OTN Time Delay Calibration via TDR Reflection Measurement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed optical signals in OTN systems experience differential time delay or skew due to modulation techniques, making it difficult to recover serial streams from parallel streams, especially with the transition from 1 bit per symbol to 2 bits per symbol in 100 Gbps protocols.
Innovation Solution
The system employs time domain reflectometry (TDR) to measure signal reflections and adjust time delay modules in each signal path, minimizing time delay differences between complex envelope channel components within and between polarization branches, using 2n-PSK and 2p-PSK modulated signals to calibrate for skew errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If parallel fashion transmission at bit-rate greater than 100 Gbps is used, then signal transmission speed is improved, but differential time delay or skew increases making recovery of serial streams difficult
Solution Approach 1:
The patent applies preliminary action by performing TDR measurements and skew calibration before actual data transmission. The system measures differential time delay between parallel paths using TDR and adjusts time delay modules to equalize skew before serial stream recovery, preventing the skew problem from degrading transmission performance
Solution Approach 2:
The patent implements feedback by using TDR measurements to continuously monitor differential time delay between parallel signal paths and automatically adjusting time delay modules based on measured skew. The system measures reflections from output ports, calculates time delay differences, and feeds this information back to adjust equalization, creating a closed-loop control system that maintains precise time synchronization
2Productivity
If 2n-PSK and 2p-PSK modulated signals are used with multiple parallel paths, then transmission capacity is improved, but measurement and calibration complexity increases
Solution Approach 1:
The patent applies universality by using a single TDR measurement system that can calibrate multiple parallel paths (Ix, Qx, Iy, Qy) simultaneously. The same TDR methodology and time delay adjustment approach is universally applied to all parallel signal paths, reducing calibration complexity despite increased transmission capacity requirements
Solution Approach 2:
The patent applies segmentation by dividing the calibration process into separate measurements for each parallel path (Ix, Qx, Iy, Qy). The TDR system measures reflections from each path individually, allowing independent characterization and adjustment of time delay for each segment, which simplifies the overall calibration of the multi-path system
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 effectively controls time delay and minimizes skew errors in multichannel OTN transmission devices, enabling accurate recovery of serial streams from parallel streams by adjusting time delay modules based on reflection measurements, thereby enhancing signal transmission reliability and accuracy.
Implementation Method 1
The system employs time domain reflectometry (TDR) to measure signal reflections and adjust time delay modules in each signal path
Data Source
AI summary
A system and method are provided for controlling time delay in a multichannel optical transport network (OTN) transmission device using time domain reflectometry (TDR) measurements. The method accepts a pair of 2n-phase shift keying (2n-PSK) modulated signals via Ix and Qx electrical signal paths, where n>1. Likewise, a pair of 2p-PSK modulated signals are accepted via Iy and Qy electrical signal paths where p>1. Using TDR modules, signal reflections are measured from an output port for each signal path. The method minimizes time delay differences in the signal reflections for the Ix, Qx, Iy, and Qy signals paths by using the signal reflection measurements to adjust time delay modules in each signal path.