LTE TAU Suppression for Dual-SIM Call Continuity

Solution Overview

Problem

In dual-SIM devices with a single transmitter, LTE tracking area updates (TAUs) can interrupt active communications on the second SIM due to prioritization of LTE uplink transmissions, leading to voice call drops, increased power consumption, and signaling packet loss.

Innovation Solution

The UE prioritizes the current LTE cell frequency and suppresses TAU procedures until the cell selection reception level or quality falls below a certain threshold, ensuring uninterrupted active communications by maintaining the current cell connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE performs LTE tracking area update (TAU) procedures when moving to a new tracking area, then the UE can maintain proper network registration and receive paging, but the active communication on the second SIM is interrupted due to transmitter prioritization

Engineering Contradiction:

Improvenetwork registration reliabilityVSAvoidactive communication continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent implements dynamic priority adjustment of the current LTE cell frequency based on the state of active communication on the second SIM. When active communication is detected, the system dynamically elevates the priority of the current frequency to prevent TAU procedures, thereby adaptively resolving the contradiction between network registration reliability and communication continuity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary detection of active communication states on the second SIM before initiating TAU procedures. By checking for ongoing voice calls or data transmissions in advance, the system can prevent TAU initiation that would cause interruptions, thus maintaining communication continuity while preserving network registration through alternative mechanisms

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the UE frequently performs TAU procedures during mobility, then the UE can maintain accurate location registration, but power consumption increases due to repeated uplink transmissions

Engineering Contradiction:

Improvelocation registration accuracyVSAvoidpower consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent implements dynamic priority adjustment of the current LTE cell frequency based on the state of active communication on the second SIM. When active communication is detected, the system dynamically elevates the priority of the current frequency to prevent TAU procedures, thereby adaptively resolving the contradiction between network registration reliability and communication continuity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the priority parameter of the current frequency dynamically based on communication state. By adjusting this parameter, the system reduces the frequency of TAU procedures and associated uplink transmissions, thereby lowering power consumption while maintaining adequate location registration through other mechanisms

Inventive Principle:

Principle #35Parameter changes

3Reliability

If the UE prioritizes TAU procedures over active communication, then the UE can ensure successful paging reception, but signaling packet loss occurs leading to call drops

Engineering Contradiction:

Improvepaging reception success rateVSAvoidsignaling packet loss

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The patent implements dynamic priority adjustment of the current LTE cell frequency based on the state of active communication on the second SIM. When active communication is detected, the system dynamically elevates the priority of the current frequency to prevent TAU procedures, thereby adaptively resolving the contradiction between network registration reliability and communication continuity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary detection of active communication states on the second SIM before initiating TAU procedures. By checking for ongoing voice calls or data transmissions in advance, the system can prevent TAU initiation that would cause interruptions, thus maintaining communication continuity while preserving network registration through alternative mechanisms

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10057870B2Communication device and a method for operating a communication device

Publication Date: 2018.08.21 APPLE INC

AI summary

A method and device for decreasing the frequency of tracking area update (TAU) procedures triggered by cell reselections in LTE idle mode without sacrificing paging reception success rate consisting of identifying a frequency of a camped cell in LTE idle mode of a first SIM; assigning the current frequency a highest priority irrespective of the system information blocks (SIBs) broadcast by the network; and remaining on the current frequency until: a cell selection reception level value of the camped cell is less than a first predetermined threshold value or a cell selection quality value of the camped cell is less than a second predetermined threshold value.