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FTTx/G-PON Testing
As optical networks have started to spread from their use in trunk networks into the latest technologies such as FTTx and G-PON new requirements for testing have evolved. Traditionally Optical Time Domain Reflectometers (OTDR) have been used for Point to Point testing between nodes and exchanges but with the rollout of FTTx networks new methods of testing have had to be implemented. Various implementations of FTTC, FTTB and FTTH are currently being installed worldwide and verification and restoration of the network has become an issue.
When the customer reports a problem it is usual practice to dispatch an engineer equipped with an OTDR to the premises to test the fibre back to the exchange to find any fault conditions. It is not unusual for the engineer to find there is no problem with the fibre but that the problem is with the subscribers’ equipment. Truck rolls and wasted manpower results in an increase in OpEx.
A new method of testing has evolved to take into account the problems caused by the use of splitters in a G-PON network when testing from the Central Office (CO). UTEL have designed a fibre test system made up of two components, a CO based OTDR and an Optical Test Access Switch.
Optical fibre lines can be tested prior to dispatching an engineer. If no fault is detected on the fibre the subscriber can be informed that the problem is with their equipment and that an engineer could attend to rectify the problem for a fee. This not only reduces OpEx but introduces a new revenue stream for the Communication Provider.
Both the Optical Switch and OTDR are based in the Central Office, control of the equipment can be performed by the Communication Providers own OSS (via XML or TL1) or UTEL's bespoke test management software. When a fault is reported the Operations Centre would, via the OSS, connect to the Optical Switch and select the appropriate fibre which is then automatically connected to the OTDR. Tests would then be initiated and the results automatically returned to the Operator.
Various levels of presentation are available to the operator performing the test action. At a deskilled operator level it can be a simple "traffic lights" indicator or for a skilled engineer it can present detailed OTDR traces.
UTEL Optical Switch-32
An expandable Optical Test access switch enabling connection to 32 fibres via a WDM
Further details >>
OTDR