Variable Subcarrier Power for Crosstalk Reduction
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Solution Overview
Problem
Optical super-channels in high-speed data transmission networks experience varying Bit Error Rates (BER) and Optical Signal-to-Noise Ratios (OSNR) among subcarriers due to linear and non-linear interactions, leading to uneven performance and potential crosstalk, which is undesirable for network operators.
Innovation Solution
The method involves adjusting the power levels of subcarrier bands within a super-channel, specifically attenuating intermediate subcarriers while maintaining or slightly reducing the power of edge subcarriers, to optimize interactions and equalize OSNR across all subcarriers, thereby reducing non-linear crosstalk and OSNR degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If subcarriers are tightly packed to achieve high spectral efficiency, then spectral efficiency is improved, but linear and non-linear interactions cause varying BER and OSNR among subcarriers
Solution Approach 1:
The patent applies different power levels to different subcarrier bands based on their position within the super-channel. Intermediate subcarriers are attenuated more than edge subcarriers, creating a non-uniform power distribution that compensates for the varying degrees of non-linear interactions experienced by subcarriers at different positions, thereby equalizing OSNR across all subcarriers
2Object-affected harmful factors
If Nyquist filtering is applied to minimize linear crosstalk, then linear crosstalk is reduced, but non-linear interactions still cause OSNR degradation
Solution Approach 1:
The patent changes the power parameter of subcarrier bands, specifically applying variable attenuation to intermediate subcarriers. This parameter modification directly addresses non-linear interactions by reducing the power of subcarriers that experience stronger non-linear effects, thereby equalizing OSNR and reducing non-linear crosstalk without requiring changes to the filtering approach
3Reliability
If intermediate subcarriers are attenuated to reduce non-linear interactions, then OSNR uniformity is improved, but total transmission power is reduced
Solution Approach 1:
The patent optimizes the attenuation parameters for intermediate subcarriers to achieve the minimum necessary reduction in power that equalizes OSNR across all subcarriers. By carefully controlling the degree of attenuation rather than applying uniform reduction, the system achieves OSNR uniformity while minimizing the impact on total transmission power
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
This approach results in improved OSNR uniformity and reduced crosstalk among subcarriers, enhancing overall network performance and spectral efficiency by minimizing non-linear impairments and maintaining high data transmission rates.
Implementation Method 1
optically modulating the data streams into the subcarrier bands using the assigned optical frequencies and the adjusted power levels
Data Source
AI summary
A method and system for reducing crosstalk among subcarriers of a super-channel may involve adjusting power levels of the subcarriers. In one example, power levels of edge and/or intermediate subcarriers may be reduced relative to center subcarriers in the super-channel band. The adjustment in power level may lead to overall reduction in optical signal-to-noise ratio degradation.