The PCF interfaces with the User Data Repository (UDR) to receive subscriber-related policies for User Equipment (UE) attach and session establishment. When a UE attaches to the network, AMF requires AM policies of the subscriber from PCF for the UE. Similarly, when a UE makes a PDU Session, SMF requires policy rules from PCF. Subscriber attributes are stored in the UDR. PCF communicates with UDR to receive these attributes which are used in the evaluation of policies.

PCF invokes the Nudr_DataRepository service to retrieve the AM and SM Policy attributes. PCF carries out the discovery of UDR URL through the Nnrf_NFDiscovery service which is NRF service.

This section describes how this feature works.

The User Data Repository (UDR) provisions PCF to retrieve the data stored in the UDR through the Nudr_DataRepository service. The service is also responsible for enabling the NF to subscribe and unsubscribe to the data change notifications from UDR. In particular to PCF, the Nudr_DataRepository service provides the following retrieve services to access policy control-related subscription information and application-specific information that is stored in the UDR:

• Subscription to notifications from the UDR on changes in the policy control-related subscription information.

• Subscription to the UDR for the AF requests targeting a DNN and S-NSSAI or a group of UEs (roaming UEs for LBO case) that are identified by an Internal Group Identifier.

• Subscription to notifications from the UDR on the update of AF requests targeting a DNN and S-NSSAI or a group of UEs (roaming UEs for LBO case) identified by an Internal Group Identifier.

The N36 reference point is defined for the interactions between PCF and UDR in the following reference point representation.

This section describes how to configure the UDR base URL discovery.

You must configure the UDR base URL for discovering profiles. The base URL aids in navigating to the mapped UDR. In the absence of the UDR base URL, the NRF's base URL is queried for the UDR base URL on the discovered profiles.

To configure the UDR base URL, use the following configuration in the Policy Ops Center console:

config 
  nrfDiscovery 
    nfType 
       locality 
          client client_name 
          geoServer server_name 
          preferredServer server_name   
       nrfDiscoveryGroup 
         subscriptionEnabled [ true | false ] 
         subscriptionExtension extension_count 
         type nf_type 
         end 

NOTES:

• nrfDiscovery —Enters the NRF discovery configuration mode.

• locality —Enters the locality configuration mode. The PCF REST endpoint considers the locality configuration.

• client client_locality —Specify the client locality of used by the NRF endpoint.

• geoServer server_name —Specify the geo redundant site of the preferred locality.

• preferredServer preferred_locality —Specify the server that is configured as the preferred server. Preferred locality takes precedence over the geo locality while using the service of the discovered NF (UDR).

• nrfDiscoveryGroup —Enters the NRF discovery group configuration.

• subscriptionEnabled [ true | false ] —Configures the subscription capability.

• subscriptionExtension extension_count —Specify the count for which the subscription can be extented.

• type nf_type —Specify the NF type. For this configuration, it should be UDR.

This feature complies with the following standards specifications:

• 3GPP TS 23.501 "System Architecture for the 5G System "

• 3GPP TS 23.502 "Procedures for the 5G System (5GS)"

• 3GPP TS 23.503 "Policy and charging control framework for the 5G System (5GS)"

• 3GPP TS 29.508 "Session Management Event Exposure Service"

• 3GPP TS 29.512 "Session Management Policy Control Service"

• 3GPP TS 29.513 "Policy and Charging Control signalling flows and QoS parameter mapping"

• 3GPP TS 29.519 V15.4.0 "Usage of the Unified Data Repository Service for Policy Data, Application Data and Structured Data for Exposure"

PCF queries the subscriber attributes that are mapped in additional profiles from UDR for the N7 interface. Based on the UDR response, the attributes that are returned are mapped to the subscriber attribute. The allowed services that are returned can be mapped to the services associated with the subscriber.

For information on how to configure the additional profile data, see Setting Up Additional Profile Data.

In Policy Builder, you can access the following filters under Domain > Additional Profile Data > Filter:

• SUPI

• GPSI