Variable FEC Selection Using Eye Monitoring in Optical Links
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Solution Overview
Problem
Existing optical communication systems face challenges in dynamically adjusting forward error correction (FEC) codes to optimize error correction performance based on changing line quality and communication standards, which can lead to suboptimal error correction and increased power consumption.
Innovation Solution
A photonic integrated circuit (PIC) and electrical integrated circuit (EIC) system that includes error correction circuitry capable of selecting and switching between different FEC codes, such as Reed-Solomon, BCH, Hamming, Turbo, and LDPC codes, based on line quality monitoring and communication standards, using a combination of programmable and non-programmable logic to adjust error correction strength according to the bit error rate and data transmission requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single strong FEC code is used to ensure error correction performance under all conditions, then reliability is improved, but power consumption and latency increase
Solution Approach 1:
The system dynamically switches between different FEC codes (RS(255,239), BCH(255,223), Hamming(255,221)) based on real-time line quality monitoring. When line quality is good, a weaker FEC code is used to reduce power consumption and latency. When line quality degrades, a stronger FEC code is activated to maintain reliability. This dynamic adaptation resolves the contradiction by making error correction performance conditional rather than constant.
Solution Approach 2:
The system changes the parameters of error correction by selecting different FEC codes with varying correction strengths and overhead ratios. Each FEC code has different computational complexity and power requirements. By adjusting which FEC code is active based on line quality metrics, the system optimizes the balance between reliability and power consumption.
2Adaptability or versatility
If multiple FEC codes are supported for adaptive selection, then adaptability is improved, but device complexity increases
Solution Approach 1:
The error correction functionality is segmented into multiple independent FEC code implementations (RS, BCH, Hamming), each capable of operating independently. A selector mechanism chooses which segment to activate based on line quality. This segmentation allows adaptability without requiring all codes to operate simultaneously, managing complexity through modular design.
Solution Approach 2:
The error correction circuitry is designed with multi-functionality to support multiple FEC code types within a single system. Rather than requiring separate dedicated hardware for each FEC standard, the system integrates multiple codes that can share common infrastructure (such as the line quality monitor and selector logic), achieving universality while controlling complexity.
3Reliability
If stronger FEC codes are used to correct higher bit error rates, then reliability is improved, but latency increases
Solution Approach 1:
The system dynamically adjusts the strength of error correction applied based on real-time line quality assessment. When line quality is excellent, minimal or no FEC processing is applied, reducing latency. When line quality deteriorates, stronger FEC codes are activated to maintain reliability. This dynamic approach ensures that latency is only increased when necessary for reliability.
Solution Approach 2:
The system applies partial error correction action by selecting FEC codes with appropriate overhead ratios matched to actual line conditions. Rather than always applying maximum error correction capability, the system uses just enough correction strength needed for current conditions, avoiding excessive processing latency while maintaining sufficient reliability.
Data Source
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AI summary
A system includes an encoding circuit, a line quality monitor circuit, and a controller circuit. The encoding circuit generates a first data signal indicating encoded data using a first forward error correction code. The line quality monitor circuit generates an indication of a line quality of a second data signal using an eye monitor circuit that monitors the second data signal. The controller circuit causes the encoding circuit to generate encoded data in the first data signal using a second forward error correction code in response to a change in the indication of the line quality of the second data signal.