64B/66B OAM Encoding via FEC Parity Sync-Header Patterns
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Solution Overview
Problem
Existing 64B/66B line coding systems in PONs face challenges in carrying OAM information without diminishing the error correcting capacity, particularly in error-prone environments like EPONs, where the inclusion of OAM data can lead to incomplete codewords and reduced error correction capabilities.
Innovation Solution
Incorporating a single OAM bit into each FEC codeword, which determines the parity sync-header patterns, allowing for the transmission of OAM information while maintaining the error correcting capacity by using two predetermined bit patterns (00, 11, 11, 00) and (11, 00, 00, 11) to minimize disruption to payload and parity bits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If OAM information is added to 64B/66B line coding systems, then OAM transmission capability is improved, but error correction capacity is reduced
Solution Approach 1:
The patent merges OAM information transmission with FEC codeword structure by incorporating a single OAM bit into each FEC codeword. This combines two separate functions (OAM signaling and error correction) into a unified code structure, allowing both purposes to be achieved simultaneously without requiring separate transmission channels that would consume additional bandwidth or compromise error correction resources.
Solution Approach 2:
The FEC codeword structure is designed to serve multiple functions: it simultaneously carries payload data, provides error correction capability through parity bits, and transmits OAM information through a dedicated bit position. This multi-functional design eliminates the need for separate OAM channels and ensures that error correction resources are not diminished by OAM transmission requirements.
2Loss of information
If OAM data is included in FEC codewords, then OAM transmission is enabled, but codeword completeness is compromised
Solution Approach 1:
The patent applies local quality by designating a specific bit position within the FEC codeword structure for OAM information. Rather than disrupting the overall codeword structure or requiring additional bits, the OAM bit is embedded at a predetermined location, allowing the rest of the codeword to maintain its complete and stable composition for error correction purposes.
Solution Approach 2:
The codeword structure is pre-configured with a designated bit position for OAM information before encoding begins. This preliminary structural arrangement ensures that when OAM data needs to be transmitted, it can be seamlessly integrated into the predetermined location without requiring any structural modifications or compromising codeword completeness.
3Measurement precision
If sync-header patterns are used for synchronization, then synchronization accuracy is improved, but detection complexity increases
Solution Approach 1:
The patent employs asymmetric sync-header patterns where the OAM bit value determines which of two complementary patterns is used: (00, 11, 11, 00) for one OAM state and (11, 00, 00, 11) for the other. This asymmetric design provides clear distinction between different OAM states while maintaining simple detection logic, as the receiver only needs to identify which pattern is present to determine both synchronization and OAM information.
Data Source
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AI summary
An apparatus comprises a 64b66b encoder configured to process operations, administration, and maintenance (OAM) information, determine a bit pattern based on the OAM information, form forward error correction (FEC) parity sync-headers based on the bit pattern, and form an FEC codeword with the FEC parity sync-headers, and a transmitter coupled to the 64b66b encoder and configured to transmit the FEC codeword. A method comprises processing OAM information, determining a bit pattern based on the OAM information, forming FEC parity sync-headers based on the bit pattern, forming an FEC codeword with the FEC parity sync-headers, and transmitting the FEC codeword. An apparatus comprises a receiver configured to receive an FEC codeword, and a 64b66b decoder coupled to the receiver and configured to extract FEC parity sync-headers from the FEC codeword, determine a bit pattern of the FEC parity sync-headers, and determine OAM information based on the bit pattern.