Cell-Type-Specific Measurement Criteria for LTE Handover Distribution
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Solution Overview
Problem
In LTE-Advanced systems, the introduction of DL New Carrier Type (NCT) as a secondary carrier leads to uneven distribution of radio terminals capable and incapable of using NTCC, causing handover and traffic concentration issues due to inappropriate configuration of Legacy PCell and NTCC PCell ratios, which are difficult to manage due to varying user capabilities and locations.
Innovation Solution
The radio terminal is instructed to perform terminal measurement reports considering the type of cell or carrier, using specific measurement report criteria such as offset values, decision thresholds, and trigger periods to appropriately distribute handover targets and secondary cells, allowing the radio base station to manage cell usage effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If DL New Carrier Type (NCT) is introduced as a secondary carrier to improve downlink throughput and cell capacity, then radio resources for transmitting downlink user data are increased, but handover and traffic concentration occurs on specific cells due to uneven distribution of radio terminals capable of using NTCC
Solution Approach 1:
The invention changes the measurement report criteria parameters (offset values, decision thresholds, trigger periods) based on the cell type (Legacy or NTCC) to control handover behavior. By adjusting these parameters dynamically, the system achieves both high downlink throughput through NTCC usage and balanced handover distribution across cell types.
Solution Approach 2:
The invention applies different measurement report criteria to different cell types (Legacy PCell vs. NTCC PCell). Each cell type has customized offset values, decision thresholds, and trigger periods tailored to its characteristics, enabling localized optimization of handover distribution while maintaining overall system productivity.
2Device complexity
If measurement report criteria are configured without considering cell type to simplify network management, then configuration complexity is reduced, but handover targets and secondary cells become concentrated on specific cell types
Solution Approach 1:
The invention introduces cell-type-specific parameter sets for measurement report criteria. The base station configures different offset values, decision thresholds, and trigger periods based on whether the cell is Legacy or NTCC type. This parameter differentiation enables effective handover distribution without requiring complex manual configuration management.
3Ease of operation
If ratio of Legacy PCell and NTCC PCell is adjusted to balance handover distribution, then handover concentration is reduced, but the ratio becomes difficult to manage due to varying user capabilities and locations
Solution Approach 1:
Instead of manually adjusting cell ratios, the invention changes the measurement report criteria parameters (offset values, decision thresholds, trigger periods) to indirectly control handover distribution. This parameter-based approach achieves balanced handover distribution across different cell types without requiring complex ratio management, as the parameters automatically adapt to user capabilities and locations.
Data Source
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AI summary
The present invention is a radio communication system in which a radio station and a radio terminal communicate with each other. The radio communication system has a control means with which at least one of the radio stations controls a plurality of types of cells by using one radio access technology, a recognition means with which the radio terminal recognizes the types of the cells, and a measurement report means with which the radio terminal performs a report of measurement results based on measurement report criteria according to the types of the cells.