Beamforming Codebooks Using Approximate Channel Decomposition

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Solution Overview

Problem

Existing 5G wireless communication systems face challenges in achieving optimal performance across a wide range of spatial correlations due to the limitations of standard codebooks designed for regular antenna arrays, which fail to accommodate irregular antenna configurations.

Innovation Solution

The development of beamforming techniques using approximate channel decomposition, specifically through non-constant modulus (NCM) codebooks based on constant modulus (CM) codebooks and NCM component matrices, allowing for flexible trade-offs between system performance and signaling overhead.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If standard codebooks designed for regular antenna arrays are used, then system performance is optimized for uniform linear arrays, but performance degrades under irregular antenna configurations and diverse spatial correlations

Engineering Contradiction:

Improveadaptability to diverse antenna configurationsVSAvoidsystem performance under irregular arrays

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent transforms the fixed-parameter codebook design into a flexible framework by introducing variable parameters including NCM/CM mode selection, rank adaptation, and codebook type selection. The system can dynamically adjust between constant modulus and non-constant modulus codebooks based on channel conditions and antenna configurations, enabling optimal performance across diverse spatial correlations and irregular array deployments

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The codebook design achieves universality by creating a single framework that serves multiple antenna configurations (ULA, irregular arrays, cylindrical arrays) and multiple spatial correlation scenarios. The NCM codebook with approximate decomposition can function as both constant modulus and non-constant modulus codebook depending on the deployment scenario, eliminating the need for separate codebook designs for different array types

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Reliability

If non-constant modulus codebooks are used to improve performance under diverse spatial correlations, then system performance increases, but feedback overhead increases

Engineering Contradiction:

Improvesystem performance under diverse spatial correlationsVSAvoidfeedback overhead

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The system implements dynamic codebook operation by allowing the wireless device to select between NCM and CM modes based on current channel conditions and spatial correlation characteristics. This dynamic switching capability enables the system to use NCM codebooks when performance benefits outweigh feedback overhead, and switch to CM codebooks when overhead concerns dominate, optimizing the trade-off in real-time

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The approximate decomposition method provides a partial solution by decomposing the NCM codebook into CM component and NCM component matrices. This partial decomposition reduces the feedback overhead compared to full NCM codebook representation while maintaining most of the performance benefits, striking a practical balance between accuracy and overhead

Inventive Principle:

Principle #16Partial or excessive action

3Device complexity

If constant modulus codebooks are used, then implementation is simpler and more compatible with existing systems, but performance is limited under irregular antenna configurations

Engineering Contradiction:

Improvecodebook implementation complexityVSAvoidperformance under irregular antenna configurations

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The NCM codebook is segmented into two distinct components: a CM component matrix that provides structural framework and compatibility, and an NCM component matrix that provides performance enhancement. This segmentation allows the system to leverage the simplicity of CM codebooks while incorporating the performance benefits of NCM codebooks, reducing overall implementation complexity compared to pure NCM approaches

Inventive Principle:

Principle #1Segmentation

Data Source

PatentUS12476679B2Beamforming technique using approximate channel decomposition

Publication Date: 2025.11.18 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method, system and apparatus for beamforming techniques that use approximate channel decomposition are disclosed. According to one aspect, a wireless device is provided. The wireless device includes processing circuitry configured to use a non-constant modulus, NCM, precoder of a NCM codebook to transmit on a physical channel where the NCM codebook is based at least in part on a constant modulus, CM, codebook and a plurality of NCM component matrices, and where the plurality of NCM component matrices are based at least in part on a NCM component matrix mathematical expression, and where an approximate decomposition element-wise product of a CM component matrix mathematical expression and the NCM component matrix mathematical expression corresponds to a channel decomposition matrix.