Clustering-Based Frequency Offset Determination in Wireless Signals

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Solution Overview

Problem

Existing methods for determining frequency offset in wireless communication are not consistently accurate due to variations in calculated values, leading to signal distortion and reduced accuracy in signal identification.

Innovation Solution

A clustering-based method that determines a constellation diagram for a received signal, corrects it using multiple frequency offset estimates, clusters signal points, and calculates the area of the signal region to identify the frequency offset corresponding to a minimum area, eliminating the need to calculate the argument of the complex signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If the existing approach of calculating the argument of a complex signal is used to determine frequency offset, then the method is simple to implement, but the calculated value of frequency offset varies depending on the discrete number n, resulting in inconsistent accuracy

Engineering Contradiction:

ImproveEase of implementationVSAvoidAccuracy of frequency offset estimation

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent divides the frequency offset determination process into multiple discrete steps: generating N different frequency offset estimates, correcting the constellation diagram for each estimate, clustering signal points, and calculating signal region areas. This segmentation allows systematic evaluation of multiple candidates to achieve consistent accuracy while maintaining implementation simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent changes the evaluation parameter from the argument of a complex signal to the area of the signal region in the constellation diagram. By using the area metric combined with clustering analysis, the method achieves stable and consistent frequency offset estimation that is independent of the discrete number n, thereby improving measurement precision.

Inventive Principle:

Principle #35Parameter changes

2Measurement precision

If multiple frequency offset estimates are tested with constellation diagram correction and clustering, then the accuracy and stability of frequency offset estimation is improved, but the computational complexity increases

Engineering Contradiction:

ImproveAccuracy of frequency offset estimationVSAvoidComputational complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent generates N different frequency offset estimates and tests each one, which is more than the single estimate approach. However, by using the area of signal region as a clear evaluation criterion, the method efficiently identifies the correct frequency offset without requiring exhaustive testing, thus achieving high accuracy with manageable computational complexity.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The patent replaces complex signal processing operations (calculating arguments of complex signals) with geometric operations (calculating areas of signal regions in constellation diagrams). This substitution simplifies the computational process while improving the reliability and consistency of frequency offset estimation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If the argument calculation method is used, then the implementation is straightforward, but the frequency offset value varies with discrete number n causing signal distortion

Engineering Contradiction:

ImproveEase of operationVSAvoidStability of frequency offset value

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The patent uses the constellation diagram itself and its geometric properties (area of signal region) to determine the frequency offset, rather than relying on external calculations that vary with discrete parameters. The method is self-contained and produces consistent results independent of the discrete number n, thereby improving reliability.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

Instead of calculating frequency offset directly from signal parameters that vary with n, the patent inverts the approach by testing multiple frequency offset estimates and evaluating them based on the area metric. The correct frequency offset is identified as the one that minimizes the signal region area, providing stable and reliable results.

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentUS11218354B2Clustering-based frequency deviation determination and elimination method and device, and electronic apparatus

Publication Date: 2022.01.04 BEIJING UNIV OF POSTS & TELECOMM

AI summary

Clustering-based methods, apparatuses for frequency offset determination and elimination and electronic devices are disclosed. The clustering-based method for frequency offset determination includes: determining a constellation diagram for a received signal; determining N different values within a preset frequency interval, as N frequency offset estimates for a frequency offset of the received signal; for each of the frequency offset estimates, correcting the constellation diagram based on the frequency offset estimate to obtain a corrected constellation diagram, clustering signal points on the corrected constellation diagram, and calculating an area of a signal region in the corrected constellation diagram after clustering; and determining a frequency offset estimate corresponding to a signal region with a minimum area as a value of the frequency offset. The embodiments of the present invention can improve the accuracy and stability of the calculated value of the frequency offset.