LTE-A Carrier Aggregation Measurement Reporting for SCell Selection

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Solution Overview

Problem

In LTE-Advanced mobile communication systems, during Carrier Aggregation (CA) communication, radio base stations face challenges in selecting the Secondary Component Carrier (SCell) without increasing interference, as they lack sufficient information to make optimal choices, leading to suboptimal radio quality and reduced system efficiency.

Innovation Solution

A mobile communication method where the radio base station notifies the mobile station of conditions for measurement reports, including the necessity of reporting measurement results on specific carriers, and the mobile station transmits results from cells that satisfy these conditions, along with cells having optimal quality on the measurement-report target carrier, even if excluded from the condition-satisfied set.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the radio base station eNB#B selects Scell based only on limited measurement results from eNB#A, then the handover process can be completed, but the selected cell may not have optimal radio quality, leading to increased interference and reduced system efficiency

Engineering Contradiction:
Improvehandover completionVSAvoidradio quality
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The mobile station performs measurements on all relevant cells and carriers in advance of the handover decision, storing measurement results for multiple cells including those not currently in the measurement report. This preliminary collection of comprehensive measurement data enables the target base station to make optimal Scell selection after handover, rather than being constrained by limited pre-handover information.

Inventive Principle:
Principle #10Preliminary action

2Loss of information

If the mobile station reports only measurement results from cells satisfying the trigger condition, then the measurement report size is reduced, but the radio base station lacks sufficient information to select the optimal Scell

Engineering Contradiction:
Improvemeasurement information completenessVSAvoidmeasurement report size
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The measurement information is segmented into two parts: (1) a measurement report containing cells satisfying trigger conditions, and (2) additional measurement results for other cells on measurement-report target carriers. This segmentation allows the system to transmit comprehensive measurement data while maintaining structured organization and enabling flexible processing at the base station side.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent adds a new dimension to measurement reporting by including measurement results from cells that do not satisfy trigger conditions, alongside the traditional trigger-based measurements. This multi-dimensional approach provides the base station with comprehensive information across all cells and carriers, enabling optimal Scell selection without being constrained by single-dimension trigger conditions.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

3Reliability

If comprehensive measurement data from all cells is reported, then optimal Scell selection is enabled, but the measurement report size and processing complexity increase

Engineering Contradiction:
ImproveScell selection accuracyVSAvoidmeasurement processing complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies different quality requirements to different parts of the measurement data. Measurement results for cells on measurement-report target carriers are collected with high precision and completeness, while other measurement data can be reported with varying levels of detail. This local quality approach ensures optimal Scell selection capability while managing overall system complexity.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP2566227B1Mobile communication method, radio base station and mobile station
Publication Date: 2015.07.29 NTT DOCOMO INC
  • EP2566227B1 patent drawingFigure 1~3
  • EP2566227B1 patent drawingFigure 4
  • EP2566227B1 patent drawingFigure 5

AI summary

A mobile communication method according to the present invention includes a step of notifying, by a radio base station eNB, a mobile station UE of: a condition under which a measurement report is triggered; a measurement-report target CC having a measurement result that should be reported at the same time when the measurement report is performed; and the maximum number of cells, on the measurement-report target CC, having a measurement result that should be reported, and a step of transmitting, by the mobile station UE, a measurement result of a cell of which the number is equal to or less than the notified maximum number, for each notified measurement-report target CC.