PCF Policy Association Updates During 5G AMF Reselection

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Solution Overview

Problem

In 5G systems, during AMF reselection, the old PCF needs to delete the policy association with the old AMF, leading to resource wastage and inefficiency in the policy control network element.

Innovation Solution

The proposed solution involves the new AMF requesting the old PCF to update the policy association information to the new AMF without deleting the existing association, thereby reducing resource overheads by avoiding the need for re-establishment and interaction with the UDR.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the old PCF deletes the policy association with the old AMF during AMF reselection, then the policy association can be re-established with the new AMF, but resource overheads of the PCF network element increase due to deletion and re-establishment operations

Engineering Contradiction:

Improvepolicy association validityVSAvoidresource overheads of PCF

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies preliminary action by having the new AMF proactively request the old PCF to update the policy association information before the old AMF releases the association. This allows the PCF to maintain the association without deletion, avoiding the resource overhead of delete and re-establish operations while ensuring the association remains valid for the new AMF

Inventive Principle:

Principle #10Preliminary action

2Adaptability or versatility

If the old PCF deletes the policy association with the old AMF, then the new AMF can establish a fresh association, but the process requires interaction with the UDR which increases complexity and time consumption

Engineering Contradiction:

Improvepolicy association flexibilityVSAvoidinteraction processes with UDR

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent extracts the policy association information from the UDR interaction chain by allowing the new AMF to directly request updates from the old PCF. This eliminates the need for the PCF to delete and re-query the UDR, reducing process complexity and time consumption while maintaining the flexibility of policy association management

Inventive Principle:

Principle #2Taking out (Extraction)

3Loss of energy

If the old PCF maintains the policy association without deletion, then resource overheads are reduced, but the association information may become incorrect for the new AMF

Engineering Contradiction:

Improveresource overheads of PCFVSAvoidpolicy association accuracy

Core Design Contradiction:

Loss of energyVSLoss of information

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback through the update request mechanism where the new AMF provides its identification information to the old PCF, which then updates the association information accordingly. This feedback loop ensures the policy association remains accurate and current for the new AMF while avoiding resource wastage

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP3745774B1Policy control method, device and system

Publication Date: 2025.10.08 HUAWEI TECH CO LTD

Figure 1(a)~1(b)
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AI summary

A policy control method, an apparatus, and a system are provided. The method includes: after receiving, by a policy control network element, an update request message from a first mobility management network element, updating, by the policy control network element according to the update request message, information about a second mobility management network element in information of a policy association corresponding to a terminal that is stored in the policy control network element to information about the first mobility management network element, where the information about the first mobility management network element is carried in the update request message. The policy control network element does not need to re-establish a policy association with the first mobility management network element after deleting the information about the second mobility management network element in the information of the policy association corresponding to the terminal. Instead, the policy control network directly updates the information about the second mobility management network element in the information of the policy association corresponding to the terminal to the information about the first mobility management network element. Therefore, resource overheads for policy control can be reduced.