Optical Network Unit Activation via Subsequence Ranging
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Solution Overview
Problem
The existing ONU activation process in TDM-PON systems introduces significant latency due to the quiet window required to avoid collisions with upstream traffic, which is not suitable for latency-sensitive applications.
Innovation Solution
A method where ONUs transmit a localization sequence with unique subsequences during reserved time-windows, allowing the OLT to determine the ONU's position and round-trip time, thereby reducing the quiet window duration and minimizing interference with regular upstream traffic.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a quiet window is enforced during ONU activation to avoid collisions with upstream traffic, then collision avoidance is improved, but upstream traffic latency increases
Solution Approach 1:
The localization sequence is divided into multiple unique subsequences, where only one subsequence needs to be identified during the ranging process. This segmentation allows the quiet window to be reduced to the duration of a single subsequence rather than the entire localization sequence, thereby reducing upstream traffic latency while still ensuring collision avoidance through precise position identification.
2Measurement precision
If the duration of the localization sequence is longer than the quiet window, then positioning precision is improved, but quiet window duration must increase
Solution Approach 1:
Instead of requiring the entire localization sequence to fit within the quiet window, the system only needs to identify a single subsequence from the localization sequence during the ranging process. This partial action approach allows the use of a long localization sequence for high positioning precision while keeping the quiet window duration short (equal to subsequence duration), resolving the contradiction between precision and duration.
Data Source
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AI summary
Provided is an optical line terminal, OLT, which is enabled to range optical network units, ONU, in a time division multiplexing, TDM, passive optical network, PON, based on a position of a received subsequence within a localization sequence, wherein the duration of the localization sequence is longer than the duration of a time-window which is reserved for ranging.