5G Charging Fallback Using a Fail-Open Function
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Solution Overview
Problem
The Charging Function (CHF) in a 5G Core network is critical for providing charging services but becomes unreachable, leading to interruptions in charging policies and subscriber usage tracking, causing service disruptions.
Innovation Solution
Implementing a Fail-Open Function (FOF) that stores a copy of subscriber information and remains reachable, allowing the 5G Core to continue enforcing policies and tracking usage even when the CHF is offline.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Charging Function (CHF) is implemented as a centralized critical component, then charging services and policy enforcement are improved, but system reliability deteriorates when the CHF becomes unreachable
Solution Approach 1:
The patent creates a local copy of subscriber information and charging data in the Session Management Function (SMF) and User Plane Function (UPF) nodes. This copying mechanism allows these network functions to continue enforcing charging policies and tracking usage even when the centralized CHF becomes unreachable, thereby maintaining service availability without requiring a completely redundant CHF architecture.
Solution Approach 2:
The patent segments the charging functionality by separating the centralized CHF from the distributed network functions. The SMF and UPF are divided into control plane and user plane components, with each having specific roles in charging enforcement. This segmentation allows the system to maintain charging services locally while preserving the centralized management capability.
2Reliability
If the CHF is made highly available through redundancy, then service continuity is improved, but system complexity and resource consumption increase
Solution Approach 1:
The patent implements partial redundancy by storing only essential subscriber information and charging data locally in the SMF and UPF, rather than creating full redundant CHF instances. This partial action approach provides sufficient service continuity for charging enforcement while consuming fewer network resources compared to complete redundancy.
Solution Approach 2:
The patent introduces the SMF as an intermediary between the UPF and the CHF. The SMF acts as a mediator that can enforce charging policies using locally cached information when the CHF is unavailable, and then synchronize with the CHF when it becomes available again. This intermediary approach maintains service continuity without requiring direct CHF redundancy.
3Productivity
If local caching of subscriber information is implemented, then charging policy enforcement continues during CHF outages, but data consistency between local caches and CHF deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the SMF and UPF periodically synchronize their locally cached subscriber information with the centralized CHF. When the CHF becomes available again after an outage, the SMF receives updates and notifications about changes in subscriber information, ensuring that local caches are refreshed to maintain data consistency while minimizing disruption to charging policy enforcement.
Data Source
AI summary
Systems, methods, and devices can be utilized to provide charging function (CHF) fallback in a 5th Generation Core (5GC). An example method is performed by a fail-open function (FOF), and includes receiving, from the CHF, information corresponding to a subscriber of a network. The information is stored in a database. Further, the example method includes receiving, from the CHF or a connected function, a request corresponding to the subscriber. The connected function is a session management function (SMF) and/or a policy control function (PCF). Based on the request, the information stored in the database is at least one of accessed or modified. Based on performing at least one of accessing or modifying the information stored in the database, a response is generated and transmitted to the CHF or the connected function.