Mobile Station Filtering Coefficient Adjustment for Handover Accuracy

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Solution Overview

Problem

In LTE mobile communication systems, the discontinuous reception control leads to longer measurement intervals for cell handover, resulting in reduced measurement sample numbers and accuracy, which can cause delays in handover decisions and deteriorate communication quality.

Innovation Solution

A mobile station with a filtering unit that adjusts its filtering coefficient based on the reception state, allowing for accurate measurement and timely handover decisions by equalizing the measurement intervals between non-discontinuous and discontinuous reception states.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If discontinuous reception control is applied to reduce power consumption, then power consumption is reduced, but measurement interval becomes longer resulting in reduced measurement accuracy

Engineering Contradiction:
Improvepower consumptionVSAvoidmeasurement accuracy
Core Design Contradiction:
Use of energy by moving objectVSMeasurement precision

Solution Approach 1:

The patent applies dynamics by making the filter coefficient adjustable based on the reception state. The mobile station uses different filter coefficients (k values) depending on whether it is in continuous reception state or discontinuous reception state, allowing the measurement filtering process to adapt dynamically to changing operational conditions and maintain accuracy despite varying measurement intervals

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of the filter coefficient based on the reception state. By modifying the k value in the filtering equation F(n) = (k-1)×F(n-1) + 1×M(n) according to whether the device is in continuous or discontinuous reception, the system compensates for the longer measurement intervals and maintains measurement accuracy without requiring more frequent measurements

Inventive Principle:
Principle #35Parameter changes

2Use of energy by moving object

If measurement frequency is reduced in discontinuous reception state to maximize power saving, then power consumption is reduced, but handover decision timing is delayed

Engineering Contradiction:
Improvepower consumptionVSAvoidhandover decision timing
Core Design Contradiction:
Use of energy by moving objectVSLoss of time

Solution Approach 1:

The patent changes the filter coefficient parameter based on reception state to compensate for reduced measurement frequency. By adjusting k in the filtering equation according to whether the mobile station is in continuous or discontinuous reception state, the system maintains appropriate handover decision timing despite measuring less frequently, effectively compensating for the time loss through parameter adaptation

Inventive Principle:
Principle #35Parameter changes

3Device complexity

If filter coefficient is not adjusted in discontinuous reception state, then device complexity is reduced, but measurement accuracy deteriorates due to longer measurement intervals

Engineering Contradiction:
Improvefiltering process complexityVSAvoidmeasurement accuracy
Core Design Contradiction:
Device complexityVSMeasurement precision

Solution Approach 1:

The patent implements a dynamic filtering process where the mobile station determines its reception state (continuous or discontinuous) and selects the appropriate filter coefficient accordingly. This dynamic adaptation maintains measurement accuracy without requiring complex multiple filtering processes, as the system simply switches between two predefined k values based on the current operational state

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3255920B1Mobile station and mobile communication method
Publication Date: 2019.11.27 NTT DOCOMO INC
  • EP3255920B1 patent drawingFigure 1~2
  • EP3255920B1 patent drawingFigure 3~4
  • EP3255920B1 patent drawingFigure 5

AI summary

A mobile station (UE) according to the present invention includes: a measurement unit (13) configured to measure a radio quality of a serving cell and a peripheral cell; a filtering unit (1%) configured to perform filtering on the measurement result; and a determination unit (15) configured to determine as to whether or not to notify the measurement result after the filtering. The filtering unit (14) configured to adjust a filter coefficient for filtering the measurement: result, when the mobile station (UE) is in a discontinuous reception state.