Optical Communication Device Polarization Estimation
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Solution Overview
Problem
Existing optical communication systems face challenges in rapidly estimating and demultiplexing polarization states of multiplexed signals due to the slow convergence of adaptive equalization filters and the lengthening of the header portion when adding a signal composed of only multiplexed polarizations in a time-division manner.
Innovation Solution
An optical communication device that transmits polarization multiplexed signals with pilot sequences of distinct frequencies at the beginning of each burst signal, allowing for simultaneous estimation of polarization states using maximal ratio combining and adaptive equalization, thereby speeding up demultiplexing without lengthening the header.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a header signal composed only of each multiplexed polarization is added in a time-division manner to speed up convergence, then polarization state estimation is accelerated, but the header portion becomes longer
Solution Approach 1:
The patent combines both polarization states into a single pilot sequence by assigning different frequency components to different polarizations. The pilot sequence contains frequency components where one frequency corresponds to one polarization and another frequency corresponds to the orthogonal polarization, allowing simultaneous estimation of both polarization states without requiring separate time-division header signals.
Solution Approach 2:
The patent transitions from time-division multiplexing of polarization headers to frequency-division multiplexing. Instead of adding header signals at different time intervals, the invention embeds polarization information in the frequency domain, where different polarizations are distinguished by their frequency components within the same time window.
2Ease of operation
If sequential update algorithm is used to update adaptive equalization filter coefficients, then polarization demultiplexing can be performed, but convergence time is excessive
Solution Approach 1:
The patent performs preliminary polarization state estimation using the pilot sequence before the main data transmission begins. By extracting polarization information from the known pilot sequence with distinct frequency components, the system prepares the adaptive equalization filter coefficients in advance, avoiding the need for slow sequential convergence during actual data demultiplexing.
Solution Approach 2:
The patent replaces the iterative sequential update mechanism with a direct estimation approach. Instead of repeatedly updating filter coefficients through sequential algorithms, the system uses frequency-based polarization estimation to directly determine the polarization states, substituting the mechanical iterative process with a more efficient frequency-domain analysis.
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 enables rapid estimation and demultiplexing of polarization states, reducing the time required for polarization demultiplexing and maintaining a shorter header portion, thus enhancing the efficiency of polarization multiplexed signal processing.
Implementation Method 1
a coherent light reception unit adapted to output a coherent detection signal by performing conversion into an electrical signal by allowing the optical signal transmitted from the transmitter and local light to interfere with each other
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
A transmitter (100) generates a burst signal obtained by multiplexing signals of a first polarization and a second polarization orthogonal to each other, and including, at the beginning thereof, a pilot sequence in which the first and the second polarizations each have single frequency components of a first frequency and a second frequency different from each other. A coherent light reception unit (201) performs conversion into an electrical signal by allowing received light and local light to interfere with each other. A pilot sequence detection unit (203) detects a pilot sequence from the converted electrical signal. The polarization estimation unit (204) estimates polarization states of the first polarization and the second polarization at a receiver (200) from frequency components corresponding to the first frequency, and the second frequency. An equalizer (205) demultiplexes the first polarization and the second polarization on the basis of the estimated polarization states.