4 Access and Mobility Policy Control Service

29.5073GPP5G SystemAccess and Mobility Policy Control ServiceRelease 18Stage 3TS

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

4.1 Service Description

4.1.1 Overview

The Access and Mobility Policy Control Service, as defined in 3GPP TS 23.502 [3] and 3GPP TS 23.503 [4], is provided by the Policy Control Function (PCF).

This service provides access control and mobility management related policies to the NF service consumer and offers the following functionalities:

– policy creation based on a request from the NF service consumer during UE registration;

– notification of the NF service consumer of the updated policies which are subscribed; and

– deletion of the policy context for a UE.

4.1.2 Service Architecture

The 5G System Architecture is defined in 3GPP TS 23.501 [2]. The Policy and Charging related 5G architecture is also described in 3GPP TS 29.513 [7].

The Access and Mobility Policy Control Service (Npcf_AMPolicyControl) is part of the Npcf service-based interface exhibited by the Policy Control Function (PCF).

The known NF service consumer of the Npcf_AMPolicyControl service is the Access and Mobility Management Function (AMF).

The AMF accesses the Access and Mobility Policy Control Service at the PCF via the N15 Reference point. In the roaming scenario, the N15 reference point is located between the V-PCF in the visited network and the AMF.

Figure 4.1.2-1: Reference Architecture for the Npcf_AMPolicyControl Service; SBI representation

Figure 4.1.2-2: Non-roaming Reference Architecture for the Npcf_AMPolicyControl Service; reference point representation

Figure 4.1.3-2: Roaming reference Architecture for the Npcf_AMPolicyControl Service; reference point representation

4.1.3 Network Functions

4.1.3.1 Policy Control Function (PCF)

The Policy Control Function (PCF):

– Supports unified policy framework to govern network behaviour; and

– Provides Access and Mobility Management related policies to the NF service consumer that enforces them.

In the roaming scenario, the Visited Policy Control Function (V-PCF) provides the functions described in this clause towards the visited network.

4.1.3.2 NF Service Consumers

The Access and Mobility Management function (AMF) provides:

– Registration management;

– Connection management;

– Reachability management; and

– Mobility Management.

4.2 Service Operations

4.2.1 Introduction

Table 4.2.1-1: Operations of the Npcf_AMPolicyControl Service

Service operation name	Description	Initiated by
Npcf_AMPolicyControl_Create	Creates an AM Policy Association and provides corresponding policies to the NF service consumer.	NF service consumer (e.g. AMF)
Npcf_AMPolicyControl_Update	Updates an AM Policy Association and provides corresponding policies to the NF service consumer when a policy control request trigger is met or the AMF is relocated due to UE mobility and the old PCF is selected.	NF service consumer (e.g. AMF)
Npcf_AMPolicyControl_UpdateNotify	Provides updated policies to the NF service consumer.	PCF (V-PCF in roaming case)
Npcf_AMPolicyControl_Delete	Provides means for the NF service consumer to delete the AM Policy Association.	NF service consumer (e.g. AMF)

4.2.2 Npcf_AMPolicyControl_Create Service Operation

4.2.2.1 General

The procedure in the present clause is applicable when the NF service consumer (e.g. AMF) creates an AM policy association when the UE registers to the network, and when the AMF is relocated (between the different AMF sets) and the new AMF selects a new PCF. The procedure for the case where the AMF is relocated and the new AMF selects the old PCF is defined in clause 4.2.3.1.

The creation of an AM policy association only applies for normally registered UEs, i.e., it does not apply for Emergency Registered UEs.

Figure 4.2.2.1-1 illustrates the creation of a policy association.

Figure 4.2.2.1-1: Creation of a policy association

When a UE registers and a UE context is being established, the AMF can obtain Service Area Restrictions, RFSP index, subscribed UE-AMBR, subscribed UE-Slice-MBR(s) and GPSI(s) from the UDM during the Access and Mobility Subscription Data retrieval procedure, the list of NWDAF instance IDs used for the UE and their associated Analytic ID(s) consumed by the AMF and the allowed NSSAI and the Target NSSAI from local configuration or from the NSSF during the slice selection procedure and shall decide based on local policies whether to request policies from the PCF.

To request policies from the PCF, the NF service consumer (e.g. AMF) shall send an HTTP POST request with: "{apiRoot}/npcf-am-policy-control/v1/policies" as Resource URI and the PolicyAssociationRequest data structure as request body that shall include:

– Notification URI encoded as "notificationUri" attribute;

– SUPI encoded as "supi" attribute; and

– if the feature "SliceSupport" or the feature "DNNReplacementControl" is supported in the NF service consumer and the UE is registered via a 3GPP access, the allowed NSSAI in the 3GPP access encoded in the "allowedSnssais" attribute;

and that shall include when available:

– GPSI encoded as "gpsi" attribute;

– if the feature "MultipleAccessTypes" is not supported, the access type encoded as "accessType" attribute;

NOTE 1: In this Release, for SNPN-enabled UE registered in the SNPN, direct access to the SNPN is specified for 3GPP access only.

– Permanent Equipment Identifier (PEI) encoded as "pei" attribute;

– User Location Information encoded as "userLoc" attribute;

– UE Time Zone encoded as "timeZone" attribute;

– the identifier of the serving network (the PLMN Identifier or the SNPN Identifier)encoded as "servingPlmn" attribute;

NOTE 2: The SNPN Identifier consists of the PLMN Identifier and the NID.

– if the feature "MultipleAccessTypes" is not supported, the RAT type encoded as "ratType" attribute;

– Service Area Restrictions (see clause 4.2.2.3.1) derived from the Service Area Restrictions obtained from the UDM by mapping any service areas denoted by geographical information into Tracking Area Identities (TAIs) and encoded as "servAreaRes" attribute;

– RFSP index (see clause 4.2.2.3.2) as obtained from the UDM encoded as "rfsp" attribute;

– a list of Internal Group Identifiers encoded as "groupIds" attribute;

– if the NF service consumer is an AMF, the GUAMI encoded as "guami" attribute;

– if the NF service consumer is an AMF, the name of a service produced by the AMF that expects to receive information within Npcf_AMPolicyControl_UpdateNotify service operation encoded as "serviceName" attribute;

– Alternate or backup IPv4 Address(es) where to send Notifications encoded as "altNotifIpv4Addrs" attribute;

– Alternate or backup IPv6 Address(es) where to send Notifications encoded as "altNotifIpv6Addrs" attribute;

– Alternate or backup FQDN(s) where to send Notifications encoded as "altNotifFqdns" attribute;

– trace control and configuration parameters information encoded as "traceReq" attribute;

– if the feature "UE-AMBR_Authorization" is supported in the NF service consumer, the subscribed UE-AMBR (see clause 4.2.2.3.3) in the "ueAmbr" attribute;

– if the feature "DNNReplacementControl" is supported, the mapping of each S-NSSAI of the Allowed NSSAI to the corresponding S-NSSAI of the HPLMN encoded in the "mappingSnssais" attribute;

– if the feature "UE-Slice-MBR_Authorization" is supported in the NF service consumer, the subscribed UE-Slice-MBR for each subscribed S-NSSAI of the home PLMN mapping to a S-NSSAI of the serving PLMN if available (see clause 4.2.2.3.5) encoded in the "ueSliceMbrs" attribute; and.

