Distribution Shaping Encoding for Uneven Bit Sources
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Solution Overview
Problem
In optical fiber transmission, the forced evening out of '0' and '1' appearance frequencies by bit scrambling in uneven information sources leads to an unrequired increase in entropy, which is not suitable for real-time traffic with changing statistical properties.
Innovation Solution
A distribution shaping method that allocates a symbol sequence with lower average power to a bit sequence with more '1's and a bit sequence with more '0's, using conversion tables to minimize entropy and power consumption, while maintaining a minimum distance between symbols.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If bit scrambling is used to even out appearance frequencies of '0' and '1' in optical fiber transmission, then performance deterioration due to uneven numbers is avoided, but unrequired entropy increase occurs in uneven information sources
Solution Approach 1:
The patent changes the parameter of symbol allocation by introducing a mark ratio parameter that reflects the actual distribution of '0' and '1' bits. Instead of using fixed bit scrambling, the system dynamically adjusts symbol sequence allocation based on the mark ratio of input bit sequences, thereby adapting to uneven information sources and avoiding unrequired entropy increase while maintaining transmission reliability.
2Stability of the object's composition
If forced evening out of appearance frequencies is applied to uneven information sources, then clock reproduction is maintained, but power consumption increases
Solution Approach 1:
The patent introduces dynamic adaptation by making the symbol allocation strategy dependent on the mark ratio of the input bit sequence. The system dynamically selects different allocation patterns based on whether the bit sequence has a mark ratio closer to 0 or 1, allowing it to maintain clock reproduction stability while adapting to varying information source characteristics and reducing unnecessary power consumption.
3Device complexity
If conventional symbol allocation is used for uneven information sources, then transmission is simplified, but communication efficiency decreases
Solution Approach 1:
The patent improves communication efficiency by changing the allocation parameter from fixed to variable based on mark ratio. The system uses different allocation tables or patterns depending on the mark ratio condition, which optimizes the matching between source distribution and channel characteristics, thereby improving productivity without significantly increasing device complexity.
Data Source
AI summary
In a distribution shaping method, information compression and distribution shaping are executed at the same time. A symbol sequence of a predetermined length is allocated to an input bit sequence of a predetermined length on a one-to-one basis. In the allocation, a bit sequence smaller in entropy is allocated a symbol sequence smaller in average power.