UE Registration via NAS Security Context Deletion

Solution Overview

Problem

In a 5G mobile communication system, user equipment (UE) fails to register due to the target Access and Mobility Management Function (AMF) not having an NAS security context, leading to authentication request messages being discarded by the UE.

Innovation Solution

The initial AMF sends indication information to the UE to delete or discard the existing NAS security context, allowing the UE to process authentication requests without security protection during AMF reallocation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target AMF sends an authentication request message without security protection to the UE during AMF reallocation, then the UE can process the authentication request, but the UE discards the message because it expects security protection based on the existing NAS security context

Engineering Contradiction:

Improveauthentication success rateVSAvoidsecurity context management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The initial AMF performs preliminary action by deleting or deactivating the NAS security context before initiating AMF reallocation. This preliminary action ensures that when the target AMF sends authentication requests without security protection, the UE will process them correctly without discarding them due to expecting security protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The initial AMF acts as an intermediary that coordinates between the UE and target AMF during reallocation. It sends indication information to the UE about the upcoming reallocation and security context deletion, enabling the UE to properly handle authentication requests from the target AMF that lack security protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the UE maintains the existing NAS security context during AMF reallocation, then security is preserved, but the UE fails to process authentication requests from the target AMF without security protection

Engineering Contradiction:

Improveregistration completion rateVSAvoidauthentication request rejection

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The initial AMF performs preliminary action by deleting or deactivating the NAS security context before initiating AMF reallocation. This preliminary action ensures that when the target AMF sends authentication requests without security protection, the UE will process them correctly without discarding them due to expecting security protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The initial AMF provides feedback to the UE through indication information about the upcoming AMF reallocation and security context deletion. This feedback enables the UE to adjust its behavior and process authentication requests from the target AMF correctly, preventing rejection of legitimate authentication messages.

Inventive Principle:

Principle #23Feedback

3Adaptability or versatility

If the initial AMF performs AMF reallocation via (R)AN, then the UE can be served by a different AMF, but the UE fails to register due to security context issues

Engineering Contradiction:

ImproveAMF flexibilityVSAvoidregistration success rate

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The initial AMF performs preliminary action by deleting or deactivating the NAS security context before initiating AMF reallocation. This preliminary action ensures that when the target AMF sends authentication requests without security protection, the UE will process them correctly without discarding them due to expecting security protection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The initial AMF acts as an intermediary that coordinates between the UE and target AMF during reallocation. It sends indication information to the UE about the upcoming reallocation and security context deletion, enabling the UE to properly handle authentication requests from the target AMF that lack security protection.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS12309734B2Registration method and apparatus for registering user equipment

Publication Date: 2025.05.20 HUAWEI TECH CO LTD

AI summary

Embodiments of this application relate to a registration method and apparatus to ensure that user equipment does not discard and processes a received authentication request message sent by a target AMF. In the registration method, an initial AMF sends indication information to the UE, or the target AMF sends, to the UE, the authentication request message that includes indication information, where the indication information is used to indicate the UE to delete an NAS security context. The UE deletes the NAS security context, processes the received authentication request message, and sends an authentication response message to the target AMF. Alternatively, the UE directly processes a received authentication request message without security protection, and sends an authentication response message to the target AMF.