User Terminal Interference Measurement in Unlicensed Bands
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Solution Overview
Problem
In next-generation mobile communication systems, accurately measuring interference in unlicensed bands is challenging due to the absence of periodic Discovery Reference Signals, making it difficult to improve spectral efficiency in communication using these bands.
Innovation Solution
A user terminal measures interference in unlicensed bands based on measurement timing configuration information from a licensed band radio base station, allowing the radio base station to select an optimal unlicensed band for connection, employing an RSSI-like measurement method similar to that used in licensed bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If RSSI-based measurement method used in licensed bands is applied to unlicensed bands, then measurement simplicity is improved, but measurement precision deteriorates due to absence of periodic reference signals
Solution Approach 1:
The patent introduces DRS (Discovery Reference Signal) as an intermediary element in unlicensed bands, similar to reference signals in licensed bands. The DRS provides a periodic reference signal that enables accurate RSSI measurement and interference estimation, resolving the contradiction by adding a mediating reference signal structure to unlicensed bands without completely changing the measurement methodology
Solution Approach 2:
The patent changes the measurement parameters by introducing DRS-specific measurement configurations including measurement timing, frequency locations, and power levels. This allows the existing RSSI measurement mechanism to work accurately in unlicensed bands by adapting the measurement parameters to match the DRS signal characteristics
2Productivity
If carrier aggregation includes unlicensed bands, then spectral efficiency is improved, but device complexity increases due to multi-band interference measurement requirements
Solution Approach 1:
The patent creates a universal measurement framework that handles both licensed and unlicensed bands through a common RSSI measurement mechanism. The same measurement principles and processing methods are applied across different band types, reducing device complexity by avoiding separate measurement systems for each band type
Solution Approach 2:
The patent segments the measurement configuration into band-specific parameters (such as DRS timing for unlicensed bands, reference signal timing for licensed bands) while maintaining a unified measurement framework. This segmentation allows flexible adaptation to different band characteristics without requiring complete separate measurement systems
3Reliability
If cell selection in carrier aggregation considers unlicensed band interference, then communication reliability is improved, but measurement difficulty increases due to non-periodic signal transmission
Solution Approach 1:
The patent introduces periodic DRS transmission in unlicensed bands, transforming the previously non-periodic signal transmission into a periodic pattern. This periodic action enables reliable interference measurement and cell selection by providing predictable, recurring reference signals that can be consistently measured and evaluated
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
The present invention is designed to improve spectral efficiency in communication using unlicensed carriers. A user terminal for use in a radio communication system to employ LBT (Listen Before Talk) is provided, and this user terminal has a measurement section that makes a measurement for a specific frequency carrier, based on measurement timing configuration information that relates to the specific frequency carrier and that is transmitted from a radio base station, and a transmission section that transmits a measurement result to the radio base station.