UE Temporary Identity Sync Across 3GPP and Non-3GPP Access

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Solution Overview

Problem

In the existing 5G communication network, UEs in RRC Inactive state with CM-CONNECTED mode experience synchronization issues with mobile identities when transitioning between 3GPP and non-3GPP access, leading to failed paging procedures and incorrect routing due to mismatched temporary identities.

Innovation Solution

The proposed solution involves synchronizing temporary identities by releasing RRC resources and transitioning to RRC Idle state when UE temporary identities change over non-3GPP access, updating NG-RAN with new identities, and using RRC messages to ensure correct paging and routing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the UE maintains RRC Inactive state with CM-CONNECTED mode to preserve connection resources, then resource efficiency is improved, but temporary identity synchronization between UE and NG-RAN deteriorates leading to paging failures

Engineering Contradiction:
Improveresource efficiencyVSAvoidtemporary identity synchronization
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent implements dynamic state transition mechanisms where the UE can switch between RRC Inactive and RRC Idle states based on identity synchronization requirements. When identity desynchronization is detected, the system dynamically transitions to RRC Idle state to perform identity update, then returns to RRC Inactive state normal operation.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the RRC state parameter (from Inactive to Idle) as a control mechanism to resolve identity synchronization issues. This parameter change enables the UE to update its temporary identity and ensures consistency between UE and network, thereby resolving the contradiction between maintaining connection resources and ensuring identity synchronization.

Inventive Principle:
Principle #35Parameter changes

2Adaptability or versatility

If the UE updates temporary identity over non-3GPP access while maintaining RRC Inactive state, then mobility management flexibility is improved, but paging reliability deteriorates due to identity mismatch

Engineering Contradiction:
Improvemobility management flexibilityVSAvoidpaging reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent performs preliminary identity synchronization by transitioning to RRC Idle state before returning to RRC Inactive state. This preliminary action ensures that the temporary identity is updated and synchronized before normal operations resume, preventing paging failures while maintaining mobility flexibility.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The RRC Idle state serves as an intermediary state that mediates between the conflicting requirements of maintaining RRC Inactive state for resource efficiency and updating temporary identity for synchronization. This intermediary state provides a safe transition path to perform identity updates without compromising either resource efficiency or synchronization reliability.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Stability of the object's composition

If the NG-RAN stores old S-TMSI for RRC Inactive UE while AMF assigns new 5G-GUTI, then connection state maintenance is improved, but routing accuracy deteriorates

Engineering Contradiction:
Improveconnection state maintenanceVSAvoidrouting accuracy
Core Design Contradiction:
Stability of the object's compositionVSMeasurement precision

Solution Approach 1:

The patent implements a feedback mechanism where the UE detects identity desynchronization between its stored S-TMSI and the network's S-TMSI, then triggers a state transition to RRC Idle state to perform identity update. This feedback loop ensures that routing accuracy is maintained by synchronizing identities while preserving connection state stability through controlled transitions.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4723698A2A method for synchronizing status of UE in a communication network
Publication Date: 2026.04.08 NEC CORP
  • EP4723698A2 patent drawingFigure 1
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  • EP4723698A2 patent drawingFigure 3

AI summary

The present disclosure relates to synchronizing a temporary identity in the UE and the network when the UE is RRC Inactive state over 3GPP access and temporary identity of the UE is changed over a Non-3GPP access in a scenario when the UE is connected to the same AMF via 3GPP and non-3GPP access.