Nonlinear Signal Estimation Using Time-Varying Pulse Interactions
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Solution Overview
Problem
Existing methods for mitigating nonlinearity in optical communication systems, such as those using the split-step Fourier method or perturbation models, are complex and do not accurately account for interactions between current and previous/succeeding symbols, limiting the accuracy of signal estimation.
Innovation Solution
A nonlinear estimating apparatus and method that calculates weighted sums of interaction items between pulses at multiple moments to obtain additive and multiplicative perturbation quantities, allowing for improved signal estimation by considering time-varying effects at the receiving side.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If static perturbation quantities are used in nonlinear estimation, then calculation complexity is reduced, but signal estimation accuracy deteriorates
Solution Approach 1:
The patent transforms the static perturbation quantity into a time-varying perturbation quantity that changes with each symbol period. The perturbation quantity is dynamically updated based on the current and previous symbols, allowing the estimation to adapt to the actual signal characteristics and improve accuracy without requiring complex numerical simulations.
Solution Approach 2:
The patent pre-calculates the perturbation quantity based on known symbol information before the actual signal estimation. By using the symbol sequence (which is known at the receiver) to compute the perturbation effect in advance, the system avoids complex real-time nonlinear calculations while maintaining high estimation accuracy.
2Productivity
If interactions with previous and subsequent symbols are not considered, then computation is simplified, but estimation accuracy deteriorates
Solution Approach 1:
The patent segments the nonlinear interaction into discrete symbol periods and identifies the specific moments (current symbol and previous symbols) that contribute to the perturbation. This segmentation allows the system to consider only the relevant interactions rather than all possible symbol interactions, simplifying computation while maintaining accuracy.
Solution Approach 2:
The patent applies different treatment to different symbol moments: the current symbol and previous symbols are included in the perturbation calculation, while more distant symbols are excluded. This local quality approach focuses computational resources on the most significant interactions, improving accuracy without excessive complexity.
3Measurement precision
If numerical simulation methods like split-step Fourier method are used, then solution accuracy is improved, but computational complexity and time increase significantly
Solution Approach 1:
The patent replaces the expensive, time-consuming numerical simulation with a simple analytical calculation based on perturbation theory. The analytical solution provides sufficient accuracy for practical purposes while being computationally inexpensive and suitable for real-time implementation at the receiver.
Solution Approach 2:
The patent changes the approach from numerical simulation with fine step sizes to an analytical perturbation method that directly computes the nonlinear effect using known system parameters (dispersion, nonlinear coefficient, symbol sequence). This parameter-based approach eliminates the need for iterative numerical computation while maintaining accuracy.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The proposed solution enhances the accuracy of signal estimation by incorporating time-varying perturbation quantities, applicable to both single and polarization multiplexing systems, and compatible with various modulation formats, improving the estimation of nonlinear signals in optical communication systems.
Implementation Method 1
The nonlinearity in an optical fiber is originated from the Kerr effect, that is, the phase of transmitted light will be changed along with the variation of the power
Data Source
AI summary
The present invention provides a nonlinear estimating apparatus and method, and a receiver. The nonlinear estimating apparatus includes: an information sequence acquiring unit, configured to acquire a symbol information sequence of the pulse signal inputted by a transmitting side; a perturbation quantity generating unit, configured to calculate the weighted sum of the interaction items of the pulses on one or more moments relative to the current moment, so as to obtain an additive perturbation quantity and a multiplicative perturbation quantity produced on a transmission link with a certain length; and a signal estimating unit, configured to estimating the signal received at a receiving side according to the symbol information sequence, the additive perturbation quantity and the multiplicative perturbation quantity. With the embodiments of the present invention, the accuracy of estimation of nonlinear signals may be further improved.