming access activity information collected for an UE application via the Data Collection AF as "msAccActInfos" attribute.

If the NF service consumer cannot successfully fulfil the received HTTP POST request due to an internal error or an error in the HTTP POST request, the NF service consumer shall send an HTTP error response as specified in clause 5.1.7.

If the feature "ES3XX" is supported, and the NF service consumer determines the received HTTP POST request needs to be redirected, the NF service consumer shall send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [4].

Upon successful reception of an HTTP POST request with "{notifUri}" as request URI and "NefEventExposureNotif" data structure as request body, the NF service consumer shall send an HTTP "204 No Content" response, as shown in step 2 of figure 4.2.2.4.2-1, in case of a successful processing.

4.3 Nnef_EASDeployment Service

4.3.1 Service Description

4.3.1.1 Overview

The Nnef_EASDeployment service, as defined in 3GPP TS 23.502 [3], is provided by the Network Exposure Function (NEF). This service allows the SMF to subscribe/unsubscribe the notification of AF provisioned EAS Deployment information, and for the NEF to notify the AF provisioned EAS Deployment information to the subscribed SMF.

4.3.1.2 Service Architecture

The 5G System Architecture is defined in 3GPP TS 23.501 [2].

The Nnef_EASDeployment service is part of the Nnef service-based interface exhibited by the Network Exposure Function (NEF).

Known consumer of the Nnef_EASDeployment service is:

– Session Management Function (SMF)

Figure 4.3.1.2-1: Reference Architecture for the Nnef_EASDeployment Service; SBI representation

Figure 4.3.1.2-2: Reference Architecture for the Nnef_EASDeployment Service: reference point representation

4.3.1.3 Network Functions

4.3.1.3.1 Network Exposure Function (NEF)

The Network Exposure Function (NEF) is a functional element that support for the NF service consumer (i.e SMF) subscribing to the notification of the AF provisioned EAS Deployment Information and provide EAS Deployment Information change notification to the NF service consumer as defined in this specification.

4.3.1.3.2 NF Service Consumers

The known NF service consumers are as follows:

The Session Management Function (SMF):

– supports (un)subscribing to notifications of subscribed event(s) from the NEF.

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

4.3.2 Service Operations

4.3.2.1 Introduction

Service operations defined for the Nnef_EASDeployment Service are shown in table 4.3.2.1-1.

Table 4.3.2.1-1: Nnef_EventExposure Service Operations

Service Operation Name	Description	Initiated by
Nnef_EASDeployment_Subscribe	This service operation is used by an NF service consumer to explicitly subscribe the notification of changes of EAS Deployment Information.	NF service consumer
Nnef_EASDeployment_Unsubscribe	This service operation is used by an NF service consumer to explicitly unsubscribe the notification of changes of EAS Deployment Information.	NF service consumer
Nnef_EASDeployment_Notify	This service operation is used by the NEF to provide subscribed event information, e.g.updated EAS Deployment Information to the NF service consumer.	NEF

4.3.2.2 Nnef_EASDeployment_Subscribe service operation

4.3.2.2.1 General

This service operation is provided by the NEF for NF consumers to explicitly subscribe the notification of changes of EAS Deployment Information.

4.3.2.2.2 Creating a new subscription

In order to subscribe to EAS Deployment Information change event, the SMF shall send an HTTP POST request message to the NEF for the "EAS Deployment Event Subscriptions" resource. The HTTP POST message shall include EasDeploySubData data structure as request body. The EasDeploySubData data structure shall include:

– Event Id in the "eventId" attribute;

– An notification correlation ID provided by the NF service consumer during the subscription as "notifId" attribute; and

– An URI to receive the subscribed EAS Deployment information change notifications as "notifUri" attribute.

and may include:

– an indicator to immediatedly report the current status of EAS Deployment Information if available, as "immRep" attribute;

– (list of) DNN and/or S-NSSAI combination as "dnnSnssaiInfos" attribute;

– identification of an application as "appId" attribute; and/or

– an internal Group Identifier as "interGroupId" attribute.

Upon receipt of the HTTP request from the SMF, if the SMF is validated, the NEF shall interact with the UDR by invoking the Nudr_DataRepository service as described in 3GPP TS 29.504 [20] to fetch the EAS Deployment Information in the application data in the UDR.

After receiving a successful response from the UDR, the NEF shall create a new subscription and assign a subscription identifier for the "Individual EAS Deployment Event Subscription" resource. Then the NEF shall send a HTTP "201 Created" response with EASDeploySubData data structure as response body and a Location header field containing the URI of the created individual subscription resource to the NF service consumer. If the immediate report indicator is included in the subscription request, the NEF shall include the current available status of EAS Deployment Information in the response body.

If the NEF receives an error code from the UDR, the NEF shall take proper error handling actions and shall respond to the SMF with a proper error status code.

4.3.2.3 Nnef_EASDeployment_Unsubscribe service operation

4.3.2.3.1 General

This service operation is used by an NF service consumer (i.e. SMF) to explicitly unsubscribe the notification of changes of EAS Deployment Information.

The following procedure using the Nnef_EASDeployment_Unsubscribe service operation is supported:

– unsubscription from the notification of changes of EAS Deployment Information.

4.3.2.3.2 Unsubscription of notification of changes of EAS Deployment Information

In order to delete an existing subscription to EAS Deployment Information change event, the NF service consumer shall send an HTTP DELETE request message to the individual resource URI "{apiRoot}/nnef-eas-deployment/v1/subscriptions/{subscriptionId}" in which the "{subscriptionId}" is the subscription correlation identifier of the existing subscription resource that is to be deleted.

The NEF shall delete the individual resource and shall respond to the NF service consumer with an HTTP "204 No Content" response message.

If the NEF cannot delete the individual resource, shall take proper error handling actions and shall respond to the NF service consumer with a proper error status code.

4.3.2.4 Nnef_EASDeployment_Notify service operation

4.3.2.4.1 General

The Nnef_EASDeployment_Notify service operation enables the NEF to notify the subscribed event information, e.g. updated EAS Deployment Information to the NF Consumer.

The following procedure using the Nnef_EASDeployment_Notify service operation is supported:

– notification about subscribed EAS Deployment Information change.

4.3.2.4.2 Notification of changes of EAS Deployment Information

If there is current status of EAS Deployment Information available and immediate report is required, the NEF may immediately provide a notification to the subscribed NF service consumer by sending an HTTP POST message that include the EasDeployInfoNotif data structure in the request body to notify the current status of EAS Deployment information to the NF service consumer.

If the immediate report is not required or the current status of EAS Deployment Information is not available, when the EAS Deployment information was changed, the NEF shall provide a notification to the subscribed NF service consumer by sending an HTTP POST message that include the EasDeployInfoNotif data structure in the request body to notify the EAS Deployment information changes to the NF service consumer.

The EasDeployInfoNotif data structure shall include the subscribed Event ID and the EAS Deployment Information.

Upon receipt of the EAS Deployment event notification, the NF service consumer shall respond with a "204 No Content" status code to confirm the received notification.