Passive Optical Network Ranging via Round Trip Delay
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Solution Overview
Problem
In Gigabit Passive Optical Networks (GPON), the long open time of the quiet window during ranging interrupts normal service for operational ONUs, affecting upstream transmission efficiency, as the OLT must guess the nearest and furthest distances to determine the quiet window duration.
Innovation Solution
Obtain the Round Trip Delay (RTD) between the OLT and ONU, and use this to determine a shorter quiet window duration for ranging, thereby optimizing the quiet window's open time and improving upstream transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the OLT opens a quiet window with a long duration to perform ranging on ONU, then the ranging can be completed successfully, but the normal upstream transmission of operational ONUs is interrupted, reducing upstream transmission efficiency
Solution Approach 1:
The OLT performs preliminary actions by sending a ranging request message and opening a quiet window before the actual ranging measurement. The quiet window is opened in advance to ensure that no upstream data packets are transmitted during the ranging process, preventing packet loss and ensuring accurate ranging results. This preliminary preparation allows the ranging to complete successfully while minimizing disruption to normal operations.
Solution Approach 2:
The system dynamically adjusts the quiet window duration based on the measured round-trip delay (RTD) of the specific ONU. Instead of using a fixed conservative duration, the quiet window is optimized to match the actual propagation characteristics of each ONU, ensuring sufficient time for ranging while minimizing the interruption period for upstream transmissions.
2Adaptability or versatility
If the OLT uses a fixed conservative quiet window duration based on nearest and furthest distances, then all ONUs can be accommodated, but the quiet window duration cannot be optimized for individual ONUs, leading to unnecessary service interruption
Solution Approach 1:
The system applies local quality by customizing the quiet window duration for each individual ONU based on its specific characteristics, particularly its round-trip delay (RTD). Each ONU receives a tailored quiet window duration that matches its propagation characteristics, rather than applying a uniform conservative duration to all ONUs. This localized optimization reduces unnecessary service interruption for each ONU while ensuring adequate quiet window coverage.
Solution Approach 2:
The system changes the quiet window duration parameter dynamically for each ONU based on measured RTD values. By adjusting this critical parameter according to individual ONU characteristics, the system achieves both adaptability to different ONU positions and minimization of service interruption time, resolving the contradiction between universal accommodation and individual optimization.
Data Source
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AI summary
The present invention discloses a method for ranging in a passive optical network, and the method includes: obtaining a Round Trip Delay (RTD) between an Optical Line Terminal (OLT) and an Optical Network Unit (ONU); and opening a quiet window used for the ranging for the ONU according to the RTD to perform the ranging on this ONU. The present invention further discloses an apparatus for ranging in a passive optical network, and the apparatus includes: an obtainment module which is configured to: obtain a RTD between an OLT and an ONU; and a ranging module configured to: open a quiet window used for ranging for the ONU to perform ranging on the ONU according to the RTD. The present invention shortens the open time of the quiet window used for the ranging and improves the efficiency of the upstream transmission, and the implementation method is simple and convenient.