Offline Charging and Online Charging
Charging is enabled for a session based on the input that is received from the PCF.
For offline charging, the SMF sends Charging Data Request Initial toward the Charging Function (CHF) based on the presence of charging descriptors and refChgData field set in the smPolicyDecision message from the PCF in the SM Policy Control Create response.
On determining if charging is required during initial session establishment or post-session establishment, charging is enabled for the PDU session. Once charging is enabled, SMF sends the Charging Data Request (Initial) Message toward the CHF.
The SMF determines the Volume/Time threshold value either locally or from the Charging Data Response. These values are used to update the Volume/Time threshold IE in URR and to set the reporting trigger accordingly. The measurement method that is used in URR is derived from charging data.
For online charging, the SMF receives the Volume/Time Threshold and Quota values from the CHF. These values are received in the Charging Data Response (Initial) or using a Charging Data Request (Update) during a PDU Session Establishment. The SMF relays these Volume/Time Threshold and quota values to the UPF in the corresponding URR.
If Gy is enabled for an SMF 4G session, the session SMF sends the Credit Control Request (Initial) towards OCS to get the Volume/Time threshold and quota values. SMF relays these values towards to the UPF in the corresponding URR. If the SMF doesn't receive the volume threshold from OCS, the SMF determines the volume threshold from the local configuration.
Note | The threshold values from CHF always override the locally configured values. |
The following table maps the IEs that are shared with the UPF during Create or Update URR during online or offline charging scenarios:
IE | Online | Offline | Derived From (N40) |
Derived From (Gy) |
---|---|---|---|---|
Volume Limit | Yes | Yes | CHF Response or Local Configuration |
OCS Response or Local Configuration |
Time Limit | Yes | Yes | CHF Response or Local Configuration |
OCS Response |
Volume Quota | Yes | No | CHF Response |
OCS Response |
Time Quota | Yes | No | CHF Response |
OCS Response |
Quota Holding Time | Yes | — | CHF Response |
OCS Response |
Monitoring Time | Yes | Yes |
|
OCS Response or Local Configuration |
Reporting Trigger | Yes | Yes | The respective triggers that are set as shown in the following table. |
OCS Response or Local Configuration |
Validity Time |
Yes |
- |
- |
OCS Response or Local Configuration |
The following table lists the reporting triggers and their derived source:
Reporting Trigger | Derived From |
---|---|
Volume Threshold Trigger | If Volume threshold is set |
Time Threshold Trigger | If Time threshold is set |
Volume Quota Trigger | If Quota Exhausted trigger is set from CHF |
Time Quota Trigger | If Quota Exhausted trigger is set from CHF |
Linked Usage Reporting (LIUSA) Trigger | If URR contains Linked URR |