– when the "EneNA" feature is supported, the list of NWDAF instance IDs used for the UE within the "nwdafInstanceIds" and their associated Analytic ID(s) within "nwdafEvents" consumed by the NF service consumer, included within the "nwdafDatas" attribute; and

– if the feature "TargetNSSAI" is supported in the NF service consumer, the Target NSSAI generated by the NF service consumer or received from the NSSF encoded in the "targetSnssais" attribute.

Upon the reception of this HTTP POST request, the PCF shall:

– assign a policy association ID;

– determine the applicable policy (taking into consideration and optionally modifying the possibly received UE-AMBR, UE-Slice-MBR(s) for the allowed NSSAI, Service Area Restrictions and/or RFSP index);

– for the successful case, send a HTTP "201 Created" response with the URI for the created resource in the "Location" header field

NOTE 3: The assigned policy association ID is part of the URI for the created resource and is thus associated with the SUPI.

and the PolicyAssociation data type as response body including:

– conditionally AMF Access and Mobility Policy (see clause 4.2.2.3), i.e.:

a) if the PCF received the "servAreaRes" attribute in the request, Service Area Restrictions encoded as "servAreaRes" attribute; and/or

b) if the PCF received the "rfsp" attribute in the request, RAT Frequency Selection Priority (RFSP) Index encoded as "rfsp" attribute; and/or

c) if the feature "UE-AMBR_Authorization" is supported and the PCF received the "ueAmbr" attribute in the request, the authorized UE-AMBR encoded as "ueAmbr" attribute;

d) if the feature "UE-Slice-MBR_Authorization" is supported and the PCF received the "ueSliceMbrs" attribute in the request, the corresponding authorized UE-Slice-MBR(s) encoded as "ueSliceMbrs" attribute; and/or

e) if the feature "AMInfluence" is supported, the PCF for the UE determines that the access and mobility policies may be influenced by the traffic of PDU session(s) and local operator policies indicate that the PCF for the UE shall subscribe with the PCF for the PDU session for established/terminated PDU session(s) event notifications via the AMF and the SMF, the PCF for the UE information within the "pcfUeInfo" attribute, and the DNN and S-NSSAI of the concerned PDU session(s) within the "matchPdus" attribute. The "pcfUeInfo" attribute shall include the PCF for the UE callback URI via which the PCF(s) for the PDU session shall send notifications about the related PDU session(s) established/terminated events within the "callbackUri" attribute, and if available, the associated PCF for the UE instance ID, PCF set ID, and the level of SBA binding within the "bindingInfo" attribute;

f) if the feature "5GAccessStratumTime" is supported and the PCF receives the access stratum time distribution parameters from the TSCTSF as defined in 3GPP TS 29.534 [26], the 5G access stratum time distribution parameters encoded as "asTimeDisParam" attribute as defined in clause 4.2.2.3.6;

– optionally one or several of the following Policy Control Request Trigger(s) encoded as "triggers" attribute (see clause 4.2.3.2):

a) Location change (tracking area);

b) Change of UE presence in PRA;

c) if the "SliceSupport" feature or the "DNNReplacementControl" feature is supported, change of allowed NSSAI;

d) if the "DNNReplacementControl" feature is supported, change of SMF selection information; and

e) if the "EneNA" feature is supported, change of NWDAF data;

f) if the "TargetNSSAI" feature is supported, Generation of Target NSSAI; and

– if the Policy Control Request Trigger "Change of UE presence in PRA" is provided, the presence reporting areas for which reporting is required encoded as "pras" attribute;

NOTE 4: If the PCF uses a Presence Reporting Area identifier referring to a Set of Core Network predefined Presence Reporting Areas as defined in 3GPP TS 23.501 [2], the PCF includes the identifier of this Presence Reporting Area set within the "praId" attribute.

– if the Policy Control Request Trigger "Change of SMF selection information" is provided, the SMF selection information representing the conditions upon which the AMF shall request a DNN replacement (see clause 4.2.2.3.4) encoded as "smfSelInfo" attribute;

– if the Policy Control Request Trigger "Generation of Target NSSAI" is provided, the RFSP Index associated with the Target NSSAI encoded as "targetRfsp" attribute;

– if errors occur when processing the HTTP POST request, apply error handling procedures as specified in clause 5.7 and according to the following provisions:

– if the user information received within the "supi" attribute is unknown, the PCF shall reject the request and include in an HTTP "400 Bad Request" response message the "cause" attribute of the ProblemDetails data structure set to "USER_UNKNOWN";

– if the PCF is, due to incomplete, erroneous or missing information in the request, not able to provision an AM policy decision, the PCF may reject the request and include in an HTTP "400 Bad Request" response message the "cause" attribute of the ProblemDetails data structure set to "ERROR_REQUEST_PARAMETERS".

– if the PCF rejects the AM policy association establishment, the NF service consumer shall apply the policy retrieved from the UDM if available; otherwise, the NF service consumer shall apply the operator configured policy.

If the PCF received a GUAMI, the PCF may subscribe to GUAMI changes using the AMFStatusChange service operation of the Namf_Communication service specified in 3GPP TS 29.518 [14], and it may use the Nnrf_NFDiscovery Service specified in 3GPP TS 29.510 [13] (using the obtained GUAMI and possibly service name) to query the other AMFs within the AMF set.

If the PCF received a "traceReq" attribute, it shall perform trace procedures as defined in 3GPP TS 32.422 [18].

