UE Registration Trigger for PLMN Change in RRC Inactive State

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Solution Overview

Problem

The issue of mismatch between user equipment (UE) and network entities regarding the selected public land mobile network (PLMN) during registration procedures in 5G communication networks, particularly in RRC inactive states, leads to failures in deregistration and authentication processes.

Innovation Solution

A method for UE to automatically trigger a registration procedure when moving from one PLMN to another within the same registration area, ensuring synchronization by sending a registration request message to the network, even in RRC inactive state.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE moves to a new cell in a different PLMN within the same registration area while in RRC inactive state, then the UE can camp on the new PLMN, but the network entity remains unaware of the PLMN change causing mismatch

Engineering Contradiction:
ImproveUE ability to camp on different PLMNsVSAvoidNetwork entity awareness of UE's current PLMN
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The network entity proactively sends a registration request to the UE when it needs to initiate a procedure. This preliminary action allows the network to trigger a PLMN update before proceeding with procedures like deregistration or authentication, ensuring the UE provides its current PLMN information.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The UE responds to the network's registration request by providing feedback about its current PLMN through a registration accept message. This feedback mechanism ensures the network entity receives updated PLMN information, resolving the awareness mismatch.

Inventive Principle:
Principle #23Feedback

2Productivity

If the network entity initiates a deregistration or authentication procedure without knowing the current PLMN, then the procedure can be initiated, but the procedure fails due to PLMN mismatch

Engineering Contradiction:
ImproveNetwork entity ability to initiate proceduresVSAvoidSuccess of network-initiated procedures
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

Before initiating deregistration or authentication procedures, the network entity first sends a registration request to obtain current PLMN information. This preliminary action ensures the network has accurate PLMN data before proceeding with the actual procedure, preventing failures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent prevents the harmful effect of PLMN mismatch by proactively obtaining updated PLMN information through a registration request before initiating procedures that would otherwise fail due to outdated PLMN data.

Inventive Principle:
Principle #9Preliminary anti-action

3Loss of energy

If the UE does not trigger registration procedure when moving within registration area, then signaling overhead is reduced, but PLMN synchronization is lost

Engineering Contradiction:
ImproveSignaling overheadVSAvoidPLMN synchronization information
Core Design Contradiction:
Loss of energyVSLoss of information

Solution Approach 1:

The network entity acts as an intermediary by initiating a registration request when it needs to perform procedures. This intermediary approach allows the network to obtain updated PLMN information without requiring the UE to proactively trigger registration, balancing signaling overhead with information accuracy.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP3845015B1Method and UE for triggering registration procedure within registration area of wireless communication network
Publication Date: 2026.02.25 SAMSUNG ELECTRONICS CO LTD
  • EP3845015B1 patent drawingFigure 1
  • EP3845015B1 patent drawingFigure 2~3
  • EP3845015B1 patent drawingFigure 4~5

AI summary

A method for triggering a registration procedure by a UE within a registration area of a wireless communication network is provided. The method includes receiving a TAI list in a registration accept message while performing a first registration procedure with the wireless communication network and determining when the UE is moved from a first cell in a first TAI belonging to a first PLMN to a second cell in a second TAI belonging to a second PLMN, determining that the UE is in an RRC inactive state, and automatically triggering a second registration procedure with the wireless communication network, in response to determining that the UE is moved from first cell in first TAI belonging to first PLMN to second cell in second TAI belonging to second PLMN.