IMS Proxy Time Zone Offset Mapping for Charging Accuracy
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Solution Overview
Problem
Current IP Multimedia Subsystem (IMS) systems do not accurately handle time information across multiple time zones, leading to issues with tariff switching and lawful interception, resulting in inaccurate charging and billing problems.
Innovation Solution
A method is introduced where a proxy entity in the core network determines and provides time zone offset information to network elements, allowing for the generation of correct local time stamps for terminals across different time zones, using a mapping table and pre-configured time zone offset information within P-headers of SIP messages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the IMS core network uses a single core network time zone, then the system operation is simplified, but time stamping accuracy for users in different time zones deteriorates
Solution Approach 1:
The patent segments the time zone handling by introducing a mapping table that divides the relationship between core network time and local user times into discrete, manageable entries. Each entry represents a specific time zone offset, allowing the system to select and apply the appropriate offset based on the user's location without complicating the overall core network time structure.
Solution Approach 2:
The patent introduces an intermediary mapping table that mediates between the core network time and local user times. This mapping table acts as a translation layer, converting core network time stamps into accurate local time stamps for users in different time zones without requiring the core network itself to maintain multiple time zones.
2Device complexity
If the IMS network does not implement time zone offset handling, then the network structure remains simple, but charging accuracy for tariff switching deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring the mapping table with all necessary time zone offset information before charging operations begin. This allows the charging system to quickly retrieve and apply the correct time zone offset for tariff switching without performing complex real-time calculations, thereby maintaining charging accuracy while keeping the network structure relatively simple.
3Measurement precision
If the IMS network adds time zone offset determination and propagation mechanisms, then time stamping accuracy improves, but network element complexity increases
Solution Approach 1:
The patent extracts the time zone offset determination logic from individual network elements and consolidates it into a centralized mapping table. This allows network elements to simply retrieve pre-determined offset values from the mapping table based on user identifiers, rather than each element independently determining and maintaining time zone information, thereby limiting the increase in network element complexity.
4Measurement precision
If the system uses post-processing to establish correct time information, then time zone accuracy can be improved, but charging response time deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-configuring the mapping table with all necessary time zone offset information before charging operations begin. This allows the charging system to quickly retrieve and apply the correct time zone offset for tariff switching without performing complex real-time calculations, thereby maintaining charging accuracy while keeping the network structure relatively simple.
Data Source
Figure 1~2
AI summary
A method of handling time information in a communications system (100) comprising: receiving a message at a proxy entity such as a P-CSCF (110, 112, 114) in an IP Multimedia Subsystem (IMS) core network (108); determining a time zone offset between a local time of a terminal and a core network time; providing the time zone offset to a network element (116) in the core network; and generating a time stamp in the network element adjusted to correspond to the local time.