LAA Cell Selection Using Channel Clear Ratio for Unlicensed Band
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Solution Overview
Problem
In the LAA system, the conventional cell selection method based on licensed bands can lead to inappropriate cell selection in the unlicensed band, resulting in reduced resource usage due to inadequate consideration of available time resources, which is not accounted for in the conventional index used for cell selection.
Innovation Solution
The introduction of a new index, Channel Clear Ratio (CCR), which reflects the available time resource amount, is used for cell selection in the LAA system to prioritize cells with higher CCR, ensuring appropriate cell selection and improved resource usage by considering the coexistence of other systems in the unlicensed band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the conventional cell selection method based on licensed bands is used in the unlicensed band, then the cell selection process is simple and familiar, but the resource usage is reduced due to inappropriate cell selection
Solution Approach 1:
The patent introduces a new parameter CCR (Channel Clear Ratio) that reflects the available time resource amount in the unlicensed band. This parameter change enables the cell selection to consider LBT results, transforming the selection criterion from simple signal strength to a composite metric that includes channel availability, thereby resolving the contradiction between simplicity and resource usage efficiency
2Reliability
If LBT is performed in the unlicensed band, then interference with other systems is avoided, but the available time resources become variable and difficult to predict
Solution Approach 1:
The patent implements a feedback mechanism where LBT results are fed back into the cell selection process. The CCR parameter is calculated based on LBT outcomes and used to adjust cell selection decisions, creating a closed-loop system that adapts to the variable time resources caused by LBT, thus resolving the contradiction between interference avoidance and time resource predictability
Data Source
AI summary
In order to prevent, in an LAA system supporting LBT, reduction in resource usage of the system, the present invention provides a radio base station that communicates with a user terminal capable of using a licensed band and unlicensed band. The radio base station comprises: an obtaining section that obtains information about an available time resource amount that is determined based on a result of LBT (Listen Before Talk) in the unlicensed band; and a control section that controls communication with the user terminal in the unlicensed band based on the information about the available time resource amount.