Hybrid Beamforming Feedback Using Gain Difference

Solution Overview

Problem

In wireless communication systems, existing methods for beamforming in MIMO environments face inefficiencies in feedback information transmission and processing, particularly in hybrid beamforming schemes, which require both digital and analog beamforming directions to be determined accurately and efficiently.

Innovation Solution

A method is introduced where channel state information (CSI) is measured and transmitted by user equipment, including gain differences between directional and omni-directional beams, allowing the base station to determine digital and analog beamforming directions in hybrid beamforming, thereby reducing feedback size and enhancing beamforming efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If traditional feedback methods are used for beamforming in MIMO environments, then beamforming can be performed, but the feedback information size becomes large and processing efficiency decreases

Engineering Contradiction:

Improvebeamforming efficiencyVSAvoidfeedback information size

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The patent extracts only the essential feedback information (gain difference between directional and omni-directional beams) from the complete channel state information, eliminating redundant data. This selective extraction reduces feedback overhead while preserving the critical information needed for hybrid beamforming direction determination.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent transforms the feedback approach by changing from reporting absolute channel state parameters to reporting a derived parameter (gain difference). This parameter transformation compresses the information representation while maintaining the ability to determine both digital and analog beamforming directions accurately.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If detailed channel state information is transmitted for accurate beamforming, then beamforming accuracy is improved, but feedback transmission time and processing complexity increase

Engineering Contradiction:

Improvebeamforming accuracyVSAvoidfeedback transmission time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent extracts only the essential feedback information (gain difference between directional and omni-directional beams) from the complete channel state information, eliminating redundant data. This selective extraction reduces feedback overhead while preserving the critical information needed for hybrid beamforming direction determination.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The base station performs preliminary action by transmitting both directional and omni-directional reference signals before the UE measurement. This allows the UE to efficiently measure and calculate the gain difference without needing to process complete channel matrices, reducing feedback preparation time while maintaining accuracy.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If complete channel state information is fed back for hybrid beamforming, then both digital and analog beamforming directions can be determined, but the feedback overhead increases significantly

Engineering Contradiction:

Improvebeamforming direction determination capabilityVSAvoidfeedback information size

Core Design Contradiction:

Adaptability or versatilityVSQuantity of substance

Solution Approach 1:

The patent transforms the feedback approach by changing from reporting absolute channel state parameters to reporting a derived parameter (gain difference). This parameter transformation compresses the information representation while maintaining the ability to determine both digital and analog beamforming directions accurately.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The gain difference parameter serves multiple functions simultaneously: it indicates the optimal digital beamforming direction, provides information for analog beamforming direction determination, and enables hybrid beamforming optimization. This multi-functionality reduces feedback overhead while maintaining comprehensive beamforming capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentEP3117533B1Method of feedback for beamforming in a wireless communication system and apparatus therefor

Publication Date: 2019.09.18 LG ELECTRONICS INC

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AI summary

A method of transmitting channel state information (CSI) for a hybrid beamforming from a user equipment in a wireless communication system according to one embodiment of the present invention may include measuring a gain of a directional beam formed with reference to a first direction and a gain of an omni-directional beam formed equivalently in all directions respectively and transmitting the CSI including a gain difference between the directional beam and the omni-directional beam to a base station, wherein a direction of a digital beamforming in the hybrid beamforming is determined in accordance with the gain difference between the directional beam and the omni-directional beam and wherein a direction of an analog beamforming in the hybrid beamforming is determined in accordance with the first direction.