Multistage Probabilistic Signal Shaping Encoder
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Solution Overview
Problem
Probabilistic signal shaping in nonlinear optical channels faces energy efficiency penalties due to short block lengths, which also impact performance in linear channels, and existing solutions struggle to balance circuit complexity and energy efficiency while maintaining high shaping gain.
Innovation Solution
A multistage shaping encoder is employed, with a first stage using a short block length shaping code for nonlinear channels and a second stage using a longer block length code to reduce penalties and improve performance in both linear and nonlinear channels, while maintaining low circuit implementation complexity and high energy efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a short block length shaping code is used, then the performance in nonlinear optical channels is improved, but the energy efficiency deteriorates
Solution Approach 1:
The patent divides the shaping encoding process into two independent stages: a first stage using a short block length shaping code optimized for nonlinear optical channels, and a second stage using a long block length shaping code optimized for energy efficiency. This segmentation allows each stage to be optimized for its specific function without compromising the other, resolving the contradiction between nonlinear channel performance and energy efficiency.
2Use of energy by moving object
If a long block length shaping code is used, then the energy efficiency is improved, but the performance in nonlinear optical channels deteriorates
Solution Approach 1:
The patent segments the shaping function into two stages with different block lengths. The first stage uses a short block length code that maintains good performance in nonlinear optical channels, while the second stage uses a long block length code that achieves high energy efficiency. The cascade connection of these two stages allows the system to simultaneously achieve both goals.
3Reliability
If probabilistic signal shaping is implemented, then the shaping gain is improved, but the circuit complexity increases
Solution Approach 1:
The patent divides the shaping encoder into two stages, where each stage can be independently designed and optimized. This segmentation allows the use of simpler coding schemes in each stage rather than requiring a single complex long-block code, thereby reducing overall circuit implementation complexity while maintaining high shaping gain.
Data Source
AI summary
A shaping encoder capable of improving the performance of PCS in nonlinear optical channels by performing the shaping in two or more stages. In an example embodiment, a first stage employs a shaping code of a relatively short block length, which is typically beneficial for nonlinear optical channels but may cause a significant penalty in the energy efficiency. A second stage then employs a shaping code of a much larger block length, which significantly reduces or erases the penalty associated with the short block length of the first stage while providing an additional benefit of good performance in substantially linear optical channels. In at least some embodiments, the shaping encoder may have relatively low circuit-implementation complexity and/or relatively low cost and provide relatively high energy efficiency and relatively high shaping gain for a variety of optical channels, including but not limited to the legacy dispersion-managed fiber-optic links.