Hybrid FD-MIMO Beamforming Combining Codebook and Reciprocity

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Solution Overview

Problem

Current codebook-based transmission modes in wireless communications do not fully utilize elevation beamforming, leading to sub-optimal performance in Full Dimension Multiple Input Multiple Output (FD-MIMO) due to the lack of vertical beamforming information.

Innovation Solution

Combining codebook-based and reciprocity-based one direction grid of beams (1D GoB) beamforming to enable both horizontal and vertical beamforming, allowing the base station to estimate the best vertical beam and combine it with user equipment (UE) reported Precoder Matrix Indicators (PMI) for horizontal beamforming, creating a 2D beamformer for downlink transmissions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If codebook-based transmission modes are used with PMI for horizontal beamforming, then horizontal beamforming is achieved, but elevation beamforming is not fully utilized leading to sub-optimal FD-MIMO performance

Engineering Contradiction:

Improvebeamforming capabilityVSAvoidFD-MIMO performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent extends the traditional 1D horizontal beamforming codebook to 2D by incorporating elevation dimension. The codebook is restructured to include both azimuth and elevation beamforming vectors, transforming the beamforming capability from single-dimensional to two-dimensional to fully utilize FD-MIMO potential

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent combines horizontal beamforming (from PMI) and vertical beamforming (from 1D GoB) into a unified 2D beamformer. The codebook merges both horizontal and vertical codebook indices to create a composite beamforming structure that simultaneously performs both dimensions

Inventive Principle:

Principle #5Merging (Combining)

2Ease of operation

If traditional codebook-based beamforming is used, then implementation is straightforward, but both horizontal and vertical beamforming cannot be performed simultaneously

Engineering Contradiction:

Improvebeamforming implementationVSAvoid2D beamforming capability

Core Design Contradiction:

Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent segments the 2D beamforming problem into two independent 1D problems: horizontal beamforming handled by PMI and vertical beamforming handled by 1D GoB. This segmentation allows each dimension to be processed separately using established methods while achieving comprehensive 2D coverage

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent creates a universal codebook structure that can handle both horizontal and vertical beamforming through a single unified interface. The codebook design allows it to serve multiple functions: horizontal beamforming, vertical beamforming, and their combination, making it adaptable to different transmission scenarios

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS11509366B2Hybrid FD-MIMO: combining codebook-based and reciprocity-based beamforming

Publication Date: 2022.11.22 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A method, system and apparatus for realizing FD_MIMO in codebook-based transmissions. The method, system and apparatus include the combing of one or more horizontal codebooks and one or more vertical codebooks. A 2D beamformer for downlink transmissions is generated based on the combination of the one or more horizontal codebooks and one or more vertical codebooks.