Fault Localization of PON

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

Network Structure

FTTX (fiber to the X)Passive (PON)Multiplexing (→P2MP)

TDMWDM

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 capabilitiesMeasurement timePoint-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 reflectorRe-using existing light sourcesCommercial multi-wavelength OTDR

Other solutions

Optical Code-division MultiplexingOptical Frequency Domain Reflectometry

Measuring the Individual Attenuation Distribution of Passive

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

and Yasuyuki Inoue, Member, IEEEIEEE PHOTONICS TECHNOLOGY LETTERS, VOL 8,

NO 7, JULY 1996

Reference Reflector

Reference Reflector

Conventional OTDRSpecially designed branched networks Transmission line lengths differ with each other

Cannot test branched fiber losses individuallyGo 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 SourceChun-Kit Chan, Frank Tong,

Lian-Kuan Chen, Keang-Po Ho, Dennis Lam

Introduction

Conventional OTDR cannot differentiate Rayleigh backscattered light from different branchesMultiwavelength 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 networkData channels: 1548nm, 1551nm1Gb/s 210-1 PRBS NRZL1=8.8km, L2=L3=6.6km, L4 is unmonitoredFBG: 1556.4nm, 1558nm, 1559.7nm3dB passband: 0.4nm, 0.8nm, 0.9nmSawtoothed signal: 2kHz

Summary

Makes use of FBGsNo additional monitoring sourceBoth time and frequency domainWith OTDR techniques, can locate exact fiber cut position

Q&A

Thank you for your attention!