Fibre Characterisation and FTTx - Fhi · deployed on a new build or existing fiber ... The basic...

Fibre Characterisation and FTTxNew challenges New challenges

Nicolas CARLIERNicolas CARLIERFrance & Benelux RSMFrance & Benelux [email protected]@exfo.com

Broadband Technology EventBroadband Technology EventRotterdam, November 10th, 2009Rotterdam, November 10th, 2009

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Regardless if the services are to be deployed on a new build or existing fiber network, a series of measurements need to be performed to certify the link is appropriate for use.

The suite of measurements performed are known as “Fiber Characterisation”. The specific requirements are identified by ITU-T SG15 ref: G.650.3

What is Fiber Characterisationwhen is it used, what is its worth?



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Higher speed services are not a case of plug and play. The physical layer (fiber) needs to be properly characterised to ensure the services can be deployed. Examples: FTTH, 10G, 10GbE, DWDM, 40G, 100G

Adopting an appropriate FC strategy is “mission critical” to the operator. Failure to do so will mean an inability to deploy the service in a timely manner costing $$$ and competitive advantage.



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The scope of these measurements may differ, but according to G.650.3

These measurements are needed to verify if the network or link is capable of delivering the required service

Their purpose is to ensure the network has been: 1) installed correctly with good splicing, handling and cleanliness 2) the fibre has the ability to carry high bandwidth services.

If these parameters are not met there can be a catastrophic effect on the transmission speed, resulting in delays of operation and the inability to not use high speeds.

Therefore, Fibre Characterisation becomes vitally important.




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What Does G.650.3 Recommend?

The basic set of “Tier 1” tests consist of:• Connector end faces (clean and scratch-free) – essential for low loss and future issues on the network• Bidirectional OTDR – quality of the splicing, handling and cleanliness of the fibre installation.• Bidirectional OLTS (sometimes called ILM) – required to perform a final functional check that the “power budget” is within specification/operating limits



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ILM/ORL solution

An ILM/ORL set certifies whether the overall link will satisfy design criteria Highly time consuming and prone to operator error Accuracy and good practice are key to reliable data collection – automation is key

Source Power meter



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OTDR solution

An OTDR is used to confirm that the fibers, splicing and connectors in a system are within the specified tolerance. This shows a good quality installation and this should therefore allow the system budget to be in specification.

Total Link Loss & Reflectance - OTDR

ONT

OLT

F1

F2FTB-200

No transmission



FTTx specificities

Broadband Technology EventBroadband Technology EventRotterdam, November 10th, 2009Rotterdam, November 10th, 2009



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Typical FTTx Topologies Examining the Differences

Point to point

PON

Active Ethernet

Splitter

Switch



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New architecture trend: MDU (Multi Dwelling Unit)

Vertical/Medium/High rise MDU

Horizontal/Garden style MDU



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FTTx – Specificities

1. Multiple connections (connectors or splices)

2. Splitters, single or double stage up to 1x64 (up to 20dB loss)

3. Closely spaced events: Typically 3 spans from FDH between 50m and 500m

4. Mixture of standard SMF-28 and bend insensitive fibers

5. Macrobends



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Multiple connections - Splitters

Splitter

Splice tray

Patch panel C.O. Patch panelEnd of link

OLT

Drop terminal

Splice trayC.O.

FTB-200



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Closely spaced events

Fiber CollectorPatch panel

C.O. Patch panel

OLT

FTDDrop terminalFDH

Splice tray

C.O.

OTDR

ON

T

Few hundred meters to several km

~ 100m ~ 10m ~ 10m



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SMF-28 and Bend insensitive fibers

The only way to qualify those splices is to measure in both directions and average



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Macrobends



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Main Tech Pains with standard OTDR

Can’t differentiate closely spaced events--> standard OTDRs lack of resolution at higher pulses

Can’t measure a splitter loss with accuracy --> standard OTDRs lack of dynamic range at lower pulses

Can’t locate problems on F1 fiber passed the splitter --> standard OTDRs lack the resolution at higher pulses = long DZ

Can’t troubleshoot one customer without disconnecting from the network --> Live fiber testing requires a filtered and out-of-band OTDR

CONCLUSION: standard OTDRs are not adapted for FTTx characterization



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1:32 splitter, 275ns, 15 sec averaging time

55 meters dead zone

Standard OTDR

High dynamic range OTDRFTTx OTDR

A picture worth a thousand tests



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Measurements in Active Networks

OTDR tests require no transmission signal on the fibre (dark fibre)• Max tx signal power still allowing OTDR acquisition: - 45 dBm• Max signal before damaging APD: - 20 dBm

=> That section of the PON has to be turned off, affecting other customers

OTDR with out of band filtered port allows testing of branches without disturbing other customers.

**ITU-T Recommendation L66: 1625-1675 nm Maintenance band. 1650 nm Monitoring wavelength



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FTTH Service-Activation

IPTV

RF

PON (Passive)

Active EthernetSwitching

F1

F2

EthernetSwitch

Continuous wave (CW) signal

Burst signal

At the subscriber’s premises1. Install and power up ONT2. Connect/splice drop cable3. Measure optical signal



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Cleaning Connectors Cleaning is one of the most neglected operations but it is the most important one 75% of network problems are related to connectors Permanent damage can occur on dirty connectors when high power signal is turned on. Remember also to clean the connector which you connect to. This must be done at

LT,NT, ONT, splitter and ODF. All connectors MUST be clean before they are inserted. ICI!!!!!!!

In addition – dirty connectors give high reflectance – high reflectance can « kill » an OTDR trace!

Dirty connectorClean connector Permanantly damaged



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Inspecting connectors

Using a video inspection probe is the safest way to inspect connectors



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SUMMARY : What to test, when ?

• Construction• check cables/fibers OTDR / OLTS• check splices and connectors OTDR• check continuity VFL• inspect connectors Inspection Probe

• Activation• inspect connectors Inspection Probe• check power level Power meter (standard or PON)

• Troubleshooting• inspect connectors Inspection Probe• check power level PON Power Meter• locate default OTDR / Filtered OTDR



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EXFO’s solutions for FTTx

Powemeter PPM-350COLTS FOT-930 MaxTester

Loss, length, ORL

FTTx/Access OTDR AXS-100/AXS-110

Mainframe FTB-200FTTx OTDR FTB-7300EOLTS FTB-3930

Inspection probe :Option for FOT-930, FTB-200, AXS-100/AXS-110,

or available as stand alone unit



Questions?

Meet us at CN ROOD’s booth



Fibre Characterisation and FTTx - Fhi · deployed on a new build or existing fiber ... The basic...

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