MIMO Transmitter Impairment Compensation via EVM Feedback

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Solution Overview

Problem

MIMO beamforming communication systems face performance losses due to transmitter-induced noise, which conventional methods struggle to compensate for effectively, leading to errors in decoding and stringent requirements for expensive circuitry to maintain acceptable bit error and packet error rates.

Innovation Solution

A method and system that utilize transmitter EVM values to modify beamforming parameters and compensate for transmitter-induced noise, enabling equal SNR levels across signals through geometric mean decomposition (GMD) or uniform channel decomposition (UCD) methods, allowing for effective nulling of noise during transmission and reception.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If conventional MIMO receivers decode information without compensating for transmitter-induced noise, then the decoding process is simple, but bit error rates and packet error rates increase

Engineering Contradiction:

Improvedecoding process simplicityVSAvoidbit error rate and packet error rate

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent implements feedback mechanisms where the receiver estimates transmitter-induced noise characteristics and feeds this information back to adjust the decoding process. The receiver computes noise covariance matrices and uses these to modify the decoding operations, thereby compensating for transmitter impairments while maintaining reasonable operational complexity.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent changes the parameters of the decoding process by introducing noise compensation factors and modified weighting matrices that account for transmitter-induced noise. These parameter modifications allow the receiver to adjust its operation based on estimated noise characteristics, improving error rates without fundamentally changing the decoding architecture.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If stringent circuitry requirements are imposed to maintain acceptable error rates, then reliability improves, but device complexity and cost increase

Engineering Contradiction:

Improvebit error rate and packet error rateVSAvoidcircuitry complexity and cost

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent substitutes complex hardware circuitry with signal processing algorithms that run on standard processors. Instead of using expensive dedicated hardware to compensate for noise, the invention employs computational methods including matrix operations and iterative decoding algorithms that can be implemented on general-purpose processors, thereby reducing device complexity while maintaining reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The system performs self-compensation by having the receiver estimate its own noise characteristics and automatically adjust decoding parameters. This self-service approach eliminates the need for external complex correction circuits, as the system uses its own received signal information to generate compensation mechanisms through software algorithms.

Inventive Principle:

Principle #25Self-service

3Device complexity

If transmitter-induced noise is not compensated, then the transmission system is simple, but performance losses occur due to errors in decoding

Engineering Contradiction:

Improvetransmission system complexityVSAvoiddecoding accuracy

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies preliminary actions by having the receiver pre-compute noise covariance matrices and prepare compensation factors before the actual decoding process. These pre-calculated parameters are then used during decoding to compensate for transmitter-induced noise, thereby improving accuracy without adding complex real-time processing during transmission.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS7664200B2Method and system for minimizing effects of transmitter impairments in multiple input multiple output (MIMO) beamforming communication systems

Publication Date: 2010.02.16 BELL NORTHERN RESEARCH LLC

AI summary

Aspects of a method and system for minimizing effects of transmitter impairments in multiple input multiple output (MIMO) beamforming communication systems are presented. In one aspect of a system for minimizing effects of transmitter impairments, a MIMO transmitter may enable nulling of transmitter-induced noise by adjusting at least a portion of a plurality of signals transmitted based on a transmitter error vector magnitude (EVM). The transmitter may enable transmission of the plurality of signals subsequent to the nulling. In another aspect of a system for minimizing effects of transmitter impairments a MIMO receiver may enable nulling of transmitter-induced noise contained in a plurality of received signals based on a transmitter EVM. Each of the plurality of received signals may include information contained in a plurality of spatial streams. The receiver may enable detecting estimated values for the information contained in the plurality of spatial streams based on the nulling.