Optical Signal Reception Processing for Nonlinear Degradation Monitoring
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Solution Overview
Problem
In ultra-high-speed long-distance optical transmission systems, it is challenging to monitor and specify the degradation cause of signal quality in real time due to nonlinear optical effects in optical fibers, which affect the optical signal-to-noise ratio and lead to signal degradation.
Innovation Solution
A signal reception processing apparatus and method that includes a digital signal processing unit to demodulate signals, calculate a Q value based on symbol distribution and distance, an error correction unit for forward error correction, and a control unit to calculate a penalty for signal quality degradation caused by nonlinear optical effects, using Q_const and Q_ber values to differentiate between linear and nonlinear degradations without additional measuring equipment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical transmission monitoring is used, then transmission capability is maintained, but the ability to specify nonlinear optical effect degradation in real time is insufficient
Solution Approach 1:
The patent segments the Q value calculation into two distinct components: Q_const (based on constellation diagram symbol distribution) and Q_ber (based on bit error rate after FEC). This segmentation allows separate measurement of different degradation mechanisms, enabling precise identification of nonlinear optical effects without requiring complex additional monitoring equipment.
Solution Approach 2:
The patent introduces the Q value difference (Q_const - Q_ber) as an intermediary parameter to indirectly measure nonlinear optical effect degradation. Instead of directly measuring complex nonlinear effects, the system uses the difference between two easily obtainable Q value measurements as a mediator to quantify the degradation caused by nonlinear optical effects.
2Measurement precision
If additional measuring equipment is added to monitor signal degradation, then measurement precision improves, but apparatus cost increases
Solution Approach 1:
The patent makes the existing optical receiver perform multiple functions: it simultaneously calculates Q_const from constellation diagrams, Q_ber from bit error rates, and derives nonlinear effect degradation from their difference. This multi-functionality eliminates the need for separate dedicated monitoring equipment, reducing apparatus cost while maintaining high measurement precision.
Solution Approach 2:
The system uses its own internal measurements (constellation symbol distribution and FEC error rates) to self-diagnose nonlinear optical effect degradation. Instead of requiring external monitoring equipment, the optical receiver serves itself by utilizing its existing functional components to generate the necessary measurement data for degradation analysis.
3Productivity
If transmission distance is increased to expand coverage, then transmission capacity improves, but signal degradation from nonlinear optical effects worsens
Solution Approach 1:
The patent implements a feedback mechanism where the calculated penalty value (representing nonlinear effect degradation) is used to monitor and assess signal quality in real-time. This feedback enables dynamic adjustment of transmission parameters or identification of problematic segments, allowing the system to maintain reliability even when transmission distance and capacity are increased.
Data Source
AI summary
A signal reception processing apparatus includes a digital signal processing unit that calculates a first Q value based on distribution of the symbols of the demodulated signal and distance between the symbols of the demodulated signal, and an error correction unit that outputs corrected signal as a demodulation electric signal, and calculates a second Q value based on an error rate at the time of the correction, and a control unit that calculates a penalty that indicates degradation quantity of signal quality caused by a nonlinear optical effect of an optical fiber based on the first Q value and the second Q value.