Alignment Marker Search Using FEC Granularity Against Burst Errors
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Solution Overview
Problem
Skew occurs during multi-lane parallel transmission of data streams through Ethernet interfaces, leading to inefficiencies in data alignment and increased sensitivity to burst bit errors.
Innovation Solution
An alignment marker search method that multiplexes data streams at a reference granularity corresponding to FEC codewords, allowing for efficient AM search with reduced sensitivity to burst bit errors by demultiplexing or directly obtaining data segments at specific intervals, using CM fields for faster alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data streams are multiplexed at bit granularity (1 bit) for high-speed Ethernet transmission, then transmission rate is improved, but the number of symbols affected by burst bit errors increases significantly
Solution Approach 1:
The patent segments the multiplexing process by introducing a reference granularity that is larger than 1 bit (specifically, the granularity of one or more FEC codewords). This segmentation groups multiple bits together as a unit, so that when bit multiplexing occurs, errors are contained within smaller segments rather than affecting all symbols in the data stream. The reference granularity acts as a boundary that limits the spread of burst errors.
Solution Approach 2:
The patent changes the multiplexing parameter from bit granularity (1 bit) to reference granularity (quantity of bits corresponding to n symbols of FEC codeword). This parameter change fundamentally alters how data is organized and transmitted, transforming the system from being highly sensitive to burst errors to having inherent error containment capabilities. The new parameter setting ensures that multiplexing operations respect the FEC codeword structure, thereby protecting against error propagation.
2Device complexity
If alignment marker search is performed on fully multiplexed data streams without demultiplexing, then device complexity is reduced, but measurement precision of alignment marker detection decreases
Solution Approach 1:
The patent applies preliminary action by performing demultiplexing operations before the alignment marker search process. By separating the multiplexed data streams into their original components prior to searching for alignment markers, the system ensures that markers are detected in their native, uncorrupted context. This preliminary separation improves detection accuracy while the subsequent re-multiplexing or selective processing maintains reasonable device complexity.
Solution Approach 2:
The patent introduces an intermediary demultiplexing stage that acts as a mediator between the multiplexed data stream and the alignment marker search process. This intermediary component temporarily separates the data streams, allowing accurate marker detection, and then can recombine or selectively process the data. This intermediary approach balances the trade-off by adding controlled complexity only where needed for accurate measurement.
Data Source
AI summary
In an alignment marker search method, a first module receives a first data stream, where the first data stream is obtained by multiplexing a plurality of second data streams at a reference granularity, any second data stream includes an AM and data from at least one FEC codeword, and the reference granularity is a quantity of bits corresponding to n symbols included in the FEC codeword; obtains a first data segment from a first location in the first data stream at the reference granularity; and performs AM search on the first data segment. The reference granularity is the quantity of bits corresponding to the n symbols. Therefore, when a burst bit error occurs in the first data stream, a quantity of symbols affected by the burst bit error is small.