OTUk Frame Recovery via Lane Sequence Alignment
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Solution Overview
Problem
In high-order modulation and coherent receiving systems for 100 G optical transport networks, random birefringence in optical fibers causes crosstalk between orthogonal polarization states, leading to incorrect signal recovery due to changing proportions of original and crosstalk signal components, which existing electrical equalization methods struggle to accurately track and correct.
Innovation Solution
A method and device for recovering OTUk frames using multi-lane distribution, where optical signals are converted into electrical signals, electrically equalized, and demodulated, with data alignment and rearrangement based on lane sequence identifiers in the overhead frame headers, and feedback control is applied to the equalizer algorithm to adapt to changing polarization states without the need for additional training sequences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If electrical equalization is used to eliminate crosstalk components, then signal recovery accuracy is improved, but the system cannot adapt when crosstalk proportion exceeds original signal proportion
Solution Approach 1:
The patent applies feedback control by detecting the proportion of original signal component versus crosstalk signal component in the received electrical signal, and dynamically adjusting the equalization algorithm based on this feedback. When the detected proportion indicates that crosstalk dominates, the system switches to an alternative equalization strategy, ensuring continuous accurate signal recovery under varying polarization conditions.
Solution Approach 2:
The patent implements dynamic adaptation by making the equalization process adjustable in real-time according to the actual signal conditions. The system continuously monitors the signal characteristics and modifies the equalization parameters or algorithm selection based on the current polarization state, transforming a static equalization approach into a dynamic one that can handle random birefringence effects.
2Productivity
If multi-lane distribution is used for OTUk frame transmission, then bandwidth efficiency is improved, but lane misalignment due to polarization changes causes recovery errors
Solution Approach 1:
The patent uses feedback control to detect lane sequence identifiers in the received signal and compares them with the expected sequence. When misalignment is detected due to polarization changes, the system generates feedback to adjust the lane ordering, ensuring correct frame reconstruction while maintaining multi-lane distribution benefits.
Solution Approach 2:
The patent performs preliminary detection of lane sequence identifiers before frame reconstruction. By identifying and verifying the correct lane sequence in advance, the system prepares the data in the proper order for frame assembly, preventing recovery errors even when polarization changes occur during transmission.
3Device complexity
If traditional equalization methods are used, then system complexity is kept low, but additional training sequences are required which increase overhead
Solution Approach 1:
The patent makes the overhead frame header serve multiple functions: it not only carries standard OTN management information but also contains lane sequence identifiers that enable lane alignment detection and equalization control. This multi-functionality eliminates the need for separate training sequences, reducing overhead while maintaining system capabilities.
Solution Approach 2:
The patent enables the overhead frame header to perform dual roles: traditional OTN management functions and lane sequence identification for equalization control. By making the existing overhead structure multi-functional, the system avoids adding separate training sequences, thereby reducing signal overhead without increasing system complexity.
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 ensures accurate recovery of OTUk frames even when the equalizer cannot quickly track polarization changes, avoiding inconsistencies and maintaining system performance without increasing complexity or bandwidth requirements.
Implementation Method 1
converting the optical signal into an electrical signal
Implementation Method 2
the first received electrical signal and the second received electrical signal are processed by digital filters of different coefficients (Hxx, Hxy, Hyx, and Hyy), to acquire the equalized first received electrical signal and the equalized second received electrical signal
Implementation Method 3
an OTU4 bit stream passes through a 100 G optical module and is converted into an optical signal for transport
Implementation Method 4
The first transmitted optical signal Xout and the second transmitted optical signal Yout are combined by a combiner into one optical signal
Implementation Method 5
the combined optical signal is split by a splitter into a first received optical signal X'in and a second received optical signal Y'in
Data Source
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AI summary
A method for recovering an OTUk frame includes: receiving an optical signal sent by using a method of multi-lane distribution from the OTUk frame to an interface of an optical module; converting the optical signal into an electrical signal, performing electrical equalization and demodulation on the electrical signal, and recovering multi-lane data from the demodulated signal; aligning and rearranging the data on each lane, according to a lane sequence identifier included in an overhead frame header of the data on each lane; and recovering the OTUk frame according to the aligned and rearranged data. According to the present invention, lane rearrangement is performed by detecting the lane sequence identifier, and the recovery of the OTUk frame is achieved. Therefore, a training sequence overhead does not need to be additionally introduced, and the influence on the system performance is avoided.