User Equipment Attach Procedure via RAT and PLMN Reselection

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Solution Overview

Problem

Existing methods for user equipment to perform attach procedures when roaming on public land mobile networks often result in attach reject messages due to insufficient signal quality, preventing the provision of packet-switched services even when better signal quality options are available.

Innovation Solution

Implementing a method where user equipment retries by reselecting alternative radio access technologies (RATs) and public land mobile networks (PLMNs) upon receiving reject messages, following specific reject causes, to increase the success rate of packet-switched service attachments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If user equipment performs attach procedure using first RAT with best signal quality, then signal quality is improved, but attach success rate deteriorates when PLMN only provides services via second RAT

Engineering Contradiction:

Improvesignal qualityVSAvoidattach success rate

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

The user equipment dynamically switches between different RATs based on attach procedure outcomes. When the first attach procedure using the first RAT fails, the system transitions to attempting attachment via the second RAT, adapting its behavior in response to network conditions and reject messages

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the RAT parameter from the first RAT to the second RAT when the initial attach procedure fails. This parameter change allows the user equipment to attempt attachment through alternative access technologies when the primary choice is rejected

Inventive Principle:

Principle #35Parameter changes

2Illumination intensity

If user equipment camps on first PLMN using first RAT, then signal quality is optimized, but service availability deteriorates when attach is rejected

Engineering Contradiction:

Improvesignal qualityVSAvoidservice availability

Core Design Contradiction:

Illumination intensityVSAdaptability or versatility

Solution Approach 1:

The user equipment dynamically adjusts its camping behavior by switching from the first RAT to the second RAT when attach procedures fail. This dynamic adaptation ensures continued service availability by responding to network rejection messages with alternative attachment attempts

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system prepares multiple attach procedures in advance (first attach procedure via first RAT, second attach procedure via second RAT) so that when the primary option is rejected, the alternative is already ready to execute, minimizing service interruption

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS8706111B2Method of performing attach procedures

Publication Date: 2014.04.22 ACER INC

AI summary

A user equipment is configured to perform an attach procedure by camping on a specific PLMN using a specific RAT. When receiving an attach reject due to a specific reject cause, the user equipment is configured to perform the attach procedure by camping on the specific PLMN using another RATs. When the attach procedure after RAT reselection fails, the user equipment is configured to perform the attach procedure by camping on another PLMN using one or multiple RATs.