If the PCF received the list of NWDAF instance IDs used for the UE in "nwdafInstanceIds" attribute and their associated Analytic IDs in "nwdafEvents" attribute included within the "nwdafDatas" attribute the PCF may select those NWDAF instances as described in 3GPP TS 29.513 [7].

The PCF may retrieve AF requirements on Access and Mobility policies from the UDR as specified in 3GPP TS 29.519 [17] and consider them for determining the Access and Mobility policies to be provisioned.

4.2.2.2 Void

4.2.2.2.0 Void

4.2.2.2.1 Void

4.2.2.2.2 Void

4.2.2.3 AMF Access and Mobility Policy

4.2.2.3.1 Service Area Restriction

If service area restrictions are enabled, the Service Area Restriction information is encoded using the "ServiceAreaRestriction" data type defined in 3GPP TS 29.571 [11] and consists of:

– a limited allowed area represented as:

a) the maximum number of allowed TAs that can be traversed encoded as "maxNumOfTAs" attribute; or

b) both of:

(i) a list of allowed Tracking Area Identities (TAIs) encoded as "tacs" attributes within the "areas" attribute; and

(ii) the "restrictionType" attribute set to "ALLOWED_AREAS"; or

c) both a) and b) above;

– or a limited allowed area represented as:

a) the maximum number of allowed TAs that can be traversed encoded as "maxNumOfTAsForNotAllowedAreas" attribute; or

b) all of:

(i) a list of not allowed Tracking Area Identities (TAIs) encoded as "tacs" attributes within the "areas" attribute; and

(ii) the "restrictionType" attribute set to "NOT_ALLOWED_AREAS"; and

(iii) the maximum number of allowed TAs that can be traversed encoded as "maxNumOfTAsForNotAllowedAreas" attribute;

– or a not allowed area represented as:

a) a list of not allowed Tracking Area Identities (TAIs) encoded as "tacs" attributes within the "areas" attribute; and

b) the "restrictionType" attribute set to "NOT_ALLOWED_AREAS".

When the "restrictionType" attribute is set to "NOT_ALLOWED_AREAS", the "maxNumOfTAs" attribute shall not be present.

When the "restrictionType" attribute is set to "ALLOWED_AREAS", the "maxNumOfTAsForNotAllowedAreas" attribute shall not be present.

When for a limited allowed area both, "maxNumOfTAs" and "areas" attributes are present, the "maxNumOfTAs" attribute represents the upper limit of the limited allowed area. The AMF may add any not yet visited tracking areas to the allowed area represented by the "areas" attribute until the total number of TAs reaches the "maxNumOfTAs" attribute value.

NOTE 1: The "maxNumOfTAs" attribute value represents the maximum number of TAs of the limited allowed area. When "maxNumOfTAs" attribute value is lower than the number of TAs in the "areas" attribute it represents the maximum number of TAs allowed inside the limited allowed area defined by the TAs contained in the "areas" attribute. When the "maxNumOfTAs" attribute value is higher than the number of TAs in the "areas" attribute it represents that additional TAs up to the "maxNumOfTAs" attribute value can be dynamically added to the area defined by the TAs contained in the "areas" attribute.

When for a limited allowed area the following three attributes are present:

– "maxNumOfTAsForNotAllowedAreas" attribute; and

– the "restrictionType" attribute set to "NOT_ALLOWED_AREAS"; and

– the "areas" attribute,

the "maxNumOfTAsForNotAllowedAreas" attribute represents the maximum number of TAs allowed in a limited allowed area outside the not allowed area represented in the "areas" attribute. The limited allowed area is dynamically calculated by the AMF, and the TAs outside of the dynamically calculated limited allowed area become not allowed TAs.

NOTE 2: Both, the "maxNumOfTAsForNotAllowedAreas" attribute and the "maxNumOfTAs" attribute, when present in a "ServiceAreaRestriction" data type instance that does not include the "areas" attribute and the "restrictionType" attribute, represent a maximum number of allowed TAs in a limited allowed area dynamically calculated by the AMF.

When the authorized service area restrictions result in an unlimited set of allowed tracking areas, the PCF shall include:

– an empty "servAreaRes" attribute; or

– the "restrictionType" attribute set to "NOT_ALLOWED_AREAS" and an empty "areas" attribute.

When the authorized service area restrictions result in an unlimited set of not-allowed tracking areas, the PCF shall include the "restrictionType" attribute set to "ALLOWED_AREAS" and an empty "areas" attribute.

NOTE 3: The "maxNumOfTAs" attribute and the "maxNumOfTAs" attribute are not used when the authorized service area restrictions result in an unlimited set of allowed or an unlimited set of not-allowed tracking areas.

4.2.2.3.2 RFSP Index

The RFSP Index is an index referring to a UE information used locally by the Access Network in order to apply specific radio resource management strategies. It shall be encoded using the RfspIndex data type defined in 3GPP TS 29.571 [11].

If the feature "TargetNSSAI" is supported and when the PCF receives the Target NSSAI from the NF service consumer, the PCF shall, if the Policy Control Request Trigger "Generation of Target NSSAI" is provisioned in the response, additionally provide the RFSP Index associated with the Target NSSAI.

In order for the PCF to determine the RFSP Index value that will be authorized, the PCF shall be configured with a mapping between the RAT Type and/or frequency value and the RFSP Index.

NOTE: The RFSP index value that will be authorized is determined based on operator policies that take into consideration e.g. accumulated usage, analytics information related to load level information per network slice instance, UE communication, user data congestion or service experience, etc.

Upon reception of the authorized RFSP index, the NF service consumer (e.g. AMF) shall choose the RFSP Index in use as described in 3GPP TS 23.501 [2] clause 5.3.4.3.1.

4.2.2.3.3 UE-AMBR

The UE-AMBR limits the aggregate bit rate that can be expected to be provided across all Non-GBR QoS Flows of a UE. It shall be encoded using the Ambr data type defined in 3GPP TS 29.571 [11].

4.2.2.3.4 SMF Selection Management

If the "DNNReplacementControl" feature is supported, when SMF Selection Management is enabled, the SMF selection information is encoded using the "SmfSelectionData" data type, which consists of:

– the conditions upon which the AMF shall request to the PCF the replacement of SMF selection data, which may include:

a) an indication of whether the AMF shall request DNN replacement when the UE requested an unsupported DNN during PDU session establishment encoded in the "unsuppDnn" attribute; and/or

b) a list of candidate DNNs for replacement encoded in the "candidates" map, where:

i) the key of the map is the S-NSSAI; and

ii) each entry of the map is of "CandidateForReplacement" data type, which:

– shall include the S-NSSAI encoded in the "snssai" attribute; and

– may include the list of candidate DNNs for the S-NSSAI encoded in the "dnns" attribute;

NOTE 1: The S-NSSAIs included in the map are S-NSSAIs of the allowed NSSAI valid in the serving network. The PCF keeps updated information of the allowed NSSAI valid in the serving network by subscribing to the policy control request trigger Change of allowed NSSAI of the served UE.

