Hybrid Scrambled Transmission Coding for Backplane Channels
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Solution Overview
Problem
Existing digital data transmission systems face inefficiencies in coding overhead, particularly with 8b/10b and 64b/66b coding schemes, leading to high channel usage and synchronization challenges, especially at high speeds.
Innovation Solution
A hybrid channel coding method using a scrambler to prepare digital data for transmission, incorporating unscrambled codewords to maintain channel timing and DC balance, and employing an x29+x19+1 scrambler to achieve efficient power spectral density matching with control sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If 8b/10b coding is used to maintain timing and DC balance, then transmission reliability is improved, but channel overhead increases to more than 20%
Solution Approach 1:
The transmission channel is segmented into control sequences and data sequences. Control sequences use traditional 8b/10b coding to maintain timing and DC balance, while data sequences use scrambled coding for higher efficiency. This segmentation allows each segment to use the most appropriate coding method for its specific requirements.
Solution Approach 2:
The invention changes the coding parameter from fixed 8b/10b coding for all data to a variable approach where control sequences use 8b/10b coding and data sequences use scrambled coding with different polynomial parameters (e.g., x29+x19+1). This parameter change optimizes both reliability and efficiency.
2Productivity
If scrambled coding is used to increase channel efficiency, then coding overhead is reduced, but synchronization difficulty increases
Solution Approach 1:
Control sequences act as intermediaries between the scrambled data sequences and the receiver synchronization mechanism. These unscrambled control sequences provide recognizable patterns that enable the receiver to maintain synchronization without requiring complex synchronization circuits.
Solution Approach 2:
The system preliminarily prevents synchronization loss by periodically inserting unscrawbled control sequences into the scrambled data stream. These control sequences anticipate and prevent potential synchronization drift before it causes errors.
3Reliability
If control sequences are inserted frequently to maintain synchronization, then synchronization reliability is improved, but channel overhead increases
Solution Approach 1:
Instead of using control sequences for every data block (excessive action), the system uses control sequences partially - only periodically or when synchronization is needed. This partial application maintains sufficient synchronization reliability while minimizing overhead and maximizing channel efficiency.
Data Source
AI summary
In one embodiment, a hybrid backplane coding scheme transmits data using lengthy sequences of scrambled data, separated by 8b/10b control character sequences that prepare the receiver for the next scrambled sequence and permit realignment if necessary. Advantageously, the sender of the scrambled data can be changed during the control character sequence. The hybrid backplane coding scheme can be designed such that the power spectral density of scrambled data and control character sequences are similar, which permits good performance with high-speed electrical differential receivers. Other embodiments are described and claimed.