Phase Jump Correction in Coherent Optical Transmission
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Solution Overview
Problem
In coherent optical transmission systems, phase jumps during carrier phase estimation lead to significant performance degradation and errors in QPSK signal demodulation, as existing methods struggle to accurately detect and correct phase jumps due to high data rates and complex carrier phase estimation processes.
Innovation Solution
A phase jump correction method that involves generating and using training sequences to determine and modify phase values, allowing for effective phase jump detection and correction without complicating the carrier phase estimation module, thereby simplifying the system and reducing errors in FEC decoding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If nonlinear carrier phase estimation algorithms (biquadratic or costas) are used for QPSK demodulation, then carrier phase recovery is achieved, but phase jump errors (0°, 90°, 180°, 270°) occur due to phase deviation and nonlinearity
Solution Approach 1:
The patent applies preliminary action by detecting phase jumps using training sequences before they propagate errors through the demodulation process. The receiver detects phase jumps in training sequences extracted from received signals, determines correction values, and compensates subsequent data symbols, preventing error propagation throughout the data block.
Solution Approach 2:
The patent uses training sequences as an intermediary element to detect and correct phase jumps. These known sequences serve as reference signals that mediate between the distorted received signal and the original transmitted data, enabling accurate phase jump detection and correction without directly processing the ambiguous data symbols.
2Reliability
If phase jump correction is implemented using existing methods, then phase correction capability is provided, but system complexity increases and implementation becomes cumbersome
Solution Approach 1:
The patent extracts phase jump detection and correction functionality as a separate, dedicated module independent from the carrier phase estimation module. This extraction allows the phase jump correction to be implemented as a standalone process that operates on training sequences, simplifying the overall system architecture and reducing implementation complexity.
Solution Approach 2:
The patent uses copies of training sequences (both received and locally generated) to perform phase jump detection. By comparing the received training sequence copy with the locally generated copy, the system can detect phase jumps without requiring complex processing of the actual data symbols.
3Productivity
If high data rates are used in coherent optical transmission, then transmission capacity increases, but phase jump detection and correction becomes more difficult due to reduced processing time
Solution Approach 1:
The patent performs phase jump detection preliminarily during the training sequence processing stage, before main data demodulation. This preliminary detection allows the system to identify and correct phase jumps using the known training sequence structure, reducing the processing burden during high-speed data reception.
Solution Approach 2:
The patent replaces complex mechanical processing with mathematical operations on complex symbols. Phase jump detection is achieved through mathematical comparison of received and generated training sequences, and correction is performed through complex multiplication, enabling high-speed processing suitable for high data rate transmissions.
Data Source
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AI summary
A phase jump correction method and device are provided. The method includes: acquiring, by a receiving end, a sending end Training Sequences (TSs) generated by a sending end, and generating receiving end TSs by using a TS generation mode identical to a TS generation mode used at the sending end; determining a phase value of target TSs according to the acquired sending end TSs and the generated receiving end TSs; modifying, according to phase values of a plurality of non-target TSs of the receiving end, the phase value of the target TSs to obtain a modified phase value; and performing, according to the obtained modified phase value, phase jump correction on service data received from the sending end.