NOTE 2: When the PCF provides URSP rules (see 3GPP TS 29.525 [29]) to the UE with new DNN information and in order to provide uniform service experience for UEs from earlier Releases, the candidate DNNs for replacement will consider those included within the traffic descriptors in addition to those included as part of the Route Selection Descriptor(s) of the URSP rule(s) provided to the UE.

– and,

a) when included within the Npcf_AMPolicyControl_Update request, the UE requested DNN and S-NSSAI at PDU session establishment that matched an entry of the "candidates" map, encoded in the "dnn" attribute and in the "snssai" attribute respectively, and the mapping to the home S-NSSAI encoded in the "mappingSnssai" attribute if available; and

b) when included within the Npcf_AMPolicyControl_Update response, the PCF selected DNN encoded in the "dnn" attribute;

NOTE 2: The PCF can select the same DNN and S-NSSAI as the UE requested DNN and S-NSSAI. When the PCF returns an unsupported DNN, the AMF applies internal policies to reject the PDU session establishment.

When the "dnns" attribute is omitted in an entry of the "candidates" map it represents that the AMF shall invoke the procedure for any UE request matching the S-NSSAI value included in the "snssai" attribute.

4.2.2.3.5 UE-Slice-MBR

The UE-Slice-MBR limits the aggregate bit rate that can be expected to be provided across all GBR and Non-GBR QoS Flows of a UE for an S-NSSAI. It shall be encoded using the SliceMbr data type defined in 3GPP TS 29.571 [11].

4.2.2.3.6 5G access stratum time distribution

If the feature "5GAccessStratumTime" is supported and the PCF receives the access stratum time distribution parameters from the TSCTSF as defined in 3GPP TS 29.534 [26], the 5G access stratum time distribution parameters are encoded using the "asTimeDisParam" attribute of the "AsTimeDistributionParam" data type, which consists of:

– an indication of whether the 5G access stratum time distribution is enabled encoded in the "asTimeDistInd" attribute if applicable; and

– the Uu Time synchronization error budget encoded in the "uuErrorBudget" attribute if applicable.

If the PCF receives multiple time synchronization error budgets for a given UE, the PCF shall encode the most stringent error budget within the "uuErrorBudget" attribute.

If the PCF receives the removal of the access stratum time distribution parameters from the TSCTSF as defined in 3GPP TS 29.534 [26] and there are no other access stratum time distribution parameters from other requests for the same UE, the PCF shall provide the "asTimeDisParam" attribute set to NULL.

4.2.3 Npcf_AMPolicyControl_Update Service Operation

4.2.3.1 General

The procedure in the present clause is applicable when the NF service consumer modifies an existing AM policy association (including the case where the AMF is relocated and the new AMF selects the old PCF to maintain the policy association and to update the Notification URI).

Figure 4.2.3.1-1 illustrates the update of a policy association.

Figure 4.2.3.1-1: Update of a policy association

The AMF as NF service consumer invokes this procedure when a policy control request trigger (see clause 4.2.3.2) occurs. When a policy control request trigger that does not require the subscription as defined in table 5.6.3.3-1 (e.g. Service Area Restriction change trigger) occurs, the NF service consumer (e.g. AMF) shall always invoke the procedure. When a policy control request trigger requires the subscription as defined in table 5.6.3.3-1 (e.g. location change trigger) occurs, the NF service consumer shall only invoke the procedure if the PCF has subscribed to that event trigger.

If an AMF knows by implementation specific means that the UE context has been transferred to an AMF with another GUAMI within the AMF set, it may also invoke this procedure to update the Notification URI and the GUAMI.

NOTE 1: Either the old or the new AMF can invoke this procedure.

During the AMF relocation, if the new AMF received the resource URI of the individual AM Policy from the old AMF and selects the old PCF, the new AMF shall also invoke this procedure to update the Notification URI and the GUAMI. The new AMF may also update the alternate or backup IP addresses. If the feature "FeatureRenegotation" is supported, the new AMF may perform feature renegotiation, as described in clause 4.2.3.4.

To request policies from the PCF, to update the Notification URI, to renegotiate features, to update the trace control configuration and/or to request the termination of trace, the NF service consumer (e.g. AMF) shall request the update of the AM Policy Association by providing the relevant parameters about the UE context by sending an HTTP POST request with "{apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId}/update" as Resource URI and the PolicyAssociationUpdateRequest data structure as request body that shall include:

– at least one of the following:

1. a new Notification URI encoded in the "notificationUri" attribute;

2. observed Policy Control Request Trigger(s) (see clause 4.2.3.2) encoded as "triggers" attribute;

3. if a Service Area restriction change occurred, the Service Area Restrictions (see clause 4.2.2.3.1) as obtained from the UDM encoded as "servAreaRes" attribute;

4. if a RFSP index change occurred, the RFSP index (see clause 4.2.2.3.2) as obtained from the UDM encoded as "rfsp" attribute;

5. if a UE location change occurred and the Policy Control Request Trigger "Location change" was provided, the UE location encoded as "userLoc" attribute;

6. if the Policy Control Request Trigger "Change of UE presence in PRA" was provided, the current presence status of the UE for the presence reporting areas for which reporting was requested, if not previously provided, or the presence reporting areas for which reporting was requested and the status has changed encoded as "praStatuses" attribute.

NOTE 2: If the PCF included the identifer of a Core Network predefined Presence Reporting Area Set within the "praId" attribute during the subscription to changes of UE presence in PRA, the AMF only provides the presence reporting area information corresponding to the concerned individual Presence Reporting Area Identifier(s) within the Set. The "praId" attribute within each returned "PresenceInfo" data type hence includes the identifier of the concerned individual Presence Reporting Area.

