Optical Multicarrier Signal Parameter Control for Spectral Efficiency
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Solution Overview
Problem
High-speed optical channels beyond 100 Gbit/s face challenges due to electronic circuit limitations and performance degradation from linear and non-linear impairments in optical fibers, limiting achievable spectral efficiency in DWDM networks.
Innovation Solution
An apparatus and method for controlling optical multicarrier signals by adjusting both Forward Error Correction (FEC) overhead and carrier bandwidth based on individual carrier transmission performance and overall spectral efficiency, allowing for finer granularity and improved capacity utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high order modulation formats (e.g., 16QAM) are used to maximize spectral efficiency, then spectral efficiency is improved, but reliability deteriorates due to performance degradation from linear and non-linear impairments in optical fiber
Solution Approach 1:
The system dynamically adapts modulation format and FEC overhead based on real-time transmission performance monitoring. The processor selects parameter values including modulation format and FEC overhead according to individual carrier transmission performance, enabling the system to transition between high-order formats (16QAM) for short links and low-order formats (QPSK) for longer or degraded links, thus resolving the contradiction between spectral efficiency and reliability
Solution Approach 2:
The invention changes physical parameters (modulation format order and FEC overhead) to optimize the balance between spectral efficiency and reliability. By adjusting these parameters based on transmission distance and channel conditions, the system can operate at high spectral efficiency when conditions permit while maintaining reliability when impairments are present
2Adaptability or versatility
If adaptive modulation format is used to adjust aggregate capacity according to propagation impairments, then adaptability is improved, but device complexity increases due to the need to monitor and adjust multiple parameters
Solution Approach 1:
The system segments the control of individual carrier parameters from the overall multicarrier signal control. The processor independently determines parameter values for each carrier based on its specific transmission performance, allowing adaptive capacity adjustment without requiring complex centralized control of the entire signal, thus reducing device complexity while maintaining adaptability
Solution Approach 2:
The system implements feedback mechanisms where transmission performance of individual carriers is monitored and used to automatically adjust modulation format and FEC overhead. This closed-loop control enables adaptability while automating the adjustment process, reducing the need for manual intervention and simplifying operational complexity
3Productivity
If carrier bandwidth is reduced to improve spectral efficiency, then spectral efficiency is improved, but transmission performance deteriorates due to increased susceptibility to impairments
Solution Approach 1:
The system changes the FEC overhead parameter to compensate for reduced carrier bandwidth. By adjusting FEC overhead in conjunction with bandwidth changes, the system maintains transmission reliability while achieving improved spectral efficiency, resolving the contradiction between these two parameters
Solution Approach 2:
The system applies FEC coding before transmission to provide error protection against impairments that become more significant with reduced bandwidth. This prior cushioning through error correction coding allows the system to use narrower bandwidths for better spectral efficiency while maintaining reliability through pre-applied error protection
Data Source
AI summary
An optical multi carrier signal has a modulation format and has many individual carrier signals. Parameters of the signal are controlled by receiving an indication of individual carrier transmission performance of the individual carrier signals, and selecting parameter values for the individual carrier signals, the parameter values comprising both a carrier FEC overhead and a carrier bandwidth for the modulation format. Selection is made according to the indicated individual carrier transmission performance and according to an overall spectral efficiency of the multi carrier signal. The selected parameter values are output for control of the optical multi carrier signal. By selecting values for both parameters rather than either one, better optimization can be obtained since they are interdependent. The control can have better granularity than changing modulation format, and can make better use of bandwidth or improve the overall capacity.