Optical Module PTP Clock Timing Circuitry
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Solution Overview
Problem
Advanced optical modules in high-bandwidth networks introduce dynamic and unpredictable delay asymmetry, which complicates precise time synchronization between nodes, leading to inaccuracies in timing synchronization due to differences in light propagation speed and chromatic dispersion.
Innovation Solution
Implementing Precision Time Protocol (PTP) clock functionality within optical modules, including timing circuitry that mitigates delay asymmetry and establishes a common time base across optical modules, using techniques such as transparent clocks and timestamping functions, and repurposing reference clock inputs for synchronization purposes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If advanced optical modules (DCO, COBO, OIF ZR) are used to provide high bandwidth, then network capacity increases, but delay asymmetry becomes dynamic and unpredictable, degrading time synchronization accuracy
Solution Approach 1:
The patent divides the time synchronization function into separate components: a master clock providing reference time, slave clocks receiving synchronization, and intermediate optical modules that measure and report their specific delay contributions. Each module independently measures its forward and reverse path delays and reports these to the master clock, which then calculates compensated synchronization times.
Solution Approach 2:
The system implements continuous feedback loops where slave clocks report their measured delays back to the master clock, and the master clock uses this feedback to calculate compensated transmission times. This closed-loop feedback mechanism allows the system to dynamically adjust for changing delay conditions caused by advanced optical module functions.
2Ease of operation
If round trip delay measurement is used for time synchronization, then synchronization can be achieved, but delay asymmetry between forward and reverse paths causes time errors
Solution Approach 1:
The patent explicitly addresses and utilizes the asymmetry in forward and reverse path delays. Instead of assuming symmetry, the system measures the forward path delay and the reverse path delay separately, recognizes they are different, and uses this asymmetric measurement to calculate compensated transmission times that account for the delay difference.
Solution Approach 2:
The patent adds a new dimension to time synchronization by introducing intermediate measurement points within the optical modules. Rather than only measuring end-to-end delay between master and slave clocks, the system measures delay at multiple intermediate points (at each optical module), creating a multi-dimensional view of the delay path that enables more precise compensation.
3Measurement precision
If PTP clock functionality is implemented within optical modules, then time synchronization accuracy improves, but device complexity increases
Solution Approach 1:
The patent makes optical modules multi-functional by enabling them to perform both their primary function (optical signal transmission) and time synchronization measurement functions. The same optical module that transmits data signals also measures transmission delay and reports timing information, eliminating the need for separate timing measurement devices and reducing overall system complexity despite the increased functionality of individual modules.
Data Source
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AI summary
An optical module for use in an optical system is disclosed, the optical module implementing Precision Time Protocol (PTP) clock functionality therein. The optical module includes an electrical interface with the optical system; circuitry connected to the electrical interface and configured to implement a plurality of functions of functionality; an optical interface connected to the circuitry; and timing circuitry connected to the electrical interface and one or more of the plurality of functions, wherein the timing circuitry is configured to implement the PTP clock functionality.