Optical Communication Backup Head End Synchronization
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Solution Overview
Problem
In protected optical communication systems, the handover from a main supply arm to a backup supply arm can be disrupted by the time-consuming initialisation routine, particularly due to the need for a ranging procedure when faults occur, leading to prolonged downtime.
Innovation Solution
The method involves using synchronisation information from the main head end unit to quickly synchronise the backup head end unit, and performing the ranging procedure for the backup repeater during normal operation of the main network, allowing the backup OLT to pre-calculate round-trip delays and reduce the need for a full ranging procedure upon handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a back up supply arm is provided for fault tolerance, then system reliability is improved, but the initialisation routine becomes excessively time consuming
Solution Approach 1:
The invention performs the ranging procedure on the back up repeater while the main supply arm is still operational. This preliminary action allows the back up head end unit to acquire synchronisation information in advance, so that when a fault occurs and handover is required, the initialisation routine can be executed much faster since the time-consuming ranging step has already been completed.
2Speed
If a ranging procedure is performed on the back up repeater during main network operation, then handover speed is improved, but network complexity increases
Solution Approach 1:
The back up head end unit autonomously performs the ranging procedure with the back up repeater during normal operation. This self-service approach enables the system to prepare for potential failover without requiring external intervention or complex control mechanisms, thereby achieving fast handover while managing complexity through automated self-configuration.
Data Source
Figure 1(a)~1(b)
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Figure 4
AI summary
This concerns a protected long-reach PON having a plurality of terminals connected to a distribution network that is fed by both a main and back up feed, each feed including a head end and a repeater. The back up head end had access to a ranging table with data previously obtained by the main head end, thereby speeding up the switch over in the event of a fault with the main feed. In one embodiment, the repeater has a virtual ONU therein, allowing the back up repeater to be ranged by the back up head end, thereby yet further speeding up the ranging procedure. The main and back up repeaters are sufficiently equidistant from the distribution network to allow the back up head to perform normal scheduling without performing a ranging operation on each of the terminals, even if the different terminals transmit at slightly different wavelengths. This is achieved using the ranging information obtained with regard to the back up repeater.