MDT Timer Management During Inter-RAT Mobility

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Solution Overview

Problem

In wireless communication systems, mobile devices face issues with endless minimization of drive tests (MDT) measurement logging during radio access technology (RAT) changes, leading to drained power and storage due to continuous logging when transitioning between different RATs like UMTS, LTE, GSM, and CDMA 2000.

Innovation Solution

A method where a mobile device receives an MDT measurement configuration, starts a timer for logging, and keeps it running or restarts it during inter-RAT procedures, ensuring that MDT measurement logging stops only when the timer expires, preventing endless logging across different RATs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the UE stops the MDT timer when performing inter-RAT procedure and releases UTRAN/E-UTRAN specific resources, then the device complexity is reduced, but the MDT measurement logging becomes endless causing power and storage drain

Engineering Contradiction:

ImproveUE resource managementVSAvoidUE power consumption

Core Design Contradiction:

Device complexityVSUse of energy by moving object

Solution Approach 1:

The patent makes the timer behavior dynamic by distinguishing between intra-RAT and inter-RAT procedures. The timer T326/T330 is stopped only for intra-RAT procedures while kept running for inter-RAT procedures, allowing the system to adapt timer behavior based on the specific mobility scenario to prevent endless logging while managing resources efficiently

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent introduces the timer status as an intermediary state that mediates between resource release and continuous logging. By maintaining the timer running during inter-RAT procedures, the system ensures continuous MDT measurement logging without endless loops, while still allowing resource release to occur

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the UE keeps the MDT timer running during inter-RAT procedure, then the MDT measurement logging is continuous and accurate, but the device complexity increases due to timer management across RAT changes

Engineering Contradiction:

ImproveMDT measurement continuityVSAvoidTimer management complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the mobility procedures into intra-RAT and inter-RAT categories, applying different timer management rules to each segment. This segmentation simplifies the overall timer management logic by creating clear, distinct handling paths for different procedure types rather than requiring complex unified logic

Inventive Principle:

Principle #1Segmentation

3Adaptability or versatility

If the UE releases all UTRAN/E-UTRAN specific resources during inter-RAT procedure, then the adaptability to different RATs is improved, but the MDT logging configuration is lost causing endless logging

Engineering Contradiction:

ImproveInter-RAT mobilityVSAvoidMDT logging configuration

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent extracts the timer status information from the RAT-specific resource set and maintains it independently during inter-RAT procedures. By separating the timer management from the UTRAN/E-UTRAN specific resources, the system can release resources for inter-RAT mobility while preserving the timer state needed to control MDT logging duration

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentUS8594671B2Method of handling minimization of drive tests in radio access technology change

Publication Date: 2013.11.26 HTC CORP

AI summary

A method of handling minimization of drive tests, hereafter called MDT, for a mobile device is disclosed. The method comprises receiving a MDT measurement configuration from a first RAT, starting a timer for a MDT measurement logging corresponding to a timer value in the MDT measurement configuration, and keeping the timer running when the mobile device performs an inter-RAT procedure to move from the first RAT to a second RAT.