Frequency-Domain Amplitude Normalization for PLC Symbol Synchronization

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Solution Overview

Problem

In multi-carrier systems, particularly power line communication (PLC) environments, impulsive noise and narrow band interference significantly degrade synchronization performance, making it challenging for receivers to accurately synchronize with received signals.

Innovation Solution

The implementation of frequency-domain amplitude normalization, where digital samples are processed using a Fast Fourier Transform (FFT) to generate complex frequency components, which are then normalized and correlated with frequency-domain reference symbols, effectively reducing the impact of noise and interference on synchronization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If time domain correlation is used for synchronization, then the synchronization process is simple to implement, but synchronization performance degrades significantly in the presence of impulsive noise and narrow band interference

Engineering Contradiction:

Improveease of implementationVSAvoidsynchronization performance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces time-domain correlation (mechanical signal processing approach) with frequency-domain correlation using FFT-based methods. This substitution transforms the synchronization problem from the time domain to the frequency domain, where interference can be better handled through amplitude normalization before correlation, thereby improving reliability without significantly increasing implementation complexity

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent applies amplitude normalization to the frequency components before performing correlation. This parameter change (normalizing the amplitude of each frequency component) prevents impulsive noise and narrow band interference from dominating the correlation process, thereby improving synchronization performance in harsh PLC environments

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If frequency-domain amplitude normalization is applied, then symbol synchronization accuracy improves, but computational complexity increases due to FFT processing

Engineering Contradiction:

Improvesynchronization accuracyVSAvoidcomputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces direct time-domain correlation with an FFT-based frequency-domain approach. While FFT adds computational steps, it enables amplitude normalization that significantly improves synchronization accuracy in noisy environments. The increased computational complexity is justified by the substantial improvement in measurement precision for symbol boundary detection

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent segments the frequency spectrum into individual subcarriers and applies amplitude normalization to each frequency component separately. This segmentation allows selective processing of frequency components, improving synchronization accuracy by preventing dominant interferers from overwhelming the correlation process, while managing computational complexity through efficient FFT implementation

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances symbol synchronization accuracy and performance by improving correlation values, allowing for more reliable detection of symbol boundaries and synchronization, even in harsh PLC channels.

Implementation Method 1

digital samples are processed using a Fast Fourier Transform (FFT) to generate complex frequency components

Methodology Applied

Scientific EffectFast Fourier Transform:

Data Source

PatentUS9100261B2Frequency-domain amplitude normalization for symbol correlation in multi-carrier systems

Publication Date: 2015.08.04 NXP USA INC

AI summary

Methods and systems are disclosed for frequency-domain amplitude normalization for symbol correlation in multi-carrier communication systems. Digital samples associated with input signals received from a communication medium are processed using a Fast Fourier Transform (FFT) to generate complex frequency components. Each complex frequency component is normalized with respect to its amplitude, and the frequency-domain, amplitude-normalized frequency components are multiplied with frequency components for reference symbol(s) to generate frequency-domain correlation values. These frequency-domain correlation values are analyzed to determine if a correlation exists between the amplitude-normalized frequency components and the predetermined reference frequency components. A correlation detection output is then generated that indicates whether or not a symbol synchronization was achieved. The disclosed embodiments are particularly useful for symbol correlation in received signals for power line communication (PLC) systems.