PCRF Intermediary for SGSN Change Detection in Online Charging
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Solution Overview
Problem
In the Evolved Packet System (EPS), the Packet Data Network Gateway (P-GW) is unaware of changes in the Serving General Radio Packet Service support node (SGSN) during online charging, preventing re-requesting of credit from the Online Charging System (OCS).
Innovation Solution
A method where the Policy and Charging Enforcement Function (PCEF) entity provides a SGSN change event trigger to the Policy and Charging Rules Function (PCRF) entity, which subscribes to the Bearer Binding and Event Report Function (BBERF) entity to detect and report SGSN changes, allowing the P-GW to re-request credit from the OCS.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the P-GW uses PMIP protocol in the S5 interface, then the bearer establishment and QoS control are improved, but the P-GW becomes unaware of SGSN changes and cannot re-request credit from OCS
Solution Approach 1:
The PCRF entity acts as an intermediary between the P-GW and the BBERF entity. It receives SGSN change information from the BBERF and forwards this information to the P-GW, enabling the P-GW to become aware of SGSN changes without directly monitoring them. This intermediary mechanism resolves the information loss problem while maintaining the PMIP protocol's bearer control capabilities.
Solution Approach 2:
The system establishes a feedback loop where the BBERF entity notifies the PCRF entity about SGSN changes, which then notifies the P-GW. This feedback mechanism ensures that the P-GW is continuously informed of network changes, allowing it to re-request credit from the OCS when necessary, thus improving credit control management reliability.
2Device complexity
If the P-GW is unaware of SGSN changes, then the network architecture remains simple, but credit re-authorization cannot be triggered
Solution Approach 1:
The PCRF entity is pre-configured with the ability to subscribe to SGSN change events from the BBERF entity. This preliminary setup ensures that when SGSN changes occur, the system is already prepared to automatically trigger credit re-authorization procedures, improving efficiency without requiring complex real-time monitoring architecture.
3Reliability
If the P-GW continuously monitors SGSN changes, then credit control reliability is improved, but the system complexity and processing overhead increase
Solution Approach 1:
Instead of having the P-GW directly monitor SGSN changes, the PCRF entity serves as an intermediary that subscribes to changes from the BBERF and relays this information to the P-GW. This approach improves reliability while avoiding the complexity of direct continuous monitoring by the P-GW.
Solution Approach 2:
The BBERF entity automatically detects and reports SGSN changes to the PCRF entity without requiring the P-GW to actively query or monitor. The system uses self-service mechanisms where network changes are automatically propagated through the established notification channels, reducing processing overhead while maintaining reliability.
Data Source
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AI summary
The present invention discloses a method and system for acquiring an address of a Serving General Radio Packet Service support node (SGSN). The method comprises: a Policy and Charging Enforcement Function (PCEF) entity providing a SGSN change event trigger to a Policy and Charging Rules Function (PCRF) entity; and the PCRF entity reporting a SGSN change event and a new address of the SGSN to the PCEF entity after receiving the SGSN change event trigger. The method solves the problem that credit control management cannot be carried out for different general radio packet service support nodes during online charging.