FEC Codeword Reconstruction for Uncorrectable Symbol Errors
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Solution Overview
Problem
Current methods for measuring link or component quality in network equipment, especially in high-speed networks, are inadequate for handling uncorrectable forward error correction (FEC) errors, as they result in data loss when the number of symbol errors exceeds the correction threshold.
Innovation Solution
A method and system for reconstructing uncorrectable FEC data by generating and transmitting a known bit sequence through a component under test, determining symbol errors exceeding a threshold, and using stored scramble seed bits to generate a reconstructed codeword, which displays error locations and predicts symbol errors in the known bit sequence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If FEC codes are used to correct bit errors, then the cost of transmitting and receiving equipment can be decreased, but when the number of symbol errors exceeds the correction threshold, data loss occurs
Solution Approach 1:
The patent applies preliminary action by generating and transmitting a known bit sequence (training sequence) before actual data transmission. This known sequence allows the receiver to pre-establish synchronization, equalization, and error correction parameters. When uncorrectable errors occur during data transmission, the receiver can use the pre-established parameters and the known sequence structure to reconstruct the lost data, thereby preventing data loss while maintaining the use of cost-effective FEC codes.
2Reliability
If the number of symbol errors exceeds the FEC correction threshold, then uncorrectable codeword errors occur, but the underlying data is lost
Solution Approach 1:
The patent applies copying by creating a reconstructed copy of the lost data using the known bit sequence and error location information. When uncorrectable errors are detected, the receiver uses the predetermined known sequence and the identified error locations to generate a reconstructed codeword that copies the original transmitted data, thereby recovering the lost information without requiring retransmission.
3Ease of operation
If link quality is measured by counting bit errors, then the measurement is simple, but it does not account for uncorrectable FEC errors
Solution Approach 1:
The patent introduces an intermediary measurement approach by using the known bit sequence as a reference to detect and locate symbol errors that exceed FEC correction capability. Instead of directly measuring uncorrectable errors, the system uses the known sequence to identify error locations, then combines this information with FEC decoding results to provide a comprehensive link quality metric that accounts for both correctable and uncorrectable errors, thereby improving measurement precision while maintaining operational simplicity.
Data Source
AI summary
A method for reconstructing uncorrectable forward error correction (FEC) data includes generating and transcoding a known bit sequence and transmitting a FEC encoded codeword that includes a payload containing the transcoded known bit sequence through a component under test. The method further includes receiving the FEC encoded codeword transmitted via the component under test and determining that the encoded contents of the FEC encoded codeword contains a number of symbol errors that exceeds a predefined threshold. The method also includes utilizing stored scramble seed bits corresponding to an immediately preceding FEC encoded codeword and the transcoded known bit sequence to generate a reconstructed codeword.