Usage Monitoring Data Modification
Following are the available data modification scenarios for the usage monitoring over PCF.
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If the PCF needs to remove the threshold level for one or multiple monitoring keys, the PCF provides the corresponding attribute with the NULL value to the corresponding usage monitoring control instance.
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When the PCF receives the accumulated usage in the HTTP POST message, the PCF communicates to SMF whether the usage monitoring continues for the following usage monitoring control instance:
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If the monitoring continues for the specific levels, the PCF provides the new thresholds for the levels in the response of the HTTP POST message. This message includes the existing attributes, such as "volumeThreshold", "volumeThresholdUplink", and "volumeThresholdDownlink".
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If the PCF stops monitoring for the specific levels, the PCF doesn't include an updated threshold in the response of the HTTP POST message for the stopped levels. It implies that PCF doesn't include the corresponding attributes in the entry of the "umDecs" attribute. These attributes are "volumeThreshold", "volumeThresholdUplink", "volumeThresholdDownlink", "timeThreshold", "nextVolThreshold", "nextVolThresholdUplink", "nextVolThresholdDownlink", and "nextTimeThreshold".
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If the PCF stops the monitoring for the usage monitoring control instance, the PCF doesn't include any thresholds of the usage monitoring control instance in the response of the HTTP POST message. In addition, the PCF doesn't remove the reference of the usage monitoring control instance from the dynamic PCC rule or session rule.
Based on the following scenarios, SMF sends the PFCP Session Modification Request to PCF:
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In case of modification in the existing thresholds, SMF updates the URR with the new thresholds and initiates Update URR towards UPF in the PFCP Session Modification Request.
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In case of stopped monitoring for the usage monitoring control instance, SMF removes the URR and initiates Remove URR toward UPF in the PFCP Session Modification Request.
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In case of new usage monitoring control instance, SMF creates a new URR with the thresholds. SMF also associates the URR to the corresponding PDRs and initiates Create URR along with Update PDR toward UPF in the PFCP Session Modification Request.