IMS Proxy Call Session Control Function Volume Policing
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Solution Overview
Problem
Current IP Multimedia Subsystem (IMS) charging systems are vulnerable to fraud due to lack of volume policing mechanisms, leading to unintended data transfers and complex inter-operator agreements, as they primarily rely on bandwidth policing and bearers for charging, which are not under direct IMS control.
Innovation Solution
Implementing a Proxy Call Session Control Function that determines and enforces thresholds for user traffic within the IMS core network, allowing for volume policing without additional media proxies, by setting data volume or time thresholds based on service nature and dynamic session data, and notifying the policy decision function to authorize or terminate sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bandwidth policing and bearer charging are used for IMS charging, then charging infrastructure can be established, but volume policing mechanisms are lacking leading to fraud vulnerability
Solution Approach 1:
The patent introduces a Policy Decision Function (PDF) as an intermediary between the IMS core and the charging infrastructure. The PDF receives service information from the IMS, determines appropriate data volume thresholds, and communicates these to the Policy Enforcement Function (PEF). This intermediary layer enables volume policing without requiring direct IMS control over bearer charging, thus maintaining charging accuracy while reducing fraud risk.
Solution Approach 2:
The system performs preliminary actions by determining data volume thresholds before actual data transfer occurs. The PDF calculates appropriate thresholds based on service type and user subscription, then pre-configures these limits in the PEF. This preliminary threshold setting enables proactive fraud prevention rather than reactive detection, allowing the system to block excessive data transfers before they occur.
2Ease of operation
If additional media proxies are deployed for volume policing, then traffic control capability is improved, but system complexity increases
Solution Approach 1:
The patent makes the existing Policy Enforcement Function (PEF) multi-functional by enabling it to perform both bandwidth policing and data volume policing. Instead of introducing dedicated media proxies, the PEF is enhanced to enforce volume thresholds determined by the PDF. This universal approach provides comprehensive traffic control capability while avoiding the complexity of additional specialized components.
Solution Approach 2:
The patent extracts the volume policing logic from the IMS core and places it in the PDF, which then communicates with the existing PEF. This extraction allows volume control functionality to be added without modifying the IMS core or introducing new media proxies. The separation of concerns maintains system simplicity while achieving enhanced traffic control capability.
3Productivity
If bearer charging is used for IMS services, then charging can be implemented, but dependency on non-IMS controlled elements increases
Solution Approach 1:
The patent adds a new dimension to charging control by introducing service-specific data volume thresholds alongside traditional bearer-based charging. The PDF determines volume limits based on service type and user subscription, creating a layered charging model. This additional dimension of control allows IMS to maintain independence while still utilizing bearer charging infrastructure, as volume policing operates at the application layer independent of bearer management.
Data Source
AI summary
Apparatus configured to implement a Proxy Call Session Control Function for use within an IP Multimedia Subsystem core network. The apparatus comprises a receiver for receiving a session initiation request in respect of an IP Multimedia Subsystem service, and a threshold determiner for determining a threshold applicable to user traffic associated with said service. The apparatus further comprises a sender for sending a session authorisation request to a policy decision function, the request including said threshold and a service data flow identifier identifying the user plane flow for said session.