Restricted Frequency-Domain Beamforming for Lower-Complexity CSI Reporting

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Solution Overview

Problem

Existing CSI reporting mechanisms in wireless communication systems, particularly in 5G NR, face challenges in efficiently reducing complexity and overhead while maintaining accuracy, especially in scenarios where DL-UL reciprocity is partial.

Innovation Solution

Implementing a restricted set of frequency domain beamforming components and spatial-frequency beamforming groups for CSI-RS ports, allowing UEs to provide precise CSI feedback with reduced complexity and power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a full set of frequency domain beamforming components is used for CSI reporting, then CSI reporting accuracy is improved, but computational complexity and overhead at UEs increase

Engineering Contradiction:

ImproveCSI reporting accuracyVSAvoidcomputational complexity at UEs

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent extracts and reports only the most significant beamforming components (e.g., dominant eigenvectors or components with highest channel gain) rather than the full set of components. This selective extraction reduces the number of parameters to be reported and processed, thereby reducing computational complexity and overhead while preserving the most important channel state information for accurate precoding

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent changes the parameter representation by transforming the complete channel state information into a reduced set of parameters that capture the essential beamforming characteristics. This includes reporting only a subset of beamforming component indices, amplitudes, and phases, which reduces the dimensionality of the feedback while maintaining sufficient accuracy for effective precoding

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If a restricted set of frequency domain beamforming components is used for CSI reporting, then computational burden at UEs is reduced, but CSI reporting accuracy may deteriorate

Engineering Contradiction:

Improvecomputational burden at UEsVSAvoidCSI reporting accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent applies partial action by reporting a sufficient subset of beamforming components that captures the dominant channel characteristics without reporting all components. The restricted set is carefully selected to include the most significant components (e.g., top K eigenvectors or components with highest power), providing 'enough' information for accurate precoding while avoiding the excessive burden of processing and reporting the complete set

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent segments the frequency domain beamforming components into multiple groups or layers, where the most significant components are reported with higher precision or priority. This segmentation allows the system to focus computational resources on the most important channel dimensions while using coarser or no reporting for less significant components, thereby reducing overall complexity while maintaining accuracy for the dominant signal paths

Inventive Principle:

Principle #1Segmentation

3Productivity

If spatial-frequency beamforming groups are implemented for CSI-RS ports, then resource utilization is optimized, but system complexity increases

Engineering Contradiction:

Improveresource utilizationVSAvoidsystem complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent merges spatial and frequency domain beamforming operations into unified groups of CSI-RS ports. By combining spatial layers and frequency subbands into structured groups, the system can perform joint beamforming optimization across both domains, improving resource utilization through more efficient spatial-frequency resource allocation while managing complexity through standardized grouping patterns

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The patent implements dynamic spatial-frequency beamforming groups that can be adaptively configured based on channel conditions, traffic requirements, and UE capabilities. The grouping structure allows flexible adjustment of the number and composition of groups, enabling the system to optimize resource utilization dynamically while managing complexity through configurable parameters rather than fixed rigid structures

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS12431953B2Indication of information in channel state information (CSI) reporting

Publication Date: 2025.09.30 QUALCOMM INC

AI summary

Wireless communications systems and methods related to CSI feedback are provided. A user equipment (UE) receives an indication of a restricted set of frequency domain (FD) beamforming components and one or more channel state information reference signals (CSI-RSs). The UE may transmit channel state information (CSI) report indicating a plurality of precoding coefficients based on the received one or more CSI-RSs and the restricted set of FD beamforming components.