Roaming UE Instant Registration via LOCI Update

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Solution Overview

Problem

Existing methods for seamless and instant registration of a roaming UE onto a preferred visited network are unclear and inefficient, as previous solutions do not guarantee registration on all Mobile Equipment (ME) when updating the LOCI file with a preferred PLMN ID, especially when using REFRESH commands like REFRESH—File Change Notification or REFRESH—UICC Reset, leading to potential network selection failures and higher roaming costs.

Innovation Solution

Updating only the MCCMNC content in the LOCI file with the preferred PLMN ID while keeping the TMSI and Location update status intact, followed by a REFRESH—3G Session Reset command, ensures immediate registration within seconds, and can be implemented using either an OTA solution or a SIM Toolkit application.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the LOCI file is updated with the PLMN ID of the preferred visited network using previous methods, then the PLMN ID is updated, but seamless and instant registration does not work for all MEs

Engineering Contradiction:

ImprovePLMN ID update accuracyVSAvoidregistration success rate

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent changes specific parameters in the LOCI file (bytes 1-4 for TMSI, byte 5 for Location update status) to specific values (FF FF FF FF and 00 respectively) that trigger the MM Restart procedure, ensuring reliable instant registration across all ME implementations

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses the REFRESH command with File Change Notification to provide feedback to the ME about the LOCI file update, triggering the registration process. The combination of specific byte updates and the REFRESH command creates a reliable feedback mechanism that ensures all MEs perform the registration procedure

Inventive Principle:

Principle #23Feedback

2Productivity

If REFRESH—UICC Reset is used after LOCI file update, then the LOCI file is refreshed, but the ME performs a powercycle which gives the perception of malfunction

Engineering Contradiction:

Improveregistration speedVSAvoiduser perception of system stability

Core Design Contradiction:

ProductivityVSEase of operation

Solution Approach 1:

The patent extracts the MM Restart procedure from the full UICC Reset process by specifically updating only the necessary bytes in the LOCI file and using a targeted REFRESH command, avoiding the need for a complete powercycle while still achieving instant registration

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent uses the MM Restart procedure as an intermediary mechanism that achieves the registration effect without requiring a full UICC Reset. The specific byte updates in LOCI act as an intermediary trigger that initiates registration without the disruptive powercycle

Inventive Principle:

Principle #24Intermediary (Mediator)

3Productivity

If REFRESH—3G Session Reset is used, then network connection is re-initialized, but it is not guaranteed that all MEs will perform new network selection attempt

Engineering Contradiction:

Improvenetwork re-initialization speedVSAvoidnetwork selection execution guarantee

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent performs preliminary updates to the LOCI file bytes (TMSI to FF FF FF FF and Location update status to 00) before issuing the REFRESH command, ensuring that when the ME restarts, it immediately performs network selection with the updated PLMN ID rather than requiring additional conditions

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS9026107B2Method for instant registration of a roaming UE onto a preferred VPLMN from a non-preferred VPLMN

Publication Date: 2015.05.05 TELUS CORP

AI summary

A User Equipment (UE) that was registered on a non-preferred network operator may be forced to register immediately and seamlessly onto another available more preferred network operator by updating the EF_LOCI in the UICC with the MCCMNC (i.e. PLMN ID) of the preferred network operator and then sending the REFRESH—3G Session Reset command to the Mobile Equipment (ME).