Delta-Sigma Modulation with Learned Path Distortion Compensation

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Solution Overview

Problem

In radio communication systems using delta-sigma modulation and Radio over Fiber (RoF) technology, transmission path distortion leads to spectral leakage and deteriorated signal quality, which existing technologies struggle to accurately compensate for.

Innovation Solution

A delta-sigma modulation apparatus that performs delta-sigma modulation on an input signal, learns parameters for a transmission path distortion model including a mixture model and a filter structure, and uses this model to suppress distortion in the transmitted signal, thereby improving signal quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If delta-sigma modulation is used to reduce DAC resolution and power consumption, then power consumption is reduced, but transmission path distortion occurs causing spectral leakage

Engineering Contradiction:

Improvepower consumptionVSAvoidtransmission path distortion

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by performing distortion compensation processing on the input signal before delta-sigma modulation. The compensation filter pre-corrects the signal characteristics that would otherwise cause spectral leakage after modulation, thereby preventing the harmful effect before it occurs while maintaining the power consumption benefits of delta-sigma modulation

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces a compensation filter as an intermediary component between the input signal and the delta-sigma modulator. This intermediary processes the signal to counteract transmission path distortion, allowing the system to maintain both low power consumption and high signal quality

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If existing distortion compensation methods are used, then some distortion is reduced, but spectral leakage and signal quality deterioration persist

Engineering Contradiction:

Improvesignal qualityVSAvoidspectral leakage

Core Design Contradiction:

ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent applies parameter changes by dynamically adjusting the compensation filter coefficients based on the specific characteristics of the input signal and transmission path. This adaptive approach allows the system to effectively compensate for distortion across different operating conditions, thereby reducing spectral leakage and improving signal quality beyond what fixed compensation methods achieve

Inventive Principle:

Principle #35Parameter changes

3Speed

If high-speed DAC is used to achieve high-speed communication, then communication speed is improved, but power consumption increases

Engineering Contradiction:

Improvecommunication speedVSAvoidpower consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent substitutes the traditional high-speed DAC approach with a digital signal processing approach using compensation filters and delta-sigma modulation. This replacement maintains high-speed communication capabilities while significantly reducing power consumption by avoiding the need for high-speed analog conversion

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS20250132769A1Delta-sigma modulation apparatus, delta-sigma modulation method and recording medium

Publication Date: 2025.04.24 NEC CORP

AI summary

A delta-sigma modulation apparatus performs delta-sigma modulation on a first signal as an input signal and outputs a second signal; learns a parameter for a transmission path distortion model using the second signal and a third signal generated through a transmission path of the second signal; inputs the second signal to the transmission path distortion model and outputs a fourth signal that is an approximated value of a signal which is generated through at least part of the transmission path of the second signal, and performs the delta-sigma modulation on the first signal using the fourth signal and outputs the second signal.