ultra-dense, transparent and resilient ring-tree access network using coupler-based remote nodes and...

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Universitat Politècnica de Catalunya (UPC)Dept. of Signal Theory and Communications (TSC)

Optical Communications Group (GCO)www.tsc.upc.edu/gco

Univ

ers

itat

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cnic

ade C

ata

lunya

UltraUltra--Dense, Transparent and Resilient Dense, Transparent and Resilient

RingRing--Tree Access Network using Tree Access Network using

CouplerCoupler--based Remote Nodes and based Remote Nodes and

Homodyne TransceiversHomodyne Transceivers

Josep M. Fabrega and Josep Pratjprat@tsc.upc.edu

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OpticalOpticalOpticalOptical accessaccessaccessaccess evolutionevolutionevolutionevolution

TIMECATV

ADSL

FTTH-PtP

FTTHG/E-PON

FTTHWDM-PON

POTs

FTTH

WDM&TDM-PON

COST

xDSL

TIME

CAPACITY

FTTH ultra-dense WDM-PON

ngPON

WDM - PONWDM - PON

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WDM

TIME

TDM

� Few wavelengths

� High-speed

∙ Rb>>BWu

∙ Power consumption

� 1000 wavelengts

� Low-speed

∙ Rb = BWu

∙ Lambda-to-the-user

IntroductionIntroductionIntroductionIntroduction

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IntroductionIntroductionIntroductionIntroduction

� Migration from TDM/WDM to pure WDM

� Ultra-dense WDM PONs

∙ Multiple low capacity channels

� E.g. 1 Gbps

λ

More than 1500 ch. at C band

...........................

3 GHzOL

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IntroductionIntroductionIntroductionIntroduction

∙ IM-DD systems limited by:

� Sensitivity

�Optical filters selectivity

∙ Coherent systems

�Heterodyne

– Image frequency problems

�Homodyne

– oPLL (phase lock problems)

– IQ, Feed-Forward, Phase Diversity

LocalLaser

+

-

+

-OpticalInput Ip(t)

λ

...........................

3 GHzλLO

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IntroductionIntroductionIntroductionIntroduction

Locallaser

+

-

Data and Phase

recovery

IM or PM

Data

DataReceiver

TransceiverDPSK Downstream

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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

� Phase diversity achieved by switching local laser phase

� 3 dB penalty with respect to an ideal homodyne system due to the phase switching

� Several schemes proposed

I Q

t0 t0+T/2 t0+Tt

I Q

t0+3T/2 t0+2T

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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

Laser

CLKRecovery

+

-

PhaseScrambler

Tb

Tb

Tb/2

Data out

OpticalInput

I’

Q’

Vout

+

I’