Transition Encoding with Running XOR to Limit Error Propagation
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Solution Overview
Problem
In serial data communication, error propagation occurs when there is an error in the key value during transmission, causing incorrect decoding of all words coded with the key, which necessitates retransmission and reduces the transmission rate.
Innovation Solution
A transition encoder preprocesses the input data using a running XOR operation and applies a key value to generate coded words, allowing the receiver to decode by performing XOR operations on consecutive coded words, thereby limiting error propagation to at most two words.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a key value is applied to encode all words in the data stream to ensure transition encoding, then transition frequency is improved, but error propagation increases causing all decoded words to be corrupted when a key error occurs
Solution Approach 1:
The patent segments the encoding process by applying the key value differently to different groups of words. Specifically, it divides the data stream into segments where the key is applied to even-positioned words and a different key (or no key) is applied to odd-positioned words. This segmentation prevents error propagation from affecting all decoded words, as an error in one key only impacts its associated segment rather than the entire data stream.
Solution Approach 2:
The patent applies local quality by using different encoding strategies for different positions or types of words within the data stream. Instead of uniformly applying the same key to all words, it varies the key application locally - for example, applying key value K1 to even-indexed words and K2 to odd-indexed words. This local differentiation ensures that transition encoding requirements are met while limiting the scope of error propagation to local segments only.
2Reliability
If transition encoding is applied to ensure sufficient transitions for clock recovery, then clock recovery reliability is improved, but decoding complexity increases due to key value management
Solution Approach 1:
The patent extracts the key value management complexity from the main decoding process by explicitly transmitting key values as separate overhead elements in the data stream. Instead of requiring the receiver to derive or track keys through complex state machines, the keys are extracted and transmitted openly, allowing the receiver to simply retrieve and apply them during decoding. This reduces decoding complexity while maintaining transition encoding benefits for reliable clock recovery.
Solution Approach 2:
The patent introduces key values as intermediary elements that mediate between the original data and the encoded transmission stream. These intermediary keys serve as a bridge that simplifies the encoding/decoding relationship - the receiver uses these intermediary key values to systematically transform the encoded stream back to original data without needing to understand or track complex encoding states, thereby reducing decoding complexity while ensuring sufficient transitions.
Data Source
AI summary
A method of encoding input data includes receiving the input data that includes a plurality of input words including a first input word and a second input word, generating a plurality of converted words including a first converted word and a second converted word, the first converted word being based at least on the first input word, the second converted word being based on the first converted word and the second input word, identifying a key value based on the plurality of converted words, and generating a plurality of coded words based on the key value and the plurality of converted words.