OFDM Co-Channel Interference Detection via Time-Domain Signal Processing

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Solution Overview

Problem

Existing OFDM systems face challenges in effectively detecting and mitigating co-channel interference (CCI) due to its severe impact on signal precision and SNR, particularly in the frequency domain, which limits system efficiency.

Innovation Solution

A method and circuit for detecting CCI in the time domain using scattered pilot time-domain interpolation, differential, and block average operations to generate error sequences, followed by sliding averages and threshold comparisons to determine interference, allowing for precise detection of both static and dynamic interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If CCI detection is implemented in the frequency domain using known parameters, then the detection can be performed with available information, but the detection accuracy is insufficient because CCI severely affects parameter estimation in the time domain

Engineering Contradiction:

ImproveCCI detection accuracyVSAvoidparameter estimation reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent inverts the conventional approach by performing CCI detection in the time domain instead of the frequency domain. It uses time-domain signal characteristics and operations (differential, block average, sliding average) to detect CCI, thereby avoiding the problem where CCI corrupts frequency-domain parameter estimation.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent performs preliminary time-domain operations (differential operation, block average operation, sliding average operation) on the received signal before making CCI detection decisions. These preliminary processing steps extract useful time-domain characteristics that are less affected by CCI, enabling more accurate detection.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If conventional CCI detection methods are used, then the system can operate with standard processing, but the system efficiency heavily decreases due to signal damage and SNR loss

Engineering Contradiction:

Improvesystem efficiencyVSAvoidsignal-to-noise ratio loss

Core Design Contradiction:

ProductivityVSLoss of energy

Solution Approach 1:

The patent replaces conventional frequency-domain detection mechanisms with time-domain processing operations. By substituting the detection domain from frequency to time, the system achieves better CCI detection performance and maintains higher signal quality, thereby improving overall system efficiency and reducing SNR loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If frequency-domain CCI detection is performed, then the detection can be implemented with existing parameters, but it can barely work for the receiving end because CCI affects time-domain parameter estimation

Engineering Contradiction:

Improvedetection implementation easeVSAvoidCCI detection precision

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

Inventive Principle:

Principle #13The other way round (Inversion)

Data Source

PatentEP3163822B1Method for detecting co-channel interference and circuit using the same

Publication Date: 2018.08.01 ALI CORP

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AI summary

Disclosed are a method for detecting the co-channel interference and a method using the same. The method is used in a receiving device, having a plurality of symbols and executing a channel estimating operation for the OFDM signal, in an OFDM system. The method comprising: respectively capturing a plurality of time-domain interpolation results related to each symbol, after executing a scattered pilot time-domain interpolation during the channel estimating operation (S101); respectively executing a differential operation and a block average operation for the time-domain interpolation results of each symbol, to generate a first error sequence related to each symbol and to correspondingly obtain an average of all elements in the first error sequence as an error average of each code (S103); sequentially executing a sliding average operation for the first error sequence of each symbol based on a moving index of a sliding window, to obtain a first vector related to each symbol and to correspondingly obtain the maximum among all elements in the first vector as an abnormal output related to each code (S105); and determining whether the OFDM signal is affected by the co-channel interference based on the abnormal output and the error average of each code (S 107).