AMF Event Notification Routing During Terminal Migration

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Solution Overview

Problem

In scenarios where a terminal is migrated from a source AMF network element to a target AMF network element, the target AMF network element fails to learn event notifications in a timely manner, leading to delayed processing of subscription events.

Innovation Solution

A method where the event notification network element determines the target subscription network element's callback address information and sends event notifications to the target network element, using identifiers to correlate the event with the terminal, thereby enabling the target subscription to process the event notification of the system to the event notification network element.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the event notification network element continues to use stored subscription information of the source subscription network element, then the subscription information can be maintained consistently, but the target subscription network element cannot receive event notifications in a timely manner

Engineering Contradiction:

Improvesubscription information consistencyVSAvoidevent notification delivery time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The event notification network element performs preliminary actions by storing both the source subscription network element's address and the target subscription network element's address before migration completes. When a notification condition is met, it checks whether the terminal is still served by the source element and directs notifications to the appropriate target element, preventing delivery delays without compromising information consistency

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where the event notification network element receives updates about terminal migration status from the network. This feedback allows it to dynamically adjust where event notifications are sent - continuing to use the source element's address when appropriate or switching to the target element's address when migration is complete, thus resolving the contradiction between consistency and timeliness

Inventive Principle:

Principle #23Feedback

2Device complexity

If the event notification network element sends notifications to the source subscription network element based on stored information, then the notification routing remains simple, but the target subscription network element cannot process events timely

Engineering Contradiction:

Improvenotification routing complexityVSAvoidevent processing speed

Core Design Contradiction:

Device complexityVSProductivity

Solution Approach 1:

The notification routing mechanism transitions from static to dynamic. The event notification network element maintains stored subscription information for simplicity but adds dynamic decision-making capability: it checks current terminal service status and adaptively routes notifications to either the source or target subscription network element, thereby improving event processing speed without significantly increasing system complexity

Inventive Principle:

Principle #15Dynamics

3Reliability

If the target subscription network element does not receive event notifications, then the source subscription network element maintains control, but the migrated terminal cannot be served properly

Engineering Contradiction:

Improveservice continuityVSAvoidevent notification information

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The event notification network element acts as an intermediary that bridges the source and target subscription network elements. It stores subscription information from the source element, monitors terminal migration status, and mediates the delivery of event notifications to the appropriate element. This ensures service continuity for migrated terminals while preventing information loss, as the intermediary guarantees notifications reach the current serving element

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3905739B1Update of subscription to event notification at a network element when terminal migrates from source to target network element

Publication Date: 2025.12.10 HUAWEI TECH CO LTD

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AI summary

Embodiments of this application provide a subscription update method, device, and system, so that a target subscription network element can learn an event notification of a subscription event in a timely manner in a scenario in which a terminal is migrated from a source subscription network element to the target subscription network element. The method includes: determining, by a first event notification network element, that a notification condition of a first subscription event of a first terminal is met; obtaining, by the first event notification network element, first callback address information of a target subscription network element; and sending, by the first event notification network element, a first message to the target subscription network element based on the first callback address information, where the first message carries an identifier of the first terminal and a first event notification of the first subscription event, and the identifier of the first terminal is used to correlate the first event notification with the first terminal.