Rate-Adaptive Optical FEC Overhead Without Hardware Changes
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Solution Overview
Problem
Existing FEC sub-systems for optical fiber communication systems lack flexibility in error correction capabilities, as they cannot adjust error correction overhead without changing hardware, which is inadequate for varying bandwidth demands and error tolerance requirements.
Innovation Solution
A rate-adaptive FEC encoder and decoder system that adjusts the number of known symbols in a codeword to achieve flexible overhead error correction, allowing for varying error correction capabilities without requiring hardware changes, by generating codewords based on information and data symbols with a fixed number of parity symbols and expanding reliability values for decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of parity symbols is increased to improve error correction capability, then reliability is improved, but device complexity increases due to hardware changes
Solution Approach 1:
The patent implements dynamic FEC overhead adjustment by allowing the FEC encoder to vary the number of parity symbols based on channel conditions and service requirements. The system transitions from static hardware-configured FEC to a dynamic software-controlled FEC implementation, enabling the overhead ratio to be adjusted without physical hardware changes. This resolves the contradiction by providing flexible reliability adjustment without proportionally increasing hardware complexity.
Solution Approach 2:
The patent changes the parameter of FEC overhead ratio from a fixed hardware parameter to a variable software-controlled parameter. By implementing FEC in software or firmware rather than fixed hardware, the system can dynamically adjust the number of parity symbols and code rate according to varying channel conditions and service requirements, achieving improved reliability when needed without permanently increasing hardware complexity.
2Device complexity
If fixed hardware FEC is used to maintain simplicity, then device complexity is reduced, but adaptability deteriorates as varying error correction capabilities cannot be provided
Solution Approach 1:
The patent implements a universal FEC sub-system that can perform multiple FEC functions with different overhead ratios using the same hardware platform. The FEC encoder is designed to support variable code rates and overhead configurations through software control, allowing a single hardware implementation to serve multiple services with different error correction requirements. This resolves the contradiction by achieving multi-functionality without multiplying hardware complexity.
Solution Approach 2:
The patent introduces dynamic configurability to the FEC sub-system, allowing the overhead ratio and code rate to be adjusted in real-time based on channel conditions and service requirements. This dynamic capability enables the same hardware to adapt to varying error correction needs, achieving versatility without requiring multiple fixed hardware configurations.
3Reliability
If overhead ratio is increased to improve error correction for varying bandwidth demands, then reliability is improved, but loss of information increases due to more redundant symbols
Solution Approach 1:
The patent implements dynamic adjustment of the FEC overhead ratio based on real-time channel conditions and service requirements. When channel conditions are good or bandwidth demand is high, the overhead is reduced to minimize information loss. When channel conditions deteriorate or error correction needs increase, the overhead is increased to improve reliability. This dynamic approach resolves the contradiction by optimizing the trade-off between reliability and information overhead rather than using a fixed high overhead.
Data Source
AI summary
In some embodiments, an apparatus includes an optical transceiver which includes a rate-adaptive forward error correction (FEC) encoder and a rate-adaptive FEC decoder. The rate-adaptive FEC encoder is configured to adjust a number of a set of known symbols associated with a codeword to achieve rate adaption. A length of the codeword is fixed. The rate-adaptive FEC encoder is configured to generate the codeword based on (1) a set of information symbols including the set of known symbols and a set of data symbols, and (2) a fixed number of a set of parity symbols generated using information symbols. The rate-adaptive FEC decoder is configured to receive a set of reliability values associated with a channel word, and expand the set of reliability values to produce an expanded set of reliability values. The rate-adaptive FEC decoder is further configured to decode the expanded set of reliability values.