7. if the trace control configuration needs to be updated, trace control and configuration parameters information encoded as "traceReq" attribute;

8. if trace needs to be terminated, the "traceReq" attribute set to the Null value;

9. if the "SliceSupport" feature or the "DNNReplacementControl" feature is supported, the UE is registered via 3GPP access, the allowed NSSAI changed, and the Policy Control Request Trigger "Change of allowed NSSAI" was provided, then the allowed NSSAI encoded in the "allowedSnssais" attribute;

10. for AMF relocation scenarios, if available, alternate or backup IPv4 Address(es) where to send Notifications encoded as "altNotifIpv4Addrs" attribute;

11. for AMF relocation scenarios, if available, alternate or backup IPv6 Address(es) where to send Notifications encoded as "altNotifIpv6Addrs" attribute;

12. for AMF relocation scenarios, if available, alternate or backup FQDN(s) where to send Notifications encoded as "altNotifFqdns" attribute;

13. for AMF relocation scenarios, the GUAMI encoded as "guami" attribute;

NOTE 3: An alternate NF service consumer than the one that requested the generation of the subscription resource can send the request. For instance, an AMF as service consumer can change.

14. if the feature "UE-AMBR_Authorization" is supported, and a subscribed UE-AMBR change occurred, the UE-AMBR (see clause 4.2.2.3.3) as obtained from the UDM encoded as "ueAmbr" attribute;

15. if the feature "DNNReplacementControl" is supported, DNN replacement applies and the Policy Control Request Trigger "Change of SMF selection information" was provided, the "smfSelInfo" attribute including:

– the UE requested DNN in the "dnn" attribute; and

– the UE requested S-NSSAI in the "snssai" attribute and, if available, the corresponding mapped home S-NSSAI in the "mappingSnssai" attribute;

when:

– the UE requested an unsupported DNN and the "unsuppDnn" attribute is set to "true"; or

– the UE requested DNN and S-NSSAI matched one of the S-NSSAI and DNN provided in the "candidates" attribute; and

16. if feature "DNNReplacementControl" is supported, the UE is registered via 3GPP access, the Allowed NSSAI changed and/or the mapping of a S-NSSAI of the Allowed NSSAI to the corresponding S-NSSAI of the HPLMN changed, and the Policy Control Request Trigger" Change of allowed NSSAI" was provided, then the mapping of each S-NSSAI of the Allowed NSSAI to the corresponding S-NSSAI of the HPLMN encoded in the "mappingSnssais" attribute;

NOTE 4: When the feature "DNNReplacementControl" is supported, the AMF applies DNN replacement for non-roaming scenarios and LBO. For a PDU session with home routed roaming, whether to perform DNN replacement is based on operator agreement.

17. if feature "UE-Slice-MBR_Authorization" is supported, and a subscribed UE-Slice-MBR change occurred, the subscribed UE-Slice-MBR for each subscribed S-NSSAI of the home PLMN mapping to a S-NSSAI of the serving PLMN (see clause 4.2.2.3.5) encoded in the "ueSliceMbrs" attribute;

18. if the feature "EneNA" is supported and an NWDAF information change occurred, the list of NWDAF instance IDs used for the UE within the "nwdafInstanceIds" and their associated Analytic ID(s) within "nwdafEvents" with the updated values included within the "nwdafDatas" attribute.

NOTE 5: The NF service consumer provides the complete updated list of NWDAF instance IDs and associated Analytic ID(s) used for the UE. If all NWDAF data is deleted an empty list is included.

19. if the feature "TargetNSSAI" is supported, a new Target NSSAI is generated and the Policy Control Request Trigger "Generation of Target NSSAI" is provided, the new generated Target NSSAI encoded in the "targetSnssais" attribute.

Upon the reception of the HTTP POST request, the PCF shall:

– update the corresponding individual AM Policy resource based on the information provided by the NF service consumer;

– determine the applicable policy based on local policy;

– for the successful case, send a HTTP "200 OK" response with the PolicyUpdate data type as body with possible updates for that applicable policy and Policy Control Request Trigger(s) encoded as described in clause 4.2.3.3 and according to the following provisions:

a) if the PCF received the "servAreaRes" attribute in the request, Service Area Restrictions encoded as "servAreaRes" attribute;

b) if the PCF received the "rfsp" attribute in the request, RAT Frequency Selection Priority (RFSP) Index encoded as "rfsp" attribute;

c) if the feature "UE-AMBR_Authorization" is supported and the PCF received the "ueAmbr" attribute in the request, UE-AMBR encoded as "ueAmbr" attribute;

d) if the PCF received the "smfSelInfo" attribute in the request, the "smfSelInfo" attribute encoding the PCF selected DNN in the "dnn" attribute corresponding to the S-NSSAI received in the "snssai" attribute;

NOTE 6: A PolicyUpdate data structure with only mandatory attribute(s) is included in the "200 OK" response when the PCF decides not to update the policies.

e) if the feature "UE-Slice-MBR_Authorization" is supported and the PCF received the "ueSliceMbrs" attribute in the request, the corresponding authorized UE-Slice-MBR(s) encoded as "ueSliceMbrs" attribute; and/or

f) if the feature "TargetNSSAI" is supported and the PCF received the "targetSnssais" attribute in the request, the RFSP Index associated with the Target NSSAI encoded as "targetRfsp" attribute;

– if errors occur when processing the HTTP POST request, apply error handling procedures as specified in clause 5.7 and according to the following provisions:

a) if the PCF is, due to incomplete, erroneous or missing information in the request, not able to provision an AM policy decision, the PCF may reject the request and include in an HTTP "400 Bad Request" response message the "cause" attribute of the ProblemDetails data structure set to "ERROR_REQUEST_PARAMETERS".

b) if the "ES3XX" feature is supported and the PCF (service) instance has changed, the PCF may respond with an HTTP 3xx redirect response pointing to a new PCF (service) instance as defined in clause 6.5.3.3 of 3GPP TS 29.500 [5].

If the PCF received a "traceReq" attribute, it shall perform trace procedures as defined in 3GPP TS 32.422 [18].

If the AMF received the request of removal of Service Area Restrictions and/or RFSP Index and/or UE-AMBR and/or UE-Slice-MBR(s) from the UDM, the AMF shall remove the authorized Service Area Restrictions and/or RFSP Index and/or UE-AMBR and/or UE-Slice-MBR(s) provisioned by the PCF and apply the configured Service Area Restrictions and/or RFSP Index and/or UE-AMBR and/or UE-Slice-MBR(s) at the AMF without interacting with the PCF.

