Subcarrier Power Balance Control in Optical Channels
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Solution Overview
Problem
In optical communication systems using multiple subcarrier channels, the bit error rate (BER) is dominated by the signal-to-noise ratio (SNR) of the subcarrier with the lowest optical power, necessitating equalization of subcarrier power levels to improve system performance.
Innovation Solution
A method is implemented where a dither signal is applied to each subcarrier, and its quality metric is detected to estimate and adjust the optimum power level, ensuring balanced power levels across subcarriers to optimize the bit error rate (BER) of the optical channel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multiple subcarrier lights are used within a spectral band, then data transmission capacity is improved, but the bit error rate increases due to unequal power levels among subcarriers
Solution Approach 1:
The patent applies local quality by individually adjusting the power level of each subcarrier light based on its specific characteristics and detected quality metrics. The transmitter modem modifies the power level of each subcarrier separately to achieve equalization, ensuring that each subcarrier contributes equally to the overall signal quality, thereby resolving the BER issue while maintaining multi-subcarrier transmission capacity.
Solution Approach 2:
The patent implements feedback control by having the receiver modem detect quality metrics for each subcarrier and feed this information back to the transmitter modem. The transmitter then uses this feedback to adjust the power levels of individual subcarriers, creating a closed-loop system that continuously optimizes power distribution to maintain equal power levels across all subcarriers.
2Reliability
If individual subcarrier power levels are adjusted to equalize power, then bit error rate is improved, but system complexity increases due to additional control mechanisms
Solution Approach 1:
The patent applies universality by implementing a standardized power control mechanism that can be applied to any subcarrier within the optical channel. The same dither signal application and quality metric detection process is used for all subcarriers, creating a universal control approach that simplifies the overall system architecture while enabling individual power adjustment for each subcarrier.
Solution Approach 2:
The system implements self-service by having the receiver modem automatically detect quality metrics and the transmitter modem automatically adjust power levels based on detected conditions. The power equalization process is performed autonomously without requiring external intervention, with the system self-regulating to maintain optimal power distribution across all subcarriers.
Data Source
AI summary
A method of controlling a multiple sub-carrier optical channel of an optical communications system. The multiple sub-carrier optical channel includes at least two sub-carriers modulated with respective sub-channel data streams within a spectral range allocated to a single optical channel of the optical communications system. A transmitter modem of the optical communications system applies a respective dither signal to each sub-carrier. A receiver modem of the optical communications system detects a respective quality metric of each sub-carrier. A respective optimum power level of each sub-carrier is estimated based on the applied dither signals and the detected quality metrics. A respective power level of each sub-carrier is then adjusted in accordance with the estimated respective optimum power level of each sub-carrier.