Zero-Power CSI-RS for Interference Measurement in CoMP Systems
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Solution Overview
Problem
In LTE-A systems, accurately measuring channel state information (CSI) for coordinated multiple-point (CoMP) transmission/reception is challenging due to the low density of CSI-RSs, which affects interference measurement between cells, limiting the ability of user terminals to feed back optimal channel quality information for multiple transmission points.
Innovation Solution
The introduction of zero-power CSI-RSs for interference measurement, strategically positioned to avoid overlapping with data channels, allows for increased accuracy and efficiency in interference measurement, enabling user terminals to feed back optimal CSI by distinguishing between desired and interference signals based on resource allocation patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If non-zero power CSI-RS resources are introduced for interference measurement, then the number of resources for interference measurement increases, but the processing load and complexity of distinguishing desired and interference signals increases
Solution Approach 1:
The patent extracts the interference measurement function from the data transmission resources by introducing dedicated zero-power CSI-RS resources. These specialized resources are specifically designed for interference measurement, allowing the UE to measure interference without processing desired signal components, thereby reducing processing load while increasing the number of available measurement resources.
Solution Approach 2:
Zero-power CSI-RS resources act as an intermediary mechanism between channel estimation and interference measurement. By using these dedicated resources, the system enables accurate interference measurement without requiring the UE to separate desired and interference signals from data channels, thus reducing complexity while providing more measurement opportunities.
2Measurement precision
If zero power CSI-RS resources are introduced for interference measurement, then interference measurement accuracy improves, but the system complexity and configuration overhead increases
Solution Approach 1:
The patent segments the CSI-RS resources into different types: non-zero power CSI-RS for channel estimation and zero-power CSI-RS for interference measurement. This segmentation allows each resource type to be optimized for its specific purpose, improving measurement accuracy while managing complexity through standardized configuration procedures.
Solution Approach 2:
The patent changes the power parameter of CSI-RS resources to zero for interference measurement purposes. By setting transmission power to zero on these dedicated resources, the system eliminates desired signal components, allowing pure interference measurement. The configuration overhead is managed through RRC signaling that defines these specialized resource patterns.
3Adaptability or versatility
If multiple CSI-RS configurations are used for CoMP operation, then the ability to support multiple transmission points improves, but the RRC configuration complexity and feedback overhead increases
Solution Approach 1:
The patent creates a universal framework where zero-power CSI-RS resources can be configured for multiple transmission points using the same measurement mechanism. The UE measures interference from all non-serving transmission points on these dedicated resources, providing universal interference measurement capability across multiple CoMP transmission points without requiring separate measurement procedures for each point.
Data Source
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AI summary
The present invention is designed to provide a wireless communication system, a base station apparatus, a user terminal, and a channel state information measurement method that can allow a user terminal to feed back channel quality information that is optimal for a transmission mode from a plurality of transmission points. A wireless communication system according to the present invention provides a base station apparatus having a determining section that determines resource information about resources to allocate the reference signal for measuring desired signals to, and resource for measuring interference signals, and a reporting section that reports the resource information to the user terminal, and the user terminal having a receiving section that receives the reported resource information, a measurement section that measures desired signals and interference signals based on the resource information, and a measurement section that measures the channel state using the measurement results of the measurement section.