PCEF Volume-Based Charging in ISWN Handovers
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Solution Overview
Problem
Current online charging protocols for Interworking-WLAN (I-WLAN) do not support volume-based online charging, only allowing time-based authorization, which limits the flexibility and accuracy of charging models, especially during Wi-Fi/LTE handovers where the core network is unaware of the Radio Access Technology (RAT) used for each data flow.
Innovation Solution
Modifying session management messages to notify the Policy and Charging Enforcement Function (PCEF) of RAT changes and adding PCEF volume-based online charging functionality to the Integrated Small Cell and Wi-Fi Network (ISWN), enabling real-time adjustment of charging rules based on the utilized RAT and its initiator, either the User Equipment (UE) or the network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If time-based authorization is used for online charging in I-WLAN, then charging can be implemented, but volume-based charging accuracy and flexibility are limited
Solution Approach 1:
The patent changes the charging parameter from time-based to volume-based by introducing new information elements in session management messages that carry volume metrics (e.g., total volume, remaining volume, threshold volumes). This allows the charging system to transition from authorizing based on time duration to authorizing based on data volume, thereby improving charging accuracy while maintaining flexibility through configurable volume thresholds and multiple charging rules.
2Device complexity
If the core network remains unaware of RAT changes, then network simplicity is maintained, but charging accuracy during handovers deteriorates
Solution Approach 1:
The patent introduces an intermediary mechanism where session management messages act as carriers of RAT change information. The PCEF (Policy and Charging Enforcement Function) receives these messages with embedded information elements indicating RAT changes and initiates appropriate charging actions. This intermediary approach allows the core network to remain relatively simple while still achieving accurate charging by using existing message structures to convey necessary information without requiring complex new signaling protocols.
Solution Approach 2:
The patent implements a feedback mechanism where the PCEF monitors RAT changes through session management messages and provides feedback to the charging system by triggering volume-based charging rule applications. When a RAT change is detected, the PCEF sends feedback to apply appropriate charging rules specific to the new RAT, ensuring accurate charging despite network simplicity. This feedback loop enables the system to adapt charging parameters based on real-time RAT conditions.
3Adaptability or versatility
If volume-based online charging is added to ISWN, then charging flexibility and accuracy improve, but system complexity increases
Solution Approach 1:
The patent introduces dynamic volume-based charging parameters that can be adjusted in real-time based on RAT conditions and user profiles. The system dynamically configures volume thresholds, charging rates, and authorization limits according to the current RAT and service requirements. This dynamic approach allows the system to maintain flexibility and accuracy while managing complexity through adaptive rather than static configurations, enabling the charging system to respond to changing conditions without requiring complex hard-coded rules for every scenario.
Data Source
AI summary
A Policy and Charging Enforcement Function (PCEF) can be aware of whether a UE connects through a cellular or WIFI connection through a gateway. Management messages can be modified to allow the PCEF volume based online charging functionality to remain in the core network (i.e. in the P-GW/PCEF). Session management messaging between the ISWN (ISW-GW) and the core network (P-GW/PCEF) may be modified so that the core network may be notified when the ISWN moves a bearer, or flow, from one RAT to another. Alternately, PCEF volume based online charging functionality can be added to the ISWN. The PCEF of the ISWN can be tasked with performing volume based online charging while the UE is in the ISWN.