AMF Re-allocation via RAN Intermediary for Registration Continuity

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Solution Overview

Problem

Current 3GPP specifications lack clarity on how to transfer non-initial UE messages from the initial AMF to the target AMF during AMF re-allocation, leading to service degradation for mobile users.

Innovation Solution

A method involving the AMF receiving a Registration Request message from the UE in a CM-CONNECTED state, where the AMF either reroutes the message directly to a second AMF via the RAN or communicates directly with the second AMF, ensuring seamless registration by including necessary NSSAI and security context information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the initial AMF re-allocates AMF for the UE during registration, then the registration management procedure can be completed, but the transfer of non-initial UE messages from the initial AMF to the target AMF is not clearly defined leading to service degradation

Engineering Contradiction:

Improveregistration management procedureVSAvoidmessage transfer clarity

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The RAN acts as an intermediary to transfer the Registration Request message from the initial AMF to the target AMF. The initial AMF sends the message to the RAN, which then forwards it to the target AMF, establishing a clear message path during AMF re-allocation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The message transfer process is segmented into distinct phases: initial AMF receives the message, determines target AMF, transfers to RAN, and RAN forwards to target AMF. This segmentation clarifies the responsibilities of each network element during AMF re-allocation.

Inventive Principle:

Principle #1Segmentation

2Ease of operation

If the initial AMF transfers the Registration Request message via the RAN to the target AMF, then the message transfer path is established, but the procedure complexity increases due to additional routing steps

Engineering Contradiction:

Improvemessage transfer pathVSAvoidrouting procedure

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The RAN is given the universal capability to handle both initial UE messages and non-initial UE messages during AMF re-allocation. This multi-functionality simplifies the overall system by using an existing network element for the additional transfer role rather than introducing new dedicated components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the AMF re-allocation procedure is implemented without clear specifications, then flexibility in AMF selection is maintained, but service degradation occurs due to undefined message transfer procedures

Engineering Contradiction:

ImproveAMF selection flexibilityVSAvoidservice continuity

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The target AMF provides feedback to the initial AMF about the successful reception of the Registration Request message. This feedback mechanism ensures that the re-allocation procedure is completed successfully and maintains service continuity while preserving AMF selection flexibility.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20240236910A1Method of first access and mobility management function (AMF) apparatus, method of user equipment (UE), first access and mobility management function (AMF) apparatus, and user equipment (UE)

Publication Date: 2024.07.11 NEC CORP

AI summary

[Problem]This disclosure defines a Registration procedure with AMF re-allocation procedure when the UE is in CM-CONNECTED state.[Solution]A method of a first Access and Mobility Management Function (AMF) apparatus includes receiving, from a Radio Access Network (RAN), a Registration Request message of a User Equipment (UE) in CM-CONNECTED state. And the method includes sending the Registration Request message to a second AMF apparatus directly.