If feature "DNNReplacementControl" is supported and the AMF received the update of the SMF selection information within the "smfSelInfo" attribute in the response, the AMF shall apply the updated SMF selection information to the new PDU Sessions only, i.e. already established PDU Sessions are not affected.

If the feature "AMInfluence" is supported, the PCF determines that the access and mobility policies may be influenced by the traffic of a PDU session(s), e.g. based on the received policy control request trigger(s), and local operator policies indicate the PCF for the UE shall subscribe with the PCF for the PDU session for established/terminated PDU session(s) event notifications, the PCF shall provision/update the AMF with the PCF for the UE information within the "pcfUeInfo" attribute and the complete list of S-NSSAI and DNN combinations within the "matchPdus" attribute. The AMF shall then update the affected established PDU sesssion(s), by forwarding the received PCF for the UE information for the PDU session(s) matching the new S-NSSAI and DNN combination(s) and removing the previously provided PCF for the UE information for the PDU session(s) matching the removed S-NSSAI and DNN combination(s) as defined in 3GPP TS 29.502 [31].

When the feature "AMInfluence" is supported, and the SBA binding indication information for the PCF instance changes, the PCF may update the previously provided information in the AMF. The AMF shall apply the updated PCF callback information to the new PDU Sessions only, i.e., already established PDU sessions are not affected.

If the PCF received a new GUAMI, the PCF may subscribe to GUAMI changes using the AMFStatusChange service operation of the Namf_Communication service specified in 3GPP TS 29.518 [14], and it may use the Nnrf_NFDiscovery Service specified in 3GPP TS 29.510 [13] (using the obtained GUAMI and possibly service name) to query the other AMFs within the AMF set.

If the PCF received a "servAreaRes" attribute which resulted to a change of the Service Area Restrictions, it shall send notifications to any NF Service Consumer(s) (e.g. AF) that have subscribed to the related event by using the Npcf_AMPolicyAuthorization service (see TS 29.534 [26]) and/or the Npcf_EventExposure service ((see TS 29.523 [28]).

If the PCF received a new list of NWDAF instance IDs used for the UE in "nwdafInstanceIds" attribute and their associated Analytic IDs in "nwdafEvents" attribute included within the "nwdafDatas" attribute the PCF may select those NWDAF instances based on this new list as described in 3GPP TS 29.513 [7].

4.2.3.2 Policy Control Request Triggers

The following Policy Control Request Triggers are defined (see clause 6.1.2.5 of 3GPP TS 23.503 [4]):

– "LOC_CH", i.e. location change (tracking area): the tracking area of the UE has changed;

– "PRA_CH", i.e. change of UE presence in PRA: the UE is entering/leaving a Presence Reporting Area, this includes reporting the initial status at the time the request for reports is initiated;

– "SERV_AREA _CH", i.e. Service Area Restriction change: the UDM notifies the AMF that the subscribed service area restriction information has changed;

– "RFSP_CH", i.e. RFSP index change: the UDM notifies the AMF that the subscribed RFSP index has changed;

– "ALLOWED_NSSAI_CH", i.e. change of allowed NSSAI of the served UE;

NOTE 1: The "ALLOWED_NSSAI_CH" trigger only applies if the "SliceSupport" feature or the "DNNReplacementControl" feature is supported.

– "UE_AMBR_CH", i.e. UE-AMBR change: the UDM notifies the AMF that the subscribed UE-AMBR has changed;

NOTE 2: The "UE_AMBR_CH" trigger only applies if the "UE-AMBR_Authorization" feature is supported.

– "SMF_SELECT_CH", i.e. SMF selection information change: UE request for an unsupported DNN or UE request for a DNN within the list of DNN candidates for replacement per S-NSSAI;

NOTE 3: The "SMF_SELECT_CH" trigger only applies if the "DNNReplacementControl" feature is supported and "ALLOWED_NSSAI_CH" trigger is also subscribed.

– "ACCESS_TYPE_CH", i.e. the access type change: the AMF notifies that the access type and the RAT type combinations available in the AMF for a UE with simultaneous 3GPP and non-3GPP connectivity has changed;

NOTE 4: The "ACCESS_TYPE_CH" trigger only applies if the "MultipleAccessTypes" feature is supported as specified in Annex B.

– "UE_SLICE_MBR_CH", i.e. UE-Slice-MBR change: the AMF notifies for any changes in the subscribed UE-Slice-MBR for each subscribed S-NSSAI of the home PLMN mapping to a S-NSSAI of the serving PLMN;

NOTE 5: The "UE_SLICE_MBR_CH" trigger only applies if the "UE-Slice-MBR_Authorization" feature is supported.

– "NWDAF_DATA_CH", i.e. NWDAF Data change:the list of NWDAF Instance IDs and/or their associated Analytics IDs consumed by the AMF have changed; and

NOTE 6: The "NWDAF_DATA_CH" trigger only applies if the "EneNA" feature is supported.

– "TARGET_NSSAI", i.e. Generation of Target NSSAI: the NF service consumer notifies that the Target NSSAI was generated.

NOTE 7: The "TARGET_NSSAI" trigger only applies if the "TargetNSSAI" feature is supported.

4.2.3.3 Encoding of updated policy

Updated policies shall be encoded within the PolicyUpdate data type that may include:

– AMF Access and Mobility Policy (see clause 4.2.2.3) Service Area Restriction encoded as "servAreaRes" attribute;

– AMF Access and Mobility Policy (see clause 4.2.2.3) RFSP Index encoded as "rfsp" attribute and RFSP Index associated with the Target NSSAI encoded as "targetRfsp" attribute;

– if the "UE-AMBR_Authorization" feature is supported, AMF Access and Mobility Policy (see clause 4.2.2.3) UE-AMBR encoded as "ueAmbr" attribute;

– if the "UE-Slice-MBR_Authorization" feature is supported, AMF Access and Mobility Policy (see clause 4.2.2.3) UE-Slice-MBR(s) encoded as "ueSliceMbrs" attribute;

NOTE: PCF can stop applying policies to already provided attributes under PolicyUpdate data type. In that case, PCF will modify those attributes by e.g. providing configured values. How the PCF gets those values is out of specification.

