Hybrid Beamforming Architecture with Full-Digital Array Segmentation

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Solution Overview

Problem

In hybrid beamformers, the connection of converters and antenna elements affects radio performance, making it challenging to configure circuitry and antenna elements effectively, especially due to varying channel characteristics.

Innovation Solution

A radio communication device with a full-digital array and a hybrid beamformer, where the full-digital array transmits signals subjected to full-digital beamforming, and the hybrid beamformer transmits signals subjected to a combination of digital precoding and analog beamforming, with calibration signals exchanged between the two to optimize configuration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If hybrid beamforming is used with analog variable phase shifters, then circuit complexity is reduced, but radio performance optimization becomes difficult due to fixed connection configurations

Engineering Contradiction:
Improvecircuit complexityVSAvoidconfiguration adaptability
Core Design Contradiction:
Device complexityVSAdaptability or versatility

Solution Approach 1:

The antenna array is segmented into multiple sub-arrays, each with its own analog beamforming network. This allows independent optimization of each sub-array while reducing the overall circuit complexity compared to a fully digital system. The segmentation enables the patent to achieve both lower complexity and better adaptability.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces dynamic switching mechanisms that allow the connection configuration between converters and antenna elements to be changed based on channel conditions. This dynamic reconfiguration capability resolves the contradiction by maintaining simple analog beamforming circuits while enabling adaptive optimization of radio performance through multiple configurable connection patterns.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If full-digital beamforming is used, then beamforming flexibility and interference reduction are improved, but circuit complexity and cost increase significantly

Engineering Contradiction:
Improvebeamforming flexibilityVSAvoidcircuit complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies digital signal processing selectively to specific sub-arrays or specific signal paths rather than all antenna elements. This local application of digital beamforming provides the necessary flexibility and interference reduction in critical areas while avoiding the prohibitive circuit complexity of full-digital beamforming across the entire array.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent merges analog and digital beamforming techniques into a hybrid architecture where analog beamforming handles the majority of signal processing with simple phase shifters, while digital processing is combined selectively for specific functions. This combination achieves good beamforming flexibility without the full circuit complexity of a completely digital system.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If the number of antenna elements is increased for massive-MIMO, then signal transmission speed and quality are improved, but inter-beam interference increases with analog beamforming

Engineering Contradiction:
Improvesignal transmission speedVSAvoidinter-beam interference
Core Design Contradiction:
ProductivityVSObject-generated harmful factors

Solution Approach 1:

The patent introduces digital signal processing as an intermediary layer between the analog beamforming networks and the antenna elements. This digital intermediary can actively manage and reduce inter-beam interference through digital beamforming algorithms while maintaining the benefits of analog beamforming for achieving high signal transmission speeds with large antenna arrays.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent dynamically changes beamforming parameters including phase, amplitude, and connection configurations based on channel conditions and interference levels. By adjusting these parameters, the system can maintain high transmission speeds with massive antenna elements while actively reducing inter-beam interference through adaptive parameter optimization.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3413477B1Radio communication device
Publication Date: 2020.10.21 NTT DOCOMO INC
  • EP3413477B1 patent drawingFigure 1~3
  • EP3413477B1 patent drawingFigure 4
  • EP3413477B1 patent drawingFigure 5

AI summary

A radio communication device includes: a full-digital array that has a first antenna element group including multiple antenna elements and that has no analog variable phase shifter; and a hybrid beamformer that has a second antenna element group including multiple antenna elements and that has an analog variable phase shifter.