Frequency Hopping Interference Detection via Decoder Codeword Metrics

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Solution Overview

Problem

Frequency-hopping communication systems face challenges in maintaining transmission quality due to varying interference levels across channels, which can degrade the overall communication system performance.

Innovation Solution

The method involves decoding multiple code blocks into codewords using error control coding and determining codeword metrics such as errors corrected, bits flipped, retransmissions, and error correction iterations. These metrics are used to infer channel metrics, which help in assessing channel reliability and mitigating interference by adjusting channel usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If frequency hopping is used to resist narrowband interference, then communication system reliability is improved, but transmission quality varies across channels due to interference

Engineering Contradiction:
Improvecommunication system reliabilityVSAvoidtransmission quality consistency
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent implements feedback by measuring codeword metrics (error counts, iteration counts) from decoded packets and using these measurements to infer channel quality. The system continuously monitors decoding performance and adjusts channel usage based on inferred quality metrics, creating a closed-loop feedback mechanism that adapts to varying interference conditions while maintaining reliable communication

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The patent applies dynamics by making the channel hopping pattern adaptive rather than static. The frequency hopping sequence dynamically adjusts based on inferred channel quality metrics, allowing the system to avoid poor-quality channels and concentrate transmissions on better channels, thereby maintaining consistent transmission quality across varying interference conditions

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If direct signal-to-noise ratio measurement is used to assess channel quality, then channel quality measurement is straightforward, but the system cannot dynamically adapt channel usage effectively

Engineering Contradiction:
Improvechannel quality measurement simplicityVSAvoiddynamic channel adaptation capability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent introduces an intermediary approach by using codeword metrics from the decoding process as a mediator between the received signal and channel quality assessment. Instead of directly measuring signal-to-noise ratio, the system measures decoding performance metrics (error counts, iteration counts) that indirectly reflect channel quality, enabling both simple measurement and effective dynamic adaptation

Inventive Principle:
Principle #24Intermediary (Mediator)

3Device complexity

If channel quality is not monitored, then system complexity is reduced, but transmission quality degrades due to poor channel selection

Engineering Contradiction:
Improvesystem complexityVSAvoidtransmission quality
Core Design Contradiction:
Device complexityVSManufacturing precision

Solution Approach 1:

The patent implements self-service by having the decoding process itself generate the quality metrics needed for channel assessment. The codeword metrics (error counts, iteration counts) are naturally produced during normal decoding operations, requiring no additional measurement hardware or complex processing. The system uses these self-generated metrics to infer channel quality and adapt channel usage, achieving effective quality monitoring with minimal added complexity

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP4170944B1Frequency hopping interference detection using decoder codeword metrics
Publication Date: 2025.05.14 L3HARRIS TECH INC
  • EP4170944B1 patent drawingFigure 1
  • EP4170944B1 patent drawingFigure 2
  • EP4170944B1 patent drawingFigure 3

AI summary

A method for mitigating interference in a frequency hopping channel system based on codeword metrics obtained during decoding of codewords. The method includes decoding a plurality of codewords using a particular error control coding method. Each of the plurality of codewords includes portions received from plurality of channels in the frequency hopping channel system. For each decoded codeword, one or more codeword metrics are obtained based on the cost of correcting errors during decoding of the plurality of codewords. Based on the codeword metrics, one or more channel metrics are inferred. Based on the inferred one or more channel metrics, a reliability metric of a particular channel is reduced, or incoming symbols received from the particular channel are ignored during decoding.