Coherent Optical EEPN Modeling via Frequency-Domain Impulse Response
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Solution Overview
Problem
High-speed coherent communication systems face challenges from channel impairments like dispersion and polarization mode dispersion, which cause inter-symbol interference, and phase noise amplified by equalization, limiting transmission rate and distance.
Innovation Solution
A method and apparatus for determining characteristics of equalization-enhanced phase noise (EEPN) by acquiring operation parameters, calculating an accumulated dispersion coefficient, and deriving a frequency-domain impulse response to model and compensate for EEPN.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If equalization technologies are used to compensate for channel impairments, then inter-symbol interference is eliminated, but phase noise is amplified resulting in equalization-enhanced phase noise
Solution Approach 1:
The patent segments the phase noise compensation process into two distinct parts: (1) standard phase noise compensation using traditional algorithms, and (2) EEPN compensation using the newly derived frequency-domain impulse response. This segmentation allows each compensation mechanism to address its specific noise component independently, preventing the equalization process from amplifying phase noise while still eliminating inter-symbol interference.
Solution Approach 2:
The patent introduces a frequency-domain impulse response as an intermediary element that characterizes the EEPN effect. This impulse response serves as a transfer function that mediates between the equalization process and the phase noise, allowing the system to model and compensate for EEPN without disrupting the beneficial equalization of channel impairments.
2Productivity
If higher-order modulation schemes are used to increase spectral efficiency, then transmission rate is improved, but system becomes more sensitive to phase noise and bit error rate increases
Solution Approach 1:
The patent changes the parameter representation of phase noise from time-domain fluctuations to frequency-domain impulse response characteristics. By deriving and utilizing the frequency-domain impulse response H_EEPN(f), the system can more effectively track and compensate for phase noise variations, thereby maintaining lower bit error rates even when using higher-order modulation schemes that are inherently more sensitive to phase noise.
3Length of stationary object
If transmission distance is increased to expand network coverage, then channel impairments accumulate, but equalization-enhanced phase noise also accumulates limiting maximum transmission distance
Solution Approach 1:
The patent performs preliminary characterization of the EEPN effect by deriving the frequency-domain impulse response based on system parameters such as dispersion coefficient, fiber length, and local oscillator properties. This preliminary modeling allows the system to predict and compensate for accumulated EEPN before transmission, enabling extended transmission distances without being limited by accumulated phase noise effects.
Data Source
AI summary
The present disclosure generally relates to high-speed coherent communication, more particularly, relates to method and apparatus for determining characteristics of equalization enhanced phase noise (EEPN) in coherent optical communication systems. According to one aspect of the present disclosure, there is provided a method for determining characteristics of EEPN in a coherent optical communication system. The method comprise: acquiring operation parameters associated with EEPN of the coherent optical communication system are acquired; determining an accumulated dispersion coefficient for the coherent optical communication system based on the operation parameters; and determining a frequency-domain impulse response based on the accumulated dispersion coefficient and a frequency-domain signal related to a local oscillator of the coherent optical communication system.