Optical Skew Adjustment via Pilot Signal Phase Analysis
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Solution Overview
Problem
Existing optical communication systems face challenges in accurately adjusting skew between the I and Q components of optical signals, which affects signal quality and bit error rates, especially when the quality of the received optical signal is above a certain threshold, making precise skew adjustment difficult.
Innovation Solution
An optical reception apparatus that includes a converting unit, suppression processor, extraction unit, and a first ratio calculator to analyze the amplitude and phase components of pilot symbols, transmitting adjustment information to the optical transmission apparatus to optimize skew between the I and Q components, allowing for precise control of the skew adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the quality of the received optical signal is evaluated with the error rate after error correction, then the reliability of communication is improved, but when the quality is equal to or higher than a predetermined level, the error rate becomes 0% and causes difficulty in specification of the peak of the quality, worsening the measurement precision
Solution Approach 1:
The patent introduces a dedicated pilot signal as an intermediary element to measure skew. The pilot signal is inserted at a specific position in the transmission signal and has a known phase relationship with the I and Q components. By measuring the phase difference of the recovered pilot signal, the system can accurately determine skew without being affected by the 0% error rate issue that occurs when using ordinary data signals with error correction.
2Productivity
If the symbol rate is increased to increase the capacity of optical networks, then the productivity is improved, but the skew between I and Q components becomes more significant, worsening the signal quality
Solution Approach 1:
The patent implements a feedback mechanism where the receiving apparatus measures the skew using the pilot signal and sends adjustment instructions back to the transmitting apparatus. The transmitting apparatus adjusts its skew control based on this feedback to minimize the measured skew. This closed-loop control allows the system to maintain high signal quality even at increased symbol rates by dynamically compensating for skew effects.
Data Source
AI summary
An optical reception apparatus includes an equalization processor, an extraction unit, a first ratio calculator, and an instruction transmitter. The equalization processor suppresses fluctuations in amplitude of an electrical signal obtained by converting an optical signal including a plurality of pilot symbols subjected to BPSK modulation by an optical transmission apparatus. The extraction unit extracts the pilot symbols from the electrical signal with suppressed fluctuations in amplitude. The first ratio calculator calculates a ratio of an amplitude component to a phase component of each of the pilot symbols extracted by the extraction unit. The instruction transmitter transmits information relating to skew adjustment based on the ratio of the amplitude component to the phase component calculated by the first ratio calculator for each of different control values to the optical transmission apparatus.