CSI-RS Muting for Accurate Channel Estimation

Solution Overview

Problem

In next-generation mobile communication systems, channel quality estimation using CSI-RS is hindered by interference from neighboring cells, leading to inaccurate measurements due to varying transmission cycles of CSI-RS subframes.

Innovation Solution

A base station apparatus allocates CSI-RS and sets muting resources to suppress interference, reporting muting interval information to mobile terminals for accurate channel estimation, ensuring consistent accuracy even with varying subframe transmission cycles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If CSI-RS transmission cycle is varied to support multiple mobile communication systems, then system adaptability is improved, but channel quality estimation accuracy deteriorates due to interference from neighboring cells

Engineering Contradiction:

Improvesystem adaptabilityVSAvoidchannel quality estimation accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The patent divides the CSI-RS transmission into different time slots (subframes) and introduces muting patterns that segment the transmission timeline. By creating specific time intervals where neighboring cells mute their CSI-RS transmission, the patent enables accurate channel quality measurement in the serving cell without interference from neighboring cells, thus resolving the contradiction between system adaptability and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements periodic muting patterns where CSI-RS transmission is alternated with muting intervals. This periodic action creates predictable time windows where interference from neighboring cells is suppressed, allowing mobile terminals to perform accurate channel quality estimation. The periodic muting pattern enables the system to maintain adaptability across multiple communication systems while ensuring measurement accuracy during designated time slots.

Inventive Principle:

Principle #19Periodic action

2Measurement precision

If muting is applied to suppress interference from neighboring cells, then channel quality estimation accuracy is improved, but data transmission throughput deteriorates

Engineering Contradiction:

Improvechannel quality estimation accuracyVSAvoiddata transmission throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The patent applies muting selectively only in specific time slots and frequency resources where interference from neighboring cells affects channel quality measurement. Rather than continuously muting CSI-RS transmission, the patent localizes muting to specific intervals (e.g., every 10th subframe) and only in resources occupied by neighboring cells' CSI-RS. This localized approach suppresses interference during measurement periods while maintaining normal data transmission throughput during other time slots.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements periodic muting patterns where CSI-RS transmission is alternated with muting intervals. This periodic action creates predictable time windows where interference from neighboring cells is suppressed, allowing mobile terminals to perform accurate channel quality estimation. The periodic muting pattern enables the system to maintain adaptability across multiple communication systems while ensuring measurement accuracy during designated time slots.

Inventive Principle:

Principle #19Periodic action

3Device complexity

If CSI-RS transmission resources are allocated continuously, then system simplicity is maintained, but interference from neighboring cells increases measurement error

Engineering Contradiction:

Improvesystem simplicityVSAvoidchannel quality estimation accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent divides the CSI-RS transmission into different time slots (subframes) and introduces muting patterns that segment the transmission timeline. By creating specific time intervals where neighboring cells mute their CSI-RS transmission, the patent enables accurate channel quality measurement in the serving cell without interference from neighboring cells, thus resolving the contradiction between system adaptability and measurement precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements a feedback mechanism where the base station transmits muting pattern information to mobile terminals, and the terminals use this feedback to accurately identify when muting occurs and adjust their measurement timing accordingly. This feedback mechanism ensures that mobile terminals can accurately measure channel quality during muting intervals without interference, while the base station maintains control over the muting pattern configuration.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2627020B1Base station device, mobile terminal device, and communication control method

Publication Date: 2020.07.15 NTT DOCOMO INC

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Figure 3A~3F

AI summary

The present invention provides a base station apparatus, a mobile terminal apparatus and a communication control method which can improve the accuracy of channel quality estimation. A communication control method includes the steps of: allocating a CSI-RS (Channel State Information-Reference Signal), which is a reference signal for downlink channel estimation, in resources for the CSI-RS that are defined for CSI-RS transmission; setting muting resources in the resources for the CSI-RS; and reporting parameters to specify the CSI-RS, including at least a transmitting subframe cycle, a subframe offset and transmission power, to a mobile terminal apparatus.