Optical Data Reception Using LFMS Reflection Cancellation
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Solution Overview
Problem
In same-wavelength single-fiber bidirectional optical communication systems, Fresnel reflection generates crosstalk signals that cannot be filtered out due to shared frequency bands, leading to degraded communication quality due to time differences in signal arrival.
Innovation Solution
A data receiving method that utilizes linear frequency modulated sequences to determine a time-domain offset, allowing reconstruction and elimination of reflected crosstalk signals from mixed signals, improving communication quality by reducing the impact of time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If Fresnel reflection is utilized for bidirectional communication, then communication capacity is doubled, but reflected crosstalk signal degrades signal quality
Solution Approach 1:
The patent converts the harmful reflected crosstalk signal into a useful component by reconstructing it from the known transmitted signal and subtracting it from the received mixed signal. This eliminates the crosstalk interference while maintaining the bidirectional communication capability, effectively turning the harmful reflection into a manageable element that can be removed through signal processing.
Solution Approach 2:
The patent extracts and removes the reflected crosstalk signal from the received mixed signal by reconstructing it based on the transmitted signal characteristics. This separation allows the desired signal to be recovered without the harmful reflection component, resolving the contradiction between utilizing reflection for capacity and eliminating its harmful effects.
2Object-affected harmful factors
If reflected crosstalk signal is eliminated by filtering, then signal quality improves, but filtering is ineffective due to same frequency band
Solution Approach 1:
Instead of attempting to filter the crosstalk signal in the frequency domain (where both signals occupy the same band), the patent transitions to the time domain for signal separation. By determining time-domain offsets and using temporal information, the patent achieves crosstalk elimination through a different dimensional approach that bypasses the limitations of frequency-domain filtering.
Solution Approach 2:
The patent replaces the physical filtering mechanism (which cannot separate same-frequency signals) with a computational signal processing approach. By using mathematical operations to reconstruct and subtract the crosstalk signal based on time-domain analysis, the patent substitutes hardware filtering with software-based signal manipulation that achieves the desired separation.
3Device complexity
If time difference between signals is not compensated, then system complexity is low, but communication quality degrades
Solution Approach 1:
The patent performs preliminary determination of the time-domain offset between the transmitted signal and the reflected crosstalk signal before conducting signal elimination. This advance preparation allows the system to accurately align and subtract the crosstalk component, improving communication quality without requiring complex real-time processing during signal reception.
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
The method effectively eliminates reconstructed data frames from mixed signals, enhancing communication quality by improving accuracy and reducing the impact of time differences between signal arrivals.
Implementation Method 1
Fresnel reflection is generated when the system has a connector end face of an optical fiber
Data Source
AI summary
A method includes: a first device sends a first data frame to a second device, where the first data frame includes an LFMS a1; the first device receives a mixed signal, where the mixed signal includes a first reflected data frame of the first data frame and a second data frame sent by the second device; the first device obtains a first offset based on the LFMS a1 in the first reflected data frame, and obtains a reconstructed data frame of the first reflected data frame based on the first data frame; and the first device eliminates the reconstructed data frame of the first reflected data frame from the mixed signal based on the first offset.