Optical Transmitter XPM Pre-equalization Multi-span
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current optical communication systems face significant signal degradation due to cross phase modulation (XPM) in long-distance wavelength division multiplexing (WDM) optical communication, particularly in super channels with closely spaced wavelengths, where existing pre-equalization technologies only address XPM in the first span and not subsequent spans, and sharing data waveform information across all channels increases data capacity impractically.
Innovation Solution
An optical transmission apparatus with transmitters that compute and share data waveform information across multiple spans to pre-equalize XPM, using digital signal processors (DSPs) to generate and apply inverse matrices for XPM compensation, effectively reducing signal degradation across multiple spans while accounting for polarization crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data waveform information regarding signals of all channels is shared to pre-equalize XPM in multiple spans, then signal quality is improved, but data capacity increases making it impractical
Solution Approach 1:
The patent extracts only the necessary data waveform information related to XPM effects from the full channel signals. Instead of sharing complete data waveform information which would increase data capacity, the system extracts and shares only the specific parameters needed for XPM pre-equalization, such as amplitude and phase characteristics that cause XPM, thereby maintaining signal quality while avoiding impractical data capacity increases
Solution Approach 2:
The patent applies partial action by implementing pre-equalization for multiple spans (exceeding the conventional single-span approach) but only for the specific XPM-related parameters rather than complete data waveform information. This partial approach to information sharing achieves multi-span XPM compensation without the excessive data capacity requirements of full information sharing
2Reliability
If existing pre-equalization technology is used, then XPM in the first span is compensated, but XPM in the second and subsequent spans is not addressed
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-equalizing XPM effects for multiple spans before signal transmission. The system computes the cumulative XPM effects across all spans and applies compensatory phase adjustments in advance, enabling compensation for second and subsequent spans that conventional single-span technologies cannot address
Solution Approach 2:
The patent enhances adaptability by creating a universal pre-equalization framework that can compensate for XPM effects across any number of spans. The system is designed to handle both single-span and multi-span scenarios, making it versatile for different network configurations while maintaining improved signal quality through comprehensive XPM compensation
3Productivity
If closely spaced wavelengths are used in super channels, then data transmission capacity increases, but XPM degradation becomes significant
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for the XPM degradation that will occur during transmission of closely spaced wavelength channels. The system calculates the expected XPM phase shifts based on the super channel configuration and applies opposite phase adjustments before transmission, counteracting the harmful XPM effects and enabling high-capacity data transmission without significant degradation
Solution Approach 2:
The patent manages the trade-off by dynamically adjusting transmission parameters such as launch power levels and channel spacing optimization for super channels. The system modifies these parameters to minimize XPM degradation while maintaining high data transmission capacity, allowing closely spaced wavelengths to be used effectively with reduced harmful effects
Data Source
AI summary
An optical transmission apparatus includes transmitters configured to correspond to the polarization multiplexing optical signals, each of at least two of the transmitters including a first computing unit that computes, based on information regarding an optical transmission line including a plurality of spans and a polarization multiplexing optical signal, data waveform information regarding the transmitter and transmits the data waveform information to at least one another transmitter provided for at least one another polarization multiplexing optical signal, and a second computing unit that receives data waveform information from the at least one another transmitter provided for the at least one another polarization multiplexing optical signal and pre-equalizes or reduces cross phase modulation occurring in the optical transmission line of a transmission signal based on the data waveform information received from the at least one another transmitter provided for the at least one another polarization multiplexing optical signal.