Uplink MIMO Precoding Using Complex Hadamard Matrices

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Solution Overview

Problem

Current 5G NR technology is limited by wideband precoding and table-based codebooks that do not match non-uniform linear antenna architectures, leading to inefficient power usage and reduced spatial resolution in uplink MIMO transmissions.

Innovation Solution

Implementing a full-rank complex Hadamard matrix (CHM) for precoding uplink signals, allowing for higher spatial resolution and adaptable precoding matrices that balance power across transmit antenna elements, supporting both uniform and non-uniform linear arrays.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of information

If a table-based codebook with limited table size is used to control signaling overhead, then signaling overhead is reduced, but spatial resolution is compromised

Engineering Contradiction:

Improvespatial resolutionVSAvoidcodebook table size

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The patent changes the fundamental parameter of codebook representation from discrete table-based indices to continuous complex Hadamard matrix constructions. This allows the precoding matrix to be fully specified by a small number of parameters (phase shifts and scaling factors) rather than requiring large lookup tables, thereby achieving high spatial resolution without increasing signaling overhead.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent replaces the mechanical table-lookup system with a mathematical construction system based on complex Hadamard matrices. Instead of selecting from pre-defined tables, the precoding matrix is constructed on-the-fly using deterministic mathematical formulas, eliminating the need for large codebook tables while maintaining or improving spatial resolution.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If wideband precoding is used in current NR uplink MIMO, then implementation is simplified, but spatial resolution and adaptability are limited

Engineering Contradiction:

Improvespatial resolutionVSAvoidprecoding implementation complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces dynamic precoding capabilities where the precoding matrix can be adapted to specific frequency resources and spatial conditions. The complex Hadamard matrix construction allows for flexible adjustment of phase and amplitude parameters based on channel conditions, enabling both wideband and subband precoding modes without significantly increasing implementation complexity.

Inventive Principle:

Principle #15Dynamics

3Reliability

If current codebook design is used for non-ULA antenna architecture, then compatibility with existing systems is maintained, but precoding performance deteriorates

Engineering Contradiction:

Improveprecoding performanceVSAvoidantenna architecture adaptability

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent creates a universal precoding framework based on complex Hadamard matrices that can accommodate various antenna architectures including ULA, non-ULA, uniform rectangular arrays, and non-uniform rectangular arrays. The mathematical construction is architecture-agnostic, allowing the same precoding mechanism to work across different physical antenna configurations without requiring architecture-specific codebooks.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12476680B2High spatial resolution MIMO precoding for uplink communication

Publication Date: 2025.11.18 MEDIATEK SINGAPORE PTE LTD

AI summary

A user equipment (UE) with N transmit (Tx) antenna elements in a wireless network receives precoding information from a base station. The UE constructs a full-rank complex Hadamard matrix (CHM) of order N using the precoding information. The UE then precodes uplink signal using a precoding matrix composed of one or more columns of the full-rank CHM, and transmits the precoded uplink signal to the base station.