Optical Network Failure Recovery via Parallel Ranging
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Solution Overview
Problem
In passive optical networks, the conventional GPON type B architecture requires a time-consuming re-ranging process for ONUs when a malfunction occurs, prolonging the recovery time due to sequential re-configuration by the backup PON LT.
Innovation Solution
The method involves calculating and sorting round-trip delay (RTD) values for ONUs, adjusting start and stop times in the bandwidth map to prevent collisions during the re-ranging process, allowing the backup OLT to quickly determine new equalization delay values and complete re-ranging within a single GTC frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional GPON type B architecture uses backup PON LT for failure recovery, then network reliability is improved, but recovery time is prolonged due to sequential re-ranging process
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing equalization delay (EqD) values for all ONUs during normal operation. When a PON LT fails, the backup PON LT can immediately retrieve these pre-stored EqD values and perform parallel re-ranging without sequential processing, significantly reducing recovery time while maintaining reliability
Solution Approach 2:
The system uses the existing EqD values that were previously measured and stored by the network itself. The backup PON LT leverages these self-generated historical data to expedite the re-ranging process, eliminating the need for time-consuming new measurements of all ONUs from scratch
2Reliability
If backup PON LT performs sequential re-ranging of all ONUs, then ranging collision is avoided, but productivity is reduced due to time-consuming process
Solution Approach 1:
The patent changes the parameter of ranging time allocation by adjusting start and stop times in the bandwidth map based on pre-calculated EqD values. This allows multiple ONUs to perform ranging operations in parallel within a single GTC frame without collision, simultaneously improving productivity while maintaining reliability through parameter optimization
Solution Approach 2:
The patent transitions from sequential re-ranging (one-dimensional time processing) to parallel re-ranging by utilizing the EqD value dimension. By calculating time offsets based on EqD values, the system schedules multiple ONUs to transmit ranging responses simultaneously in different time slots within the same GTC frame, achieving collision-free parallel processing
Data Source
AI summary
An optical network failure recovery method for a passive optical network is provided. The method includes steps of: obtaining at least one round-trip delay value according to an equalization delay value of at least one optical network unit with respect to an operating optical line terminal; sorting the round-trip delay values in an increasing order and obtaining a minimum round-trip delay value; obtaining at least one difference between the minimum round-trip delay value and the round-trip delay value of each of the optical network units; and adjusting a start time and a stop time in a bandwidth map for a ranging response message replied by each of the optical network units according to the at least one difference.