Hybrid Beamforming Wireless Backhaul Interference Control

Solution Overview

Problem

In 5G mobile communication systems using millimeter wave band, wireless backhaul between macro-cell and small-cell base stations causes interference with terminals due to high transmission power and beamforming, leading to reduced frequency capacity and service stability.

Innovation Solution

A method that generates and uses reception status and interference information to optimize beamforming signals, minimizing interference by selecting appropriate beamforming signals for wireless backhaul connections between macro-cell and small-cell base stations, even when sharing the same frequency/time resources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If beamforming-based wireless backhaul is used between macro-cell BS and small-cell BS, then frequency capacity is improved by allowing same frequency/time resources to be shared, but interference with terminals increases due to high transmission power and sidelobes

Engineering Contradiction:

Improvefrequency capacityVSAvoidinterference with terminal

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating between main lobe and sidelobe regions in the beamforming signal. The macro-cell BS transmits backhaul signals with high gain in the main lobe direction toward the small-cell BS, while specifically suppressing sidelobe gains in directions where terminals are located. This allows frequency reuse with terminals while minimizing interference through directional signal characterization.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent implements feedback mechanisms where the small-cell BS measures interference levels caused by the macro-cell backhaul signals and reports this information to the macro-cell BS. Based on this feedback, the macro-cell BS adjusts its beamforming weights and sidelobe suppression strategies to optimize the trade-off between backhaul performance and terminal interference protection.

Inventive Principle:

Principle #23Feedback

2Reliability

If high transmission power is used for macro-cell BS backhaul signals, then backhaul link reliability is improved, but interference with terminals increases

Engineering Contradiction:

Improvebackhaul link reliabilityVSAvoidinterference with terminal

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by differentiating between main lobe and sidelobe regions in the beamforming signal. The macro-cell BS transmits backhaul signals with high gain in the main lobe direction toward the small-cell BS, while specifically suppressing sidelobe gains in directions where terminals are located. This allows frequency reuse with terminals while minimizing interference through directional signal characterization.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes the beamforming parameter space by introducing sidelobe suppression constraints in addition to main lobe beamforming. The macro-cell BS optimizes multiple parameters including beam direction, gain, and sidelobe level to achieve reliable backhaul communication while controlling interference. This involves adjusting beamforming weights to maintain high signal quality for the backhaul link while limiting interference in terminal directions.

Inventive Principle:

Principle #35Parameter changes

3Device complexity

If hybrid beamforming structure is used, then system complexity is reduced compared to fully digital beamforming, but sidelobe interference control becomes more challenging

Engineering Contradiction:

Improvesystem complexityVSAvoidsidelobe interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent applies segmentation by dividing the beamforming function into two separate stages: analog beamforming for coarse directional control and digital beamforming for fine-grained sidelobe suppression. The analog beamformer creates initial directional beams, while the digital beamformer optimizes weights to suppress sidelobes. This segmentation allows hybrid beamforming to achieve better interference control than pure analog systems while maintaining lower complexity than fully digital systems.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the beamforming parameter space by introducing sidelobe suppression constraints in addition to main lobe beamforming. The macro-cell BS optimizes multiple parameters including beam direction, gain, and sidelobe level to achieve reliable backhaul communication while controlling interference. This involves adjusting beamforming weights to maintain high signal quality for the backhaul link while limiting interference in terminal directions.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentEP3324669B1Wireless communication method using hybrid beamforming, and apparatus therefor

Publication Date: 2025.03.19 SK TELECOM CO LTD

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AI summary

The present invention relates to a wireless communication technology, and more specifically, to a method and an apparatus for connecting a wireless backhaul by generating reception status information, and interference information or location information, on the basis of a beamforming signal at the time of configuration of a wireless backhaul between base stations through beamforming.