Correction Matrix for Implicit Beamforming in MIMO Systems

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Solution Overview

Problem

Implicit beamforming in wireless communication systems is impaired by RF chain impairments such as gain/phase imbalances and coupling losses, which disrupt the ideal reciprocity between forward and reverse channels, necessitating additional calibration exchanges.

Innovation Solution

A method and system that use a correction matrix to account for these impairments by estimating the forward channel based on partial dimensional descriptions of both the forward and reverse channels, allowing for beamforming without the need for explicit calibration signals.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If implicit beamforming is used to reduce calibration exchanges, then productivity is improved, but reliability deteriorates due to RF chain impairments

Engineering Contradiction:

Improvebeamforming setup efficiencyVSAvoidbeamforming performance

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

A correction matrix is introduced as an intermediary component that mediates between the implicit beamforming approach and RF chain impairments. The correction matrix captures calibration information and compensates for gain/phase imbalances and coupling losses, allowing the system to maintain reliability while using implicit beamforming for efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The system performs preliminary calibration exchanges to obtain correction matrices before actual beamforming operations. These pre-computed correction matrices are stored and applied during subsequent communications, eliminating the need for repeated calibration while maintaining accurate compensation for RF chain impairments.

Inventive Principle:

Principle #10Preliminary action

2Reliability

If explicit calibration signals are used to compensate for RF chain impairments, then reliability is improved, but device complexity increases

Engineering Contradiction:

Improvebeamforming performanceVSAvoidcalibration exchange overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Instead of performing full explicit calibration for every beamforming operation, the system uses partial calibration through correction matrices obtained during initial setup or periodic updates. This partial action approach maintains sufficient reliability while significantly reducing the complexity of repeated calibration exchanges.

Inventive Principle:

Principle #16Partial or excessive action

3Reliability

If correction matrix is applied to compensate for RF chain impairments, then reliability is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improvebeamforming performanceVSAvoidRF chain calibration accuracy

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The correction matrix is derived from actual measured channel characteristics during calibration exchanges, allowing the system to self-characterize and self-correct RF chain impairments. This self-service approach adapts to actual hardware variations without requiring extremely tight manufacturing tolerances, as the correction is computed based on real-world performance data.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS8971178B1Calibration correction for implicit beamformer using an explicit beamforming technique in a wireless MIMO communication system

Publication Date: 2015.03.03 VELOCITY COMMUNICATION TECHNOLOGIES LLC

AI summary

A transmitter beamforming technique for use in a MIMO wireless communication system determines (i) a partial description of a reverse channel without determining a full dimensional description of the reverse channel and (ii) a partial description of a forward channel without determining a full dimensional description of the forward channel. A correction matrix is developed from the partial description of the reverse channel and a partial description of the forward channel. The correction matrix is used to process signals to be transmitted via the forward channel, and a steering matrix is used to perform beamforming in the forward channel.