Phase Noise Compensation Using Transmitter Imperfection Estimation
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Solution Overview
Problem
Complex QAM modulation formats in coherent optical communication systems are sensitive to phase noises caused by laser imperfections and transmitter device imperfections, leading to severe code errors and limited transmission efficiency, as existing phase noise compensation methods do not account for transmitter imperfections.
Innovation Solution
A phase noise compensation apparatus and method that determines estimated values of transmitter imperfection parameters and uses training sequence signals to modify transmission signals, allowing for accurate phase noise estimation and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing phase noise compensation methods (blind phase search or carrier phase estimation based on QPSK) are used, then phase noise compensation is performed, but transmitter imperfections (direct current bias, amplitude imbalance, phase imbalance) are not accounted for, resulting in severe code errors and limited transmission efficiency
Solution Approach 1:
The patent applies preliminary action by first estimating transmitter imperfection parameters (direct current bias, amplitude imbalance, phase imbalance) before performing phase noise compensation. The received signal is processed to obtain initial estimates of these imperfection parameters, which are then used to modify the received signal before phase noise estimation and compensation. This preliminary correction of transmitter imperfections enables accurate phase noise compensation and avoids severe code errors.
2Productivity
If complex QAM modulation format is used to increase transmission rates, then spectral efficiency is improved, but sensitivity to phase noises (both laser and transmitter imperfections) increases, resulting in severe code errors
Solution Approach 1:
The patent applies preliminary action by first estimating and compensating for transmitter imperfections (direct current bias, amplitude imbalance, phase imbalance) before phase noise compensation. This preliminary correction removes the harmful effects of transmitter imperfections that would otherwise cause severe code errors in complex QAM systems, enabling reliable high-rate transmission.
Solution Approach 2:
The patent uses feedback by iteratively refining the estimates of transmitter imperfection parameters and phase noise parameters. The initial estimates obtained from the received signal are used to modify the signal, and the process is repeated to improve accuracy. This feedback mechanism ensures that both transmitter imperfections and phase noises are accurately compensated, maintaining low code error rates at high transmission rates.
3Device complexity
If phase noise compensation is performed without accounting for transmitter imperfections, then compensation process is simple, but phase noise estimation accuracy is reduced, limiting transmission efficiency
Solution Approach 1:
The patent applies segmentation by dividing the compensation process into distinct stages: first estimating transmitter imperfection parameters (direct current bias, amplitude imbalance, phase imbalance), then using these estimates to modify the received signal, and finally performing phase noise estimation and compensation on the modified signal. This segmentation allows each stage to focus on specific imperfections, improving overall accuracy while maintaining manageable complexity through systematic processing.
Data Source
AI summary
Embodiments of this disclosure provide a phase noise compensation apparatus and method and a receiver, in which modified signals are determined according to estimated values of an imperfection parameter of a transmitter and training sequence signals in transmission signals, and phase noises of the received signals are determined according to the modified signals, hence, an effect of the imperfection parameter of the transmitter on the phase noise is taken into account, and the phase noise may be accurately estimated, thereby performing compensation on the phase noise, and ensuring a transmission efficiency and performance of the system.