Optical Transmission Device Phase Shifting for Multilevel Signal Integrity
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Solution Overview
Problem
In optical transmission systems, the fixed pattern of OTN maintenance signals after scrambling leads to performance degradation when mapped to multilevel signals like polarization multiplexed 16QAM, especially in high-speed long-haul communications.
Innovation Solution
An optical transmission device with transmission frame processors that shift the phase of patterns between transmission frames, using digital modulators and demodulators to prevent fixed pattern output, and optionally changing seed values for pseudo-random pattern generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If OTN maintenance signals are scrambled using fixed patterns, then the signals can be processed efficiently, but the fixed pattern output causes degradation of transmission characteristics when mapped to multilevel signals
Solution Approach 1:
The patent applies dynamics by making the scrambling pattern variable rather than fixed. The phase shifting mechanism dynamically changes the scrambling pattern based on the transmission frame number, transforming the static scrambling process into a dynamic one that adapts to different transmission conditions and prevents fixed pattern output while maintaining processing efficiency
Solution Approach 2:
The patent changes the parameter of the scrambling pattern from a fixed value to a variable value that depends on the frame number. By introducing frame number dependency into the scrambling pattern generation, the system maintains efficient processing while avoiding the harmful fixed pattern output that degrades transmission characteristics
2Speed
If multiple OTUk frames are time-division multiplexed and mapped to multilevel signals, then high-speed transmission is achieved, but fixed patterns in maintenance signals cause performance degradation
Solution Approach 1:
The patent makes the scrambling pattern dynamic by incorporating the frame number into the phase shifting calculation. This dynamic adjustment ensures that even when multiple OTUk frames are multiplexed at high speeds, the scrambled patterns remain variable and do not produce fixed output patterns that would degrade transmission performance
Solution Approach 2:
The patent uses periodic phase shifting based on frame numbers to create a cycling scrambling pattern. This periodic action ensures that the scrambling pattern repeats in a controlled manner that prevents fixed pattern output while maintaining the efficiency of high-speed time-division multiplexed transmission
Data Source
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AI summary
Provided is an optical transmission device for transmitting and receiving a multilevel-modulated optical signal, including: a plurality of transmission frame processors (212 to 214, 222 to 224) for generating transmission frame signals accommodating a plurality of client signals that are each subjected to error correction processing and scrambling/descrambling processing; and a digital modulator/demodulator (215) for mapping the transmission frame signals that are input to and output from the plurality of transmission frame processors to a multilevel signal and performing digital modulation/demodulation, in which the plurality of transmission frame processors each have a function of shifting a phase of a pattern between a plurality of transmission frames to be mapped to a multilevel signal and be digitally modulated/demodulated.