Running Disparity Encoding for DC-Free High-Efficiency Links
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing encoding schemes such as 8b/10b, 64b/66b, and 64b/67b may compromise transmission efficiency, fail to achieve DC-free encoding, or deteriorate run length, leading to challenges in accurate decoding and clock reproduction.
Innovation Solution
An encoding device and method that divide input data into N or M bits, calculate a running disparity, and determine whether to invert the data string based on the disparity and a previous disparity, adding a flag to indicate the result, while excluding control codes from inversion and flag addition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 8b/10b encoding scheme is used, then DC-free encoding is achieved, but transmission efficiency is lowered
Solution Approach 1:
The patent changes the encoding parameters by using 64b/66b encoding instead of 8b/10b, and introduces a running disparity control mechanism with inversion flags to achieve DC-free encoding at higher efficiency. The encoding ratio is changed from 8b/10b (20% overhead) to 64b/66b (3.125% overhead), significantly improving transmission efficiency while maintaining DC-free property through active running disparity management.
2Productivity
If 64b/66b encoding scheme is used, then transmission efficiency is improved, but DC-free encoding is not achieved
Solution Approach 1:
The patent implements a feedback mechanism by calculating running disparity based on previous disparity values and using inversion flags to control the encoding output. The encoder monitors the running disparity and selectively inverts data strings to maintain DC-free encoding, creating a closed-loop control system that ensures both high transmission efficiency and DC-free property.
Solution Approach 2:
The patent performs preliminary calculation of running disparity before encoding, and pre-determines whether inversion is needed based on the calculated disparity value. This preliminary action allows the encoder to proactively maintain DC-free encoding rather than reactively correcting violations, ensuring continuous DC balance throughout the transmission.
3Reliability
If 64b/67b encoding scheme is used, then DC-free encoding is achieved, but run length is deteriorated
Solution Approach 1:
The patent changes the encoding scheme from 64b/67b to 64b/66b, reducing the overhead from 3.125% to 1.5625%. This parameter change improves run length characteristics while maintaining DC-free encoding through the running disparity control mechanism, achieving both goals simultaneously rather than trading one for the other.
4Reliability
If data string inversion is performed to control running disparity, then DC-free encoding is achieved, but control codes may be affected
Solution Approach 1:
The patent introduces an intermediary mechanism (inversion flag) that mediates between the need for running disparity control and the requirement to preserve control code integrity. The flag system allows the encoder to indicate inversion without actually altering control codes, and the decoder can correctly interpret the original data by applying the indicated inversion, thus protecting control code information while maintaining DC-free encoding.
Data Source
AI summary
The technology relates to an encoding device, an encoding method, a decoding device, a decoding method, and a program enabling encoding with favorable transmission efficiency with a controlled running disparity.A calculation section divides inputted data into N or M bits to calculate a first running disparity of an N or M bit data string. A determination section determines whether the data string is inverted based on the first running disparity calculated by the calculation section and a second running disparity calculated therebefore. An addition section inverts or non-inverts the data string based on a determination result by the determination section to add a flag indicating the determination result for outputting. The determination section determines not to perform inversion when the data string is a control code. The addition section adds the flag assigned to the control code. The technology is applicable to a device communicating in an SLVS-EC specification.