Spatially Coupled GEL Codes for Low-Latency FEC Decoding

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Solution Overview

Problem

Existing spatially coupled forward error correction (FEC) codes face limitations in achieving low-latency, high-throughput, and high-rate applications with a low error-floor and low-complexity decoding procedures, particularly in optical communications.

Innovation Solution

The use of generalized error location (GEL) codes as component codes in spatially coupled FEC constructions, enabling low-latency, high-throughput, and high-rate applications with a low error-floor and low-complexity decoding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional spatially coupled FEC codes are used, then high throughput is achieved, but latency increases and error-floor remains high

Engineering Contradiction:
ImprovethroughputVSAvoidlatency
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The patent segments the data stream into blocks and applies spatial coupling across multiple component codes arranged in a staircase pattern. This segmentation allows parallel processing of different code blocks, reducing overall decoding latency while maintaining high throughput through efficient resource utilization across multiple coding layers.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent introduces a spatial dimension by arranging component codes in a two-dimensional staircase structure rather than a single sequence. This dimensional transformation enables simultaneous processing of multiple code blocks across different spatial positions, achieving low latency without sacrificing throughput by utilizing parallel decoding paths.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

2Productivity

If conventional spatially coupled FEC codes are used, then high throughput is achieved, but error-floor level remains high

Engineering Contradiction:
ImprovethroughputVSAvoiderror-floor
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent employs a composite coding structure combining multiple component codes (including GEL codes and other FEC codes) in a staircase configuration. This composite approach integrates the strengths of different coding schemes, achieving both high throughput and low error-floor by leveraging the error correction capabilities of diverse code types working together in parallel.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent changes key parameters of the spatially coupled code construction, specifically using GEL codes with optimized error correction capabilities and adjusting the staircase structure parameters. These parameter modifications enable the system to achieve both high throughput and reduced error-floor by optimizing the balance between code strength and decoding efficiency.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If complex decoding procedures are used to reduce error-floor, then reliability improves, but device complexity increases

Engineering Contradiction:
Improveerror-floorVSAvoiddecoding complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the error correction task across multiple simpler component codes rather than using a single complex code. Each component code in the staircase structure can be decoded independently with relatively simple procedures, yet the collective effect achieves low error-floor through the coordinated action of multiple decoding stages.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses a composite of different code types including GEL codes known for their low-complexity decoding. By incorporating codes with inherently simple decoding procedures into the staircase structure, the system achieves reliable error correction without requiring complex decoding algorithms, maintaining low device complexity while improving reliability.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP4062540B1Spatially coupled forward error correction encoding method and device using generalized error locating codes as component codes
Publication Date: 2025.08.27 HUAWEI TECH CO LTD
  • EP4062540B1 patent drawingFigure 1
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  • EP4062540B1 patent drawingFigure 3

AI summary

The present disclosure provides an encoding and decoding device implementing an improved forward error correction, FEC, coding/ decoding method. In particular, the encoding device is configured to encode a stream of data symbols using a spatially coupled code (e.g. staircase codes, braided block codes or continuously interleaved block codes), wherein at least one generalized error location, GEL, code is used as a component code of the spatially coupled code. Accordingly, the decoding device is configured to decode a sequence of encoded symbol blocks using a spatially coupled code, wherein at least one GEL code is used as a component code of the spatially coupled code. Thereby, a suitable spatially coupled FEC code that allows for very low-latency, high-throughput, high-rate applications with a low-complexity decoding procedure, and allows for mitigation of the error-floor, is designed.