UE Channel Quality Reporting With Multiple CSI-IM Configurations
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Solution Overview
Problem
In LTE systems, user equipment (UE) measurements of channel quality indicators (CQI) are often inaccurate due to interference, leading to overestimation or underestimation, which affects reception performance.
Innovation Solution
The implementation of a channel quality reporting method that configures and uses multiple interference measurement configurations (CSI-IMs) for different transmission points, allowing the UE to transmit CQIs measured using these configurations, and the base station to select the appropriate CQI for scheduling based on interference removal support information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the UE measures CQI without considering interference removal function, then the measurement process is simple, but the CQI accuracy deteriorates due to overestimation or underestimation
Solution Approach 1:
The interference measurement is segmented into multiple CSI-IM resources, each configured to measure interference from specific transmission points. The UE measures CQI separately for each CSI-IM resource, allowing accurate representation of interference from different sources without complicating the overall measurement process
Solution Approach 2:
The system changes the interference measurement parameters by configuring multiple CSI-IM resources with different interference hypotheses (with or without interference removal). This allows the UE to report accurate CQI values that reflect actual interference conditions while maintaining measurement simplicity through standardized procedures
2Measurement precision
If multiple CSI-IM configurations are used to measure interference from different transmission points, then the CQI accuracy improves, but the device complexity increases
Solution Approach 1:
Multiple CSI-IM resources are configured with universal measurement procedures that can handle different interference scenarios. Each CSI-IM resource serves multiple purposes: measuring interference from specific TPs, supporting both interference removal and non-interference removal cases, and enabling accurate CQI reporting without requiring separate measurement mechanisms for each scenario
Solution Approach 2:
The base station performs preliminary configuration of multiple CSI-IM resources with specific interference hypotheses before UE measurement. This pre-configuration eliminates the need for complex real-time decision-making by the UE and simplifies the measurement process while maintaining high CQI accuracy through pre-planned interference measurement strategies
3Ease of operation
If the UE reports CQI without accounting for interference scenarios, then the reporting process is simple, but the reception performance deteriorates
Solution Approach 1:
The UE provides feedback by reporting CQI values measured from different CSI-IM resources, each representing different interference scenarios. This feedback mechanism enables the base station to select appropriate transmission strategies based on actual interference conditions, improving reception performance while keeping the reporting process simple through standardized CQI feedback procedures
Data Source
AI summary
One embodiment of the present specification provides a method by which a user equipment (UE) reports channel quality. According to the method, the UE can receive a channel state information-interference measurement (CSI-IM) configuration of first and second transmission points (TPs). Here, the CSI-IM configuration includes at least three configurations for the CSI-IM, and the at least three configurations for CSI-IM can include a first CSI-IM configuration for measuring interference to the first TP caused by the second TP, a second CSI-IM configuration for measuring interference to the second TP caused by the first TP, and a third CSI-IM configuration for measuring interference from other interference sources. Therefore, according to the channel quality reporting method, the UE can feed a channel quality indicator (CQI) measured using the first CSI-IM configuration and a CQI measured using the third CSI-IM configuration back to the first TP.