Passive Optical Network Quiet Window Allocation for Signal Collision Avoidance
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Solution Overview
Problem
In passive optical networks (PONs), the existing quiet window management system fails to simultaneously satisfy the loop delays of ONUs farthest and closest to the OLT, leading to signal collisions and inefficient bandwidth usage, particularly when range extenders are introduced to extend communication distances beyond 20 km.
Innovation Solution
The method involves determining and allocating distinct quiet windows for ONUs within different preset distance ranges, ensuring that the quiet windows account for the varying loop delays between the OLT and ONUs, thereby reducing signal collisions and improving uplink transmission efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single quiet window is used for all ONUs, then the system structure is simple, but signal collisions occur between ONUs at different distances
Solution Approach 1:
The patent divides the ONU population into multiple groups based on their distance from the OLT (first preset distance range and second preset distance range). Each group is assigned a separate quiet window (first quiet window and second quiet window), allowing simultaneous registration without signal collision. This segmentation resolves the contradiction by trading increased management complexity for reliable collision-free operation.
2Reliability
If the quiet window is extended to accommodate farthest ONUs, then registration success rate improves, but uplink bandwidth efficiency decreases
Solution Approach 1:
By segmenting ONUs into distance-based groups with separate quiet windows, each window can be optimized for its specific group's loop delay characteristics. This eliminates the need to extend the quiet window to accommodate the farthest ONU, thereby maintaining registration success rate while preserving uplink bandwidth efficiency for other transmissions.
Solution Approach 2:
Each quiet window is configured with parameters (start time, duration) specifically tailored to the local characteristics of its associated ONU group's distance and loop delay. This local optimization ensures that each quiet window is just long enough for its group, avoiding the waste that would result from a universally extended window.
3Length of stationary object
If range extender is added to extend communication distance, then coverage range increases, but signal collision probability increases
Solution Approach 1:
The patent segments the network into multiple ODNs with range extenders, where each ODN's ONUs are assigned specific quiet windows. This segmentation allows the system to extend communication distance through range extenders while maintaining low collision probability by ensuring that ONUs in different ODNs do not contend for the same time slot.
Solution Approach 2:
The range extender acts as an intermediary that not only extends signal reach but also serves as a boundary for quiet window allocation. By associating specific quiet windows with specific ODNs (separated by range extenders), the system manages the extended range while preventing signal collisions between distant ONUs.
Data Source
AI summary
Provided are a method for managing an ONU in a passive optical network, an OLT and a system. The method includes determining a first quiet window and a second quiet window, and allocating the first quiet window to an ONU within a first preset distance range and allocating the second quiet window to an ONU within a second preset distance range, where the distance between the optical line terminal (OLT) and the ONU within the first preset distance range is less than the distance between the OLT and the ONU within the second preset distance range.