8B/10B Encoder Look-Ahead Table for Running Disparity Balancing
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Solution Overview
Problem
Conventional 8b/10b encoding schemes are limited by the need to wait for previous data units to be encoded to determine disparity, significantly reducing encoding speed due to dependency on previous encoding results, especially in cases where encoding of later units must wait for earlier units to complete.
Innovation Solution
The use of a look-ahead table to determine the balancing capability of encoded data units allows for simultaneous encoding of data units, enabling encoding to start before previous units are finished and balancing running disparity by predicting the disparity from the look-ahead table.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional 8b/10b encoding schemes are used where encoding of each data unit depends on previous encoding results to balance disparity, then disparity balancing is achieved, but encoding speed is significantly reduced due to sequential processing requirements
Solution Approach 1:
The patent pre-calculates and stores the balancing capability of each possible 8-bit data unit in a look-ahead table before encoding occurs. This preliminary action allows the encoder to know in advance how each data unit will affect running disparity, enabling parallel encoding of multiple data units without waiting for previous encodings to complete, thus resolving the contradiction between maintaining disparity balancing and achieving high encoding speed
Solution Approach 2:
The look-ahead table is constructed in advance with pre-computed disparity information for all possible input data units. This pre-computation eliminates the need for sequential dependency during actual encoding operations, as each encoder can independently query the pre-computed table to determine appropriate encoding decisions, thereby maintaining reliability while improving productivity
2Manufacturing precision
If encoding of later data units waits for completion of earlier data units to determine running disparity, then accurate disparity control is maintained, but encoding time is significantly increased
Solution Approach 1:
The look-ahead table pre-stores the balancing capability information for all possible 8-bit data units, allowing encoders to determine disparity control decisions without waiting for previous encoding operations to complete. This pre-computation maintains accurate disparity control while eliminating sequential waiting time
Solution Approach 2:
The patent divides the encoding process into independent parallel segments where multiple data units can be encoded simultaneously. Each encoder segment can independently query the look-ahead table and perform encoding operations in parallel, maintaining precision through pre-computed information while reducing total encoding time through parallel processing
3Productivity
If multiple encoders operate in parallel without look-ahead tables, then encoding speed increases, but disparity balancing capability is lost due to lack of running disparity information
Solution Approach 1:
The look-ahead table serves as an intermediary information structure that provides pre-computed disparity balancing information to multiple parallel encoders. Each encoder can independently query this intermediary table to make informed encoding decisions that maintain overall disparity balancing, enabling parallel operation without sacrificing reliability
Solution Approach 2:
The look-ahead table pre-computes and stores balancing capability information that acts as a guide for parallel encoders. This preliminary preparation of disparity information allows multiple encoders to operate independently in parallel while still maintaining coordinated disparity balancing across all encoded data units
Data Source
AI summary
A method for encoding data packets includes providing an encoding scheme for coding source data units into encoded data units; establishing a first look-ahead table for the source data units; providing a data packet including a first source data unit and a second source data unit; encoding the first source data unit to generate a first encoded data unit; indexing the first look-ahead table using the first source data unit to determine a balancing capability of the first encoded data unit for balancing a running disparity; and encoding the second source data unit to generate a second encoded data unit using the balancing capability of the first encoded data unit.