Idle Sequence Code Word Substitution for Frame Synchronization
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Solution Overview
Problem
In communication systems, determining the starting point of a frame is challenging when the length of the idle sequence is unknown, and the idle sequence does not inherently indicate its end, leading to synchronization issues for receiving nodes.
Innovation Solution
An idle sequence modifier replaces certain code words of a basic idle sequence with alternative code words, allowing receiving nodes to determine the starting point of a frame by identifying differences between the modified and basic sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the idle sequence is transmitted during gaps between packets to maintain synchronization, then the receiving node can maintain clock synchronization and frame alignment, but the receiving node cannot determine the starting point of the following packet when the idle sequence length is unknown
Solution Approach 1:
The patent extracts the synchronization indication function from the idle sequence itself by replacing certain code words with alternative code words that have distinct properties. This allows the receiving node to identify the end of the idle sequence by detecting these unique alternative code words, thereby determining the frame starting point without ambiguity.
Solution Approach 2:
The patent uses code word substitution where alternative code words act as distinct markers within the idle sequence. These alternative code words have different characteristics (such as different disparity values or patterns) that make them visually distinguishable from the basic idle sequence code words, enabling the receiving node to detect frame boundaries through pattern recognition.
2Stability of the object's composition
If the idle sequence is configured to comply with line-code characteristics (running disparity and transition density), then the line-code related characteristics are maintained, but the idle sequence cannot inherently indicate its end
Solution Approach 1:
The patent segments the idle sequence into basic code words and alternative code words with distinct functions. The basic code words maintain line-code characteristics for synchronization, while the alternative code words serve as end indicators. This segmentation allows the idle sequence to simultaneously maintain line-code compliance and provide frame boundary information.
Solution Approach 2:
The alternative code words act as intermediary elements within the idle sequence that bridge the gap between maintaining line-code characteristics and indicating frame boundaries. These intermediary code words preserve the overall line-code compliance while introducing detectable markers for frame synchronization.
3Measurement precision
If alternative code words are used to mark the end of the idle sequence, then the frame starting point can be determined accurately, but the complexity of the encoding and decoding process increases
Solution Approach 1:
The patent changes specific parameters of certain code words (such as disparity values or transition patterns) to create alternative code words that are easily distinguishable. These parameter changes are localized and minimal, allowing the encoder and decoder to identify frame boundaries through simple parameter comparison without requiring complex processing logic.
Data Source
AI summary
Methods and systems for indicating an end of an idle sequence, including: encoding a first frame, encoding a basic idle sequence including code words, producing an idle sequence by replacing certain M code words of the idle sequence with M alternative code words, and encoding a second frame. Each one of the M alternative code words appears in the basic idle sequence. And a second communication node, which is unable to determine a starting point of the second frame based only on a received idle sequence, is able to determine a start of the second frame based on a difference between the received idle sequence and the basic idle sequence.