Multi-Mode Channel Decoder Using Implicit FEC Mode Detection

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Solution Overview

Problem

Existing channel coding systems for audio data face challenges in efficiently switching between different forward error correction (FEC) modes due to the need for explicit mode signaling, which reduces data rate and is vulnerable to transmission errors, especially in wireless networks with varying signal strength.

Innovation Solution

A channel decoder and encoder system that uses implicit mode signaling through a decoding mode detector, which performs two decoding operations to determine the FEC mode efficiently, ensuring error resilience and reducing the need for explicit mode transmission by applying a coloration sequence and syndrome calculations to identify the correct decoding mode.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If explicit mode signaling is used to indicate FEC mode, then the decoder can correctly identify the coding mode, but the data rate is reduced and the signaling is vulnerable to transmission errors

Engineering Contradiction:
ImproveFEC mode identification reliabilityVSAvoiddata rate
Core Design Contradiction:
ReliabilityVSLoss of information

Solution Approach 1:

The patent extracts the FEC mode information from the audio data frame itself by utilizing the mode-dependent transformation properties of the encoded data. Instead of adding separate signaling bits, the decoder performs trial decodings with different FEC modes and identifies the correct mode by detecting which transformation produces valid code words. This removes the need for explicit mode signaling while maintaining reliability.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The audio data frame carries its own FEC mode information through its encoded structure. The decoder uses the data's inherent properties (code word validity under different transformations) to self-identify the correct FEC mode without external signaling. The data serves both as the encoded information and as the carrier of mode identification information.

Inventive Principle:
Principle #25Self-service

2Reliability

If explicit mode signaling is used to indicate FEC mode, then the decoder can correctly identify the coding mode, but the signaling is exposed to transmission errors

Engineering Contradiction:
ImproveFEC mode identification accuracyVSAvoidtransmission errors on signaling
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent removes mode signaling from the vulnerable separate channel and extracts it directly from the encoded data structure. The mode identification is derived from the data's own transformation properties rather than from separate signaling bits that could be corrupted independently. This integration protects against transmission errors affecting the mode indication.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The decoder uses a feedback mechanism by performing trial decodings and checking whether the transformed data produces valid code words. The correctness of mode identification is verified through this feedback loop - if the transformation yields valid code words, the mode is confirmed correct. This self-verification protects against erroneous mode detection.

Inventive Principle:
Principle #23Feedback

3Reliability

If multiple configuration parameters are signaled for UEP, then the error protection can be optimized for different sub-frames, but the in-band configuration parameters reduce the data rate and require separate protection

Engineering Contradiction:
Improveerror protection optimizationVSAvoidconfiguration parameters signaling
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts UEP configuration information from the encoded data structure itself rather than signaling it separately. Different FEC modes provide different levels of protection for different portions of the data, and the decoder identifies the appropriate mode through trial decoding and validation. This removes the need for separate configuration parameter signaling while maintaining UEP capabilities.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The FEC mode selection provides a universal mechanism that simultaneously achieves error protection optimization and mode identification. A single mode selection determines both the error correction capability and the data rate characteristics, eliminating the need for multiple separate configuration parameters. The same transformation that provides error protection also carries the mode identification information.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4239924B1Decoder and decoding method for multi-mode channel coding with scrambling according to selected mode
Publication Date: 2026.04.22 FRAUNHOFER GESELLSCHAFT ZUR FORDERUNG DER ANGEWANDTEN FORSCHUNG EV
  • EP4239924B1 patent drawingFigure 1~2
  • EP4239924B1 patent drawingFigure 3
  • EP4239924B1 patent drawingFigure 4

AI summary

A channel decoder for channel decoding at least one transmitted code word, comprising: a colorator for applying at least one coloration sequence to the at least one transmitted code word or to an error corrected at least one transmitted code word to obtain at least one colored code word, wherein the coloration sequence is such that at least one bit of the code word is changed by the application of the at least one coloration sequence, and wherein the at least one coloration sequence is associated to a certain decoding mode as a specific coloration sequence; a redundancy decoder for redundancy decoding the at least one colored code word to obtain a decoded output code word; and a decoding mode detector (26) for generating a decoding mode indicator indicating the certain decoding mode to be used by the redundancy decoder to obtain the decoded output code word, wherein the decoding mode indicator is associated to the at least one coloration sequence as the specific coloration sequence used for the coloration of the transmitted code word.