DPD Feedback Path Compensation for Multipath Distortion

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Solution Overview

Problem

Multipath distortions along the transmission path degrade the performance of digital pre-distortion (DPD) linearization in wireless communication systems, as they cause amplitude and delay variations in feedback signals, limiting the effectiveness of DPD linearization in maintaining signal quality and adjacent channel power ratio (ACPR).

Innovation Solution

A method of multipath compensation is introduced, which includes a transmission multipath compensation filter and feedback multipath compensation filter using finite impulse response (FIR) filters to correct for the effects of multipath signals and reflections, ensuring accurate feedback for the DPD engine to generate predistorted signals that reverse non-linearity in power amplifiers and other components, thereby improving DPD linearization performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If digital pre-distortion linearization is used to improve amplifier linearity, then adjacent channel power ratio is improved, but multipath distortions degrade the linearization performance

Engineering Contradiction:

Improvesignal qualityVSAvoidmultipath distortions

Core Design Contradiction:

Manufacturing precisionVSObject-affected harmful factors

Solution Approach 1:

The system separates multipath compensation from DPD linearization by introducing distinct compensation filters for transmitting and feedback paths. This segmentation allows independent optimization of linearization and multipath effects, resolving the degradation caused by multipath distortions while maintaining DPD performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Multipath compensation filters are introduced as intermediary components between the DPD engine and the power amplifier/feedback path. These filters act as mediators that remove multipath distortions before signals reach the DPD processing, preventing degradation of linearization performance.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If feedback signals are used for DPD adaptation, then linearization performance is improved, but multipath reflections cause amplitude and delay variations that limit effectiveness

Engineering Contradiction:

ImproveDPD linearization performanceVSAvoidfeedback signal accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The feedback multipath compensation filter extracts and removes multipath distortion components from feedback signals before they are used for DPD adaptation. By taking out the harmful multipath reflections, the system recovers accurate feedback signals for reliable DPD linearization.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system implements a feedback mechanism where compensated feedback signals are used to adapt DPD coefficients. The feedback path includes multipath compensation that ensures the adaptation process uses clean, accurate signals, improving the reliability of DPD linearization despite presence of multipath reflections.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS8982995B1Communication device and method of multipath compensation for digital predistortion linearization

Publication Date: 2015.03.17 MICROELECTRONICS TECH INC

AI summary

A method of multipath compensation for digital pre-distortion (DPD) linearization suppresses linear distortion caused by reflected signals and distortion in transmitting and receiving paths. Reflection suppression suppresses effects of the linear distortion on the transmitting and receiving paths.