Fault Localization of PON

Yeung Chue Hei (1008620051)Lam Yi Kwan (1008627154)

Network Structure

FTTX (fiber to the X)

Passive (PON)Multiplexing (→P2MP)

TDM

WDM

Goals

Maintain service quality 1/3 of service disruptions are due to fiber cable Fault can be a disaster

Assisting reparation Reduce lost Efficiency

Not affecting the other service

Challenges

High resolution VS high DR capabilities

Measurement time

Point-to-multipoint problem

Solutions for TDM-PONs

P2P Active By-pass Passive By-pass Integrated OTDR functionality

P2MP Tunable OTDR and wavelength selective reflectors Conventional OTDR and controlled reference reflections Brillouin OTDR

Solutions for WDM-PONs

Tunable OTDR/multi-wavelength source and optical reflector

Re-using existing light sources

Commercial multi-wavelength OTDR

Other solutions

Optical Code-division Multiplexing

Optical Frequency Domain Reflectometry

Measuring the Individual Attenuation Distribution of Passive

Branched Optical NetworksKuniaki Tanaka, Mitsuhiro Tateda, Senior Member, IEEE,

and Yasuyuki Inoue, Member, IEEE

IEEE PHOTONICS TECHNOLOGY LETTERS, VOL 8, NO 7, JULY 1996

Reference Reflector

Reference Reflector

Conventional OTDR

Specially designed branched networks Transmission line lengths differ with each other

Cannot test branched fiber losses individually

Go to the subscriber terminals after branching and measure the transmission loss directly

Passive By-pass

“New” method

Arrayed Waveguide Grating (AWG)

Optical Splitter/Router Module

Optical Splitter/Router Module

Optical Splitter/Router Module

OTDR Configuration

OTDR Traces

Fiber Fault Identification for Branched Access Networks Using a Wavelength-

Sweeping Monitoring Source

Chun-Kit Chan, Frank Tong,Lian-Kuan Chen, Keang-Po Ho, Dennis Lam

Introduction

Conventional OTDR cannot differentiate Rayleigh backscattered light from different branches

Multiwavelength OTDR is expensive

Fiber Identification Scheme

To avoid pulse collision

(2nL/c) < 1/(Nf)

Eg. N=8, f=1kHz, n=1.5, max L=12.5km

Experiment

1 x 4 branched optical network

Data channels: 1548nm, 1551nm

1Gb/s 210-1 PRBS NRZ

L1=8.8km, L2=L3=6.6km, L4 is unmonitored

FBG: 1556.4nm, 1558nm, 1559.7nm

3dB passband: 0.4nm, 0.8nm, 0.9nm

Sawtoothed signal: 2kHz

Summary

Makes use of FBGs

No additional monitoring source

Both time and frequency domain

With OTDR techniques, can locate exact fiber cut position

Q&A

Thank you for your attention!