Optical Communication System Transfer Function Estimation
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Solution Overview
Problem
Current digital coherent transmission systems face challenges in reducing the delay associated with obtaining a transfer function for correcting distortion, which hinders further reduction in transmission delays and increased transmission capacities.
Innovation Solution
The optical communication system transmits pilot data through a channel with the shortest delay time to estimate the transfer function, which is then applied to other channels, reducing the signal processing load and delay by using a single light source and modulators to synchronize pilot and transmission data, and employing coherent detection with a local oscillator light beam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If digital coherent transmission technique is used to correct signal distortion through digital signal processing, then transmission capacity increases exponentially, but signal processing load and delay time increase
Solution Approach 1:
The patent segments the signal processing tasks by separating transfer function estimation from demodulation. The estimation unit acquires transfer functions for multiple channels, while demodulation units apply these pre-acquired functions. This segmentation allows parallel processing and reduces the critical path delay, as demodulation can proceed without waiting for real-time estimation completion.
Solution Approach 2:
The patent implements preliminary action by acquiring transfer functions in advance before actual data demodulation begins. The estimation unit pre-processes multiple channels to obtain transfer functions, which are then stored and reused during demodulation. This eliminates the need for real-time estimation during data processing, significantly reducing signal processing delay.
2Measurement precision
If transfer function estimation is performed for each transmission channel, then signal distortion correction accuracy is maintained, but signal processing load increases
Solution Approach 1:
The patent makes the acquired transfer functions universal by applying them across multiple transmission channels. The estimation unit generates transfer functions that are then reused by multiple demodulation units for different channels. This multi-functional approach maintains correction accuracy while eliminating redundant estimation processing for each channel.
Solution Approach 2:
The patent uses copying by replicating the acquired transfer functions across multiple demodulation units. Instead of independently estimating transfer functions for each channel, the system copies the pre-acquired functions to multiple demodulation units, reducing processing load while maintaining the ability to correct distortion across all channels.
3Productivity
If transmission band is expanded to increase capacity, then more channels are needed, but delay time in obtaining transfer functions increases
Solution Approach 1:
The patent segments the processing architecture into one estimation unit serving multiple demodulation units. This segmentation allows the system to handle multiple channels simultaneously without proportionally increasing the critical path delay, as the estimation function is performed once and shared across all channels.
Solution Approach 2:
The patent performs preliminary acquisition of transfer functions for all channels before data demodulation begins. This preliminary action ensures that even as the transmission band expands to include more channels, the delay penalty is paid once during the estimation phase, not repeatedly during data processing for each channel.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach significantly reduces signal processing load and delay by acquiring and diverting the transfer function to other channels, maintaining demodulation quality across varying transmission delay times and distances, thereby enhancing transmission capacity and reducing processing time.
Implementation Method 1
N receivers connected to the N transmission channels in a one-to-one manner and configured to receive the optical signals transmitted through the corresponding N transmission channels by performing coherent detection with single local oscillator light beam
Data Source
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AI summary
An objective of the present invention is to provide an optical communication system and an optical communication method that can reduce even a delay generated in processing of obtaining a transfer function for correcting distortion in digital coherent transmission. In the optical communication system according to the present invention, pilot data for estimating a transfer function for a transmission channel is transmitted through a transmission channel with a short transmission delay time, a transfer function of the transmission channel is estimated before receiving transmission data, and the transfer function is applied to other transmission channels.