Hybrid Precoding for MU-MIMO Channel Estimation

Solution Overview

Problem

As wireless communication standards evolve, particularly with the expected support for high-order multi-user multiple-input multiple-output (MU-MIMO) in 5G-advanced or 6G base stations, the computational complexity increases significantly, necessitating efficient methods for channel estimation, hybrid precoding, and scheduling to maintain spectral efficiency and power efficiency.

Innovation Solution

The method involves selecting a set of orthogonal beams for SRS full-channel reconstruction and generating an analog precoding matrix for hybrid analog-digital precoding in MU-MIMO systems, which includes using techniques like normal DFT, rotated DFT, eigenvalue decomposition, and AI/ML to determine the analog beamformer, and iteratively optimizing analog beamforming for scheduled users to reduce complexity and improve performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high order MU-MIMO (16-layer or 32-layer) is implemented to provide higher spectral efficiency and beamforming gain, then spectral efficiency and power efficiency are improved, but computational complexity increases significantly

Engineering Contradiction:

Improvespectral efficiencyVSAvoidcomputational complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent segments the precoding operation into two independent parts: analog precoding matrix (W RF) and digital precoding matrix (W BB). The analog precoder handles the majority of the beamforming gain with lower computational complexity, while the digital precoder handles user-specific signal processing. This segmentation allows high-order MU-MIMO to achieve high spectral efficiency without proportionally increasing overall computational complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies partial digital processing (only at the baseband level for user-specific signal processing) rather than full digital processing throughout the entire signal chain. By using analog beamforming for the bulk of the signal processing and reserving digital processing only for essential user-specific operations, the system achieves high efficiency with reduced computational complexity.

Inventive Principle:

Principle #16Partial or excessive action

2Use of energy by stationary object

If the number of MU-MIMO layers is increased to achieve higher beamforming gain, then power efficiency is improved, but the complexity of channel estimation and precoding increases

Engineering Contradiction:

Improvepower efficiencyVSAvoidcomplexity of channel estimation and precoding

Core Design Contradiction:

Use of energy by stationary objectVSDevice complexity

Solution Approach 1:

The patent segments the precoding operation into two independent parts: analog precoding matrix (W RF) and digital precoding matrix (W BB). The analog precoder handles the majority of the beamforming gain with lower computational complexity, while the digital precoder handles user-specific signal processing. This segmentation allows high-order MU-MIMO to achieve high spectral efficiency without proportionally increasing overall computational complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs channel estimation using a reduced set of beams (e.g., 8 beams) as a preliminary step before actual data transmission. This preliminary channel estimation enables the system to configure the analog precoder in advance, reducing the computational burden during actual communication and enabling higher order MU-MIMO operations.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If full digital precoding is used to handle multiple users, then signal processing flexibility is improved, but power consumption and computational complexity increase

Engineering Contradiction:

Improvesignal processing flexibilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent segments the precoding operation into two independent parts: analog precoding matrix (W RF) and digital precoding matrix (W BB). The analog precoder handles the majority of the beamforming gain with lower computational complexity, while the digital precoder handles user-specific signal processing. This segmentation allows high-order MU-MIMO to achieve high spectral efficiency without proportionally increasing overall computational complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces extensive digital signal processing operations with analog beamforming operations. By using analog phase shifters and amplifiers to perform beamforming, the system reduces the computational burden on digital processors, thereby lowering power consumption while maintaining signal processing flexibility for multiple users.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20240333367A1Channel estimation, hybrid precoding, and scheduling of multi-user MIMO

Publication Date: 2024.10.03 SAMSUNG ELECTRONICS CO LTD

AI summary

A method includes selecting a set of orthogonal beams to be used for SRS full-channel reconstruction in a multi-user multiple-input multiple-output (MU-MIMO) system. The method also includes generating an analog precoding matrix for hybrid analog-digital precoding in the MU-MIMO system. The method further includes communicating with multiple users using the MU-MIMO system and the analog precoding matrix.