How it Works
The SMF integrates the CHF and PCF functions based on the following information:
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Policy control request triggers, which are received in the SM policy decision during PDU session establishment or PCF or UE-initiated modification.
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Session-level or rating-group-level charging triggers, which are received during PDU session establishment or in response to SMF-initiated Charging Update Request or CHF-initiated Charging Update Notify Request.
The SMF supports the following access-side information to detect the PCF and CHF triggers. The SMF sends the trigger information to the CHF and PCF during the N2-based handover.
Access Side Information |
CHF Triggers |
PCF Triggers |
---|---|---|
UserLocation |
USER_LOCATION_CHANGE |
SAREA_CH |
UeTimeZone |
UE_TIMEZONE_CHANGE |
SAREA_CH |
ServingNetwork |
PLMN_CHANGE |
PLMN_CH |
TargetServingNfId |
SERVING_NODE_CHANGE |
For a change in the subscriber location, the SMF sends USER_LOCATION_CHANGE trigger towards CHF and SAREA_CH trigger towards PCF.
The SMF generates the usage report whenever a change in the subscriber location is detected in the following messages:
-
Delete Bearer Command
-
Delete Bearer Response
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Modify Bearer Request
For example, when a Delete Bearer Command is received with a new ULI, a CDR event is triggered with new ULI. If PCF or CHF has armed notification for ULI modifications, the SMF sends a notification to the PCF and CHF respectively.
This feature is compliant with the 3GPP TS 32.291, version 15.4.0.