– if the "DNNReplacementControl" feature is supported, AMF Access and Mobility Policy (see clause 4.2.2.3) SMF selection information encoded as "smfSelInfo" attribute;

– updated Policy Control Request Trigger(s) (see clause 4.2.3.2) encoded as "triggers" attribute i.e.:

1) either a new complete list of applicable Policy Control Request Trigger(s) including one or several of the following:

a) Location change (tracking area); and/or

b) Change of UE presence in PRA; and/or

c) if the "SliceSupport" feature or the "DNNReplacementControl" feature is supported, change of allowed NSSAI; and/or

d) if the "DNNReplacementControl" feature is supported, SMF selection information change; or

2) a "NULL" value to request the removal of all previously installed Policy Control Request Trigger(s); and

– if the Policy Control Request Trigger "Change of UE presence in PRA" is provided or if that trigger was already set but the requested presence reporting areas need to be changed, the presence reporting areas for which reporting is required encoded as "pras" attribute encoded as follows:

a) A new entry shall be added by supplying a new identifier as key and the corresponding PresenceInfo data type instance with complete contents as value as an entry within the map.

b) An existing entry shall be modified by supplying the existing identifier as key and the PresenceInfo data type instance with complete contents as value as an entry within the map.

c) An existing entry shall be deleted by supplying the existing identifier as key and "NULL" as value as an entry within the map.

d) For an unmodified entry, no entry needs to be provided within the map; and

– if the Policy Control Request Trigger "Change of UE presence in PRA" is removed, the presence reporting areas for which reporting was required shall be removed by providing the "pras" attribute with "NULL" as value.

– if the Policy Control Request Trigger "SMF selection information change" is provided or if that trigger was already set and the indication of DNN replacement when the requested DNN is unknown needs to be set or changed, the "unsuppDnn" attribute within "smfSelInfo" attribute shall be provided including the appropriate value.

– if the Policy Control Request Trigger "SMF selection information change" is provided or if that trigger was already set and the list of candidate DNNs for replacement needs to be set or changed, the "candidates" attribute within the "smfSelInfo" attribute is encoded as follows:

a) A new entry shall be added by supplying a new S-NSSAI as key and the corresponding CandidateForReplacement data type instance with complete contents as value as an entry within the map.

b) An existing entry shall be modified by supplying the existing S-NSSAI as key and the CandidateForReplacement data type instance with complete contents as value as an entry within the map.

c) An existing entry shall be deleted by supplying the existing S-NSSAI as key and "NULL" as value as an entry within the map.

d) For an unmodified entry, no entry needs to be provided within the map;

e) The complete list of candidate DNNs for which reporting is required shall be removed by providing the "candidates" attribute with "NULL" as value.

– if the Policy Control Request Trigger "SMF selection information change" is removed, the candidate DNNs for which reporting was required shall be removed by providing the "smfSelInfo" attribute with "NULL" as value.

4.2.3.4 Feature renegotiation during AMF relocation

During the AMF relocation, if the new AMF received the resource URI of the individual AM Policy from the old AMF and selects the old PCF, and the feature "FeatureRenegotation" is supported, the new AMF shall invoke the update of the policy association as described in clause 4.2.3.1 with the following differences:

– The new AMF shall include in the PolicyAssociationUpdateRequest data structure sent in the HTTP POST request:

a. the "suppFeat" attribute with the AMF supported features; and

b. for each supported feature, the required feature information elements as specified in clause 4.2.2.1, if applicable.

NOTE: When the new AMF received from the old AMF the subscription to policy control request trigger(s) that depend on feature control, and a policy control request trigger is met, the required feature information included in the update request contains the report of the met policy control request trigger.

– Upon reception of the HTTP POST request, the PCF shall update the "Individual AM Policy Association" resource, determine the applicable policy and include in the PolicyUpdate data structure sent in the HTTP POST response:

a. the "suppFeat" attribute with the negotiated features; and

b. the complete "Individual AM Policy Association" resource representation, as specified in clause clause 4.2.2.1.

Editor’s Note: It is FFS whether other differences in relation to the update procedure specified in 4.2.3.1 need to be specified (e.g., specific error handling).

4.2.4 Npcf_AMPolicyControl_UpdateNotify Service Operation

4.2.4.1 General

The PCF may decide to update policies or to request the termination of the policy association and shall then use an Npcf_AMPolicyControl_UpdateNotify service operation.

The following procedures using the Npcf_AMPolicyControl_UpdateNotify service operation are supported:

– policy update notification; and

– request for termination of the policy association.

4.2.4.2 Policy update notification

Figure 4.2.4.2-1 illustrates the policy update notification.

Figure 4.2.4.2-1: policy update notification

The PCF may decide to update policy control request trigger(s) and/or Access and Mobility policies related to an Individual AM Policy Association, e.g. in response to information provided to the PCF via the Npcf_AMPolicyAuthorization service (see 3GPP TS 29.534 [26]), to notification provided by the Nbsf_Management Service about the registration/deregistration of the PCF for a PDU session (see 3GPP TS 29.521 [30]) or to notifications provided by the Npcf_PolicyAuthorization service (see 3GPP TS 29.514 [25]), in response to a notification received from UDR about new or updated AF requirements on Access and Mobility polices (see 3GPP TS 29.519 [17]), or in response to an internal trigger within the PCF. The PCF shall send for this purpose an HTTP POST request with "{notificationUri}/update" as URI (where the Notification URI was previously supplied by the NF service consumer) and the PolicyUpdate data structure as request body encoded as described in clause 4.2.3.3.

Upon the reception of the HTTP POST request, the NF service consumer shall enforce the received updated policy.

In case of a successful update notification:

– if the feature "ImmediateReport" is supported and the PCF provisioned the policy control request triggers related to access type change, PRA change, allowed NSSAI change or location change, a "200 OK" response code and a response body with the corresponding available information in the "AmRequestedValueRep" data structure shall be returned in the response;

– otherwise, a "204 No Content" response code shall be returned in the response.

If errors occur when processing the HTTP POST request, the NF service consumer shall send an HTTP error response as specified in clause 5.7.

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 [5].

If the AMF as NF service consumer is not able to handle the notification but knows by implementation specific means that another AMF is able to handle the notification, it shall reply with an HTTP "307 Temporary redirect" response pointing to the URI of the new AMF. If the AMF is not able to handle the notification but another unknown AMF could possibly handle the notification, it shall reply with an HTTP "404 Not found" error response.

If the PCF receives a "307 Temporary redirect" response, the PCF shall resend the failed policy update notification request using the received URI in the Location header field as Notification URI. Subsequent policy update notifications, triggered after the failed one, shall be sent to the Notification URI provided by the NF service consumer during the corresponding policy association creation/update.

If the PCF becomes aware that a new AMF is requiring notifications (e.g. via the "404 Not found" response, via Namf_Communication service AMFStatusChange Notifications, see 3GPP TS 29.518 [14], or via link level failures), and the PCF knows alternate or backup IPv4, IPv6 Addess(es) or FQDN(s) where to send Notifications (e.g. via "altNotifIpv4Addrs", "altNotifIpv6Addrs" or "altNotifFqdns" attributes received when the policy association was created, via AMFStatusChange Notifications or via the Nnrf_NFDiscovery Service specified in 3GPP TS 29.510 [13] (using the service name and GUAMI obtained during the creation of the subscription) to discover the other AMFs within the AMF set), the PCF shall exchange the authority part of the corresponding Notification URI with one of those addresses and shall use that URI in any subsequent communication.

If the PCF received a "404 Not found" response, the PCF should resend the failed policy update notification request to that URI.

If the feature "DNNReplacementControl" is supported and the AMF received the update of the SMF selection information within the "smfSelInfo" attribute in the request, the AMF shall apply the updated SMF selection information to the new PDU Sessions only, i.e. already established PDU Sessions are not affected.

If the feature "AMInfluence" is supported, the PCF determines that the access and mobility policies may be influenced by the traffic of a PDU session(s) based on an AF request, UDR notification or other internal policies, and local operator policies indicate the PCF for the UE shall subscribe with the PCF for the PDU session for established/terminated PDU session(s) event notifications, the PCF for the UE shall provision/update the AMF with the PCF for the UE information within the "pcfUeInfo" attribute and the complete list of S-NSSAI and DNN combinations within the "matchPdus" attribute. The AMF shall update the affected established PDU sesssions, forwarding the received PCF for the UE information for the PDU session(s) matching the new S-NSSAI and DNN combination(s), and removing the previously provided PCF for the UE information for the PDU session(s) matching the removed S-NSSAI and DNN combination(s) as defined in 3GPP TS 29.502 [31].

If the PCF changed the Service Area Restrictions as part of the policy update, it shall send notifications to any NF Service Consumer(s) (e.g. AF) that have subscribed to the related event by using the Npcf_AMPolicyAuthorization service (see TS 29.534 [26]) and/or the Npcf_EventExposure service (see TS 29.523 [28]).

If the feature "5GAccessStratumTime" is supported and the PCF receives the access stratum time distribution parameters or removal of the access stratum time distribution parameters from the TSCTSF as defined in 3GPP TS 29.534 [26], the PCF may provision, update or remove the 5G access stratum time distribution parameters by provisioning the "asTimeDisParam" attribute as defined in clause 4.2.2.3.6. The AMF shall provision the 5G access stratum time distribution parameters to the NG-RAN when receiving it from the PCF.

4.2.4.3 Request for termination of the policy association

Figure 4.2.4.3-1 illustrates the request for a termination of the policy association.

Figure 4.2.4.3-1: request for a termination of the policy association

The PCF may request the termination of the policy association and shall then send an HTTP POST request with "{notificationUri}/terminate" as URI (where the Notification URI was previously supplied by the NF service consumer) and the TerminationNotification data structure as request body that shall include:

– the policy association ID encoded as "polAssoId" attribute; and

– the cause why the PCF requests the termination of the policy association encoded as "cause" attribute.

Upon the reception of the HTTP POST request, the NF service consumer shall:

– either send a HTTP "204 No Content" response for the successful processing of the HTTP POST request or an appropriate failure response; and

– if errors occur when processing the HTTP POST request, send an HTTP error response as specified in clause 5.7; or

– if the feature "ES3XX" is supported, and the NF service consumer determines the received HTTP POST request needs to be redirected, send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [5].

After the successful processing of the HTTP POST request, the NF service consumer shall remove the context related to the policy association but still apply the provisioned AM policies to the UE and invoke the Npcf_AMPolicyControl_Delete Service Operation defined in clause 4.2.5 to terminate the policy association.

If the PCF receives a "307 Temporary redirect" response, the PCF shall resend the failed request for termination of the policy association using the received URI in the Location header field as Notification URI.

If the PCF becomes aware that a new AMF is requiring notifications (e.g. via the "404 Not found" response, via Namf_Communication service AMFStatusChange Notifications, see 3GPP TS TS 29.518 [14], or via link level failures), and the PCF knows alternate or backup IPv4, IPv6 Address(es) or FQDN(s) where to send Notifications (e.g. via "altNotifIpv4Addrs", "altNotifIpv6Addrs" or "altNotifFqdns" attributes received when the policy association was created, via AMFStatusChange Notifications or via the Nnrf_NFDiscovery Service specified in 3GPP TS 29.510 [13] (using the service name and GUAMI obtained during the creation of the subscription) to discover the other AMFs within the AMF set), the PCF shall exchange the authority part of the corresponding Notification URI with one of those addresses and shall resend the failed request for termination of the policy association to that URI.

If the PCF received a "404 Not found" response, the PCF should resend the failed request for termination of the policy association to that URI.

4.2.5 Npcf_AMPolicyControl_Delete Service Operation

Figure 4.2.5-1 illustrates the deletion of a policy association.

Figure 4.2.5-1: Deletion of a policy association

The AMF as NF service consumer requests that the policy association is deleted when the corresponding UE context is terminated, e.g. during UE de-registration from the network, or when the UE moves from 5GS to EPS and the UE is not connected to the 5GC over a non-3GPP access.

During the AMF relocation, the old AMF shall invoke this procedure when:

– the resource URI of the "Individual AM Policy Association" resource is not transferred to the new AMF; or

– the new AMF informs the old AMF that the "Individual AM Policy Association" resource is not being reused (i.e. the old PCF is not being reused).

To request that the policy association is deleted, the NF service consumer (e.g. AMF) shall send an HTTP DELETE request with "{apiRoot}/npcf-am-policy-control/v1/policies/{polAssoId}" as Resource URI.

Upon the reception of the HTTP DELETE request, the PCF shall:

– delete the policy association;

– send either an HTTP "204 No Content" response indicating the success of the deletion or an appropriate failure response; and

– if errors occur when processing the HTTP DELETE request, send an HTTP error response as specified in clause 5.7; or

– if the feature "ES3XX" is supported, and the PCF determines the received HTTP DELETE request needs to be redirected, send an HTTP redirect response as specified in clause 6.10.9 of 3GPP TS 29.500 [5].