Optical Signal SNR Estimation Using Pseudo-Random Sequences
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Solution Overview
Problem
Conventional optical communication systems face degradation in transmission quality when measuring signal-to-noise ratio (SNR) due to the halving of transmissible information and efficiency issues caused by biased frequency components from inserted pattern signals, leading to nonlinear optical effects.
Innovation Solution
A method involving the insertion of pseudo-random signal sequences into transmission data, extraction of these sequences from received signals, calculation of inner product values, and determination of SNR based on reception power, which prevents bias towards specific frequency components and maintains transmission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a predetermined pattern signal with periodicity is inserted into the main signal to measure SNR, then the transmission efficiency is improved, but the transmission quality is degraded due to nonlinear optical effects caused by frequency component bias
Solution Approach 1:
The patent changes the signal sequence from periodic patterns (010101...) to pseudo-random sequences. This parameter change in signal structure eliminates frequency component bias while maintaining the ability to measure SNR, thus resolving the contradiction between transmission efficiency and quality
Solution Approach 2:
The patent uses pseudo-random signal sequences that can be easily generated and discarded after measurement, replacing complex periodic patterns. These sequences serve their measurement purpose and are then replaced, maintaining system simplicity while avoiding nonlinear optical effects
2Device complexity
If one polarized wave is used as SNR monitor in polarization-nulling scheme, then the measurement can be performed without additional devices, but the transmissible information amount is halved
Solution Approach 1:
The patent makes the signal sequence insertion method applicable to both polarization modes simultaneously. By inserting pseudo-random sequences into both polarized waves, the system can measure SNR for both channels without requiring separate measurement devices, thus eliminating information loss while maintaining device simplicity
Solution Approach 2:
The patent segments the measurement process by inserting independent pseudo-random sequences into each polarized wave. This allows parallel measurement of both polarization channels, preventing the halving of transmissible information that occurs when only one polarized wave is monitored
Data Source
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AI summary
A signal-to-noise ratio (SNR) estimation method includes an optical signal transmission step of inserting at least one pair of signal sequences into transmission data and transmitting the transmission data into which the at least one pair of signal sequences is inserted, a signal sequence extraction step of extracting the at least one pair of signal sequences from a received signal obtained by receiving the transmitted transmission data, an inner product calculation step of calculating an inner product value of the extracted at least one pair of signal sequences, a reception power calculation step of calculating reception power of the extracted at least one pair of signal sequences, and an SNR calculation step of calculating an SNR of the at least one pair of signal sequences on the basis of the calculated inner product value and the calculated reception power.