Dynamic Subcarrier Spacing for Beamforming Feedback in Massive MIMO

Solution Overview

Problem

Massive multiple-input multiple-output (mMIMO) wireless networks face challenges in providing high-quality service due to varying signal conditions and inefficient beamforming, particularly for mobile devices that experience feedback degradation, leading to poor beam alignment and quality of service issues.

Innovation Solution

The method involves monitoring beamforming feedback from wireless devices and adjusting the subcarrier spacing of access nodes, increasing it when feedback degrades and reducing it when feedback improves, to enhance feedback processing speed and accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the access node uses standard subcarrier spacing for beamforming feedback, then the feedback processing is slower, but the system complexity remains manageable; however, for high mobility devices, the feedback becomes outdated before processing completes

Engineering Contradiction:

Improvefeedback processing speedVSAvoidsystem complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent implements dynamic subcarrier spacing adjustment where the access node monitors feedback quality indicators (such as beamforming feedback accuracy or device mobility metrics) and adaptively changes the subcarrier spacing based on current channel conditions. When feedback degradation is detected, the system increases subcarrier spacing to accelerate feedback processing speed, and reduces it when conditions improve, thereby optimizing performance without permanently increasing system complexity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention changes the subcarrier spacing parameter dynamically based on feedback quality. By adjusting this physical layer parameter, the system can control the timing of feedback transmissions - larger subcarrier spacing reduces feedback duration and processing time, directly addressing the speed requirement while maintaining manageable complexity through parameter optimization rather than architectural changes

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If the access node increases subcarrier spacing to speed up feedback processing, then mobile device feedback accuracy improves, but the overall system throughput may be reduced

Engineering Contradiction:

Improvefeedback accuracyVSAvoidsystem throughput

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The system dynamically adjusts subcarrier spacing based on real-time feedback quality monitoring. When feedback accuracy degrades (indicating the need for larger spacing), the system increases subcarrier spacing temporarily. When feedback quality improves, it reduces spacing back to normal levels. This dynamic adaptation ensures that the throughput penalty is paid only when necessary for feedback accuracy, minimizing the overall impact on system productivity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The access node periodically monitors feedback quality metrics and adjusts subcarrier spacing in response to detected degradation. This periodic monitoring and adjustment mechanism allows the system to maintain high feedback accuracy during periods of degradation while preserving normal throughput during periods of good feedback quality, effectively managing the trade-off between precision and productivity

Inventive Principle:

Principle #19Periodic action

3Adaptability or versatility

If the access node uses fixed beamforming configuration, then the system is simpler to manage, but it cannot adequately serve devices with varying signal conditions and mobility patterns

Engineering Contradiction:

Improvebeamforming adaptabilityVSAvoidbeamforming management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent implements dynamic subcarrier spacing adjustment where the access node monitors feedback quality indicators (such as beamforming feedback accuracy or device mobility metrics) and adaptively changes the subcarrier spacing based on current channel conditions. When feedback degradation is detected, the system increases subcarrier spacing to accelerate feedback processing speed, and reduces it when conditions improve, thereby optimizing performance without permanently increasing system complexity

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The invention utilizes beamforming feedback from wireless devices to monitor feedback quality and trigger subcarrier spacing adjustments. This feedback mechanism enables the system to automatically adapt to varying signal conditions and mobility patterns, improving beamforming adaptability while keeping management complexity manageable through automated closed-loop control rather than manual configuration

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11234245B1Beamforming in massive MIMO networks

Publication Date: 2022.01.25 SPRINT SPECTRUM LP

AI summary

Beamforming in massive MIMO networks includes monitoring beamforming feedback from one or more wireless devices attached to an access node, when the beamforming feedback degrades, increasing a subcarrier spacing of the access node, and when the beamforming feedback stops degrading, maintaining or reducing the subcarrier spacing of the access node.