TWDM PON Equalization Delay Invariance
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Solution Overview
Problem
In Time and Wavelength Division Multiplexing (TWDM) Passive Optical Network (PON) systems, the switching of wavelength channels by Optical Network Units (ONUs) leads to service interruptions and timing overhead due to the need for repeat ranging procedures, as round-trip optical signal propagation times differ across various wavelength channels.
Innovation Solution
Implementing a method where Optical Line Terminal (OLT) channel terminations agree on a global zero-distance equalization delay, allowing ONUs to maintain invariant equalization delay across multiple wavelength channels by handover procedures, eliminating the need for repeat ranging when switching between wavelength channels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If wavelength channel switching is implemented in TWDM PON systems, then network capacity and flexibility are improved, but service interruptions and timing overhead occur due to repeat ranging procedures
Solution Approach 1:
The patent applies preliminary action by establishing a global zero-distance equalization delay parameter before wavelength channel switching occurs. This pre-configured parameter allows the ONU to maintain correct timing information across wavelength transitions without requiring repeat ranging procedures, thereby eliminating service interruptions and reducing timing overhead when switching between wavelength channels.
2Measurement precision
If repeat ranging procedures are performed when switching wavelength channels, then timing accuracy is maintained, but service interruptions occur
Solution Approach 1:
The patent implements feedback by using the global zero-distance equalization delay parameter to continuously maintain timing accuracy across wavelength channel transitions. This feedback mechanism allows the system to preserve timing information without requiring repeat ranging procedures, thereby maintaining service continuity while ensuring timing precision.
3Reliability
If channel-invariant equalization delay is maintained across multiple wavelength channels, then service interruptions are eliminated, but system complexity increases
Solution Approach 1:
The patent applies universality by creating a global zero-distance equalization delay parameter that serves multiple wavelength channels universally. This single parameter configuration enables the system to maintain consistent timing across all wavelength channels without requiring separate equalization delay configurations for each channel, thereby reducing overall system complexity while ensuring service continuity.
Data Source
AI summary
A device determines a zero-distance equalization delay and an order for optical line terminal (OLT) channel terminations (CTs), and determines a round-trip propagation time between a first OLT CT, based on the order, and an optical network unit (ONU). The device determines an equalization delay based on the round-trip propagation time, and hands over the ONU to a next OLT CT. The device calculates a round-trip delay for the next OLT CT based on a propagation time between the next OLT CT and the ONU, a processing time of the ONU, and the equalization delay. The device compares the round-trip delay, for the next OLT CT, with the zero-distance equalization delay to obtain a comparison result, and alters the zero-distance equalization delay based on the comparison result. The device repeats the performing, the calculating, the comparing, and the altering for remaining OLT CTs.