IMS Charging ID Correlation via Orig-ICID Nesting
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Solution Overview
Problem
In IP Multimedia Subsystem (IMS) networks, correlating charging information across multiple retargeted SIP messages is challenging due to the lack of access to the original Charging Identifier (ICID) by network entities that perform retargeting functions, leading to difficulties in correlating charging data and network tracing.
Innovation Solution
Incorporating an orig-icid parameter in retargeted SIP messages that references the original ICID, allowing each retargeted message to include a reference to the previous ICID, enabling correlation of charging information across all call legs and facilitating network tracing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a new ICID is generated for each retargeted SIP message, then charging information can be tracked for each call leg, but correlation of charging data across multiple retargeting operations becomes difficult
Solution Approach 1:
The patent embeds the original ICID within each retargeted SIP message by inserting it into the P-Charging-Vector header. This nesting approach allows the original ICID to be carried through multiple retargeting operations, enabling correlation of charging data across call legs without requiring complex external tracking mechanisms.
Solution Approach 2:
The P-Charging-Vector header acts as an intermediary carrier that transports the original ICID through the retargeting process. Instead of directly maintaining ICID relationships between call legs, the system uses this header field as a mediator to pass correlation information along the message path.
2Productivity
If ICID is changed during retargeting, then each call leg can be independently identified, but network tracing capabilities deteriorate
Solution Approach 1:
The patent performs preliminary action by extracting and preserving the original ICID before the retargeting process alters the message flow. By proactively capturing the original ICID and embedding it in the P-Charging-Vector header of the retargeted message, the system ensures tracing information is retained despite ICID changes.
Solution Approach 2:
The system creates a copy of the original ICID and embeds it within the retargeted SIP message's P-Charging-Vector header. This copying mechanism allows the original identifier to be preserved and forwarded alongside the new ICID, enabling both independent call leg identification and continuous network tracing.
3Measurement precision
If retargeted messages include reference to original ICID, then charging information correlation improves, but message header complexity increases
Solution Approach 1:
The P-Charging-Vector header field serves multiple functions: it carries the original ICID for correlation purposes, maintains compatibility with existing charging mechanisms, and provides a standardized location for ICID transmission. This multi-functionality approach avoids creating entirely new header structures, thereby limiting complexity increase.
Data Source
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AI summary
In a method of correlating information relating to messages in a SIP session, a first SIP message that includes a first IMS Charging Identifier, ICID, is received. The first SIP message is retargeted by generating a second SIP message that includes a second ICID. A reference to the first ICID is i nserted into the second S I P message. Information relating to the first SI P message is correlated with information relating to the second SIP message based on the first ICID and the reference to the first ICID in the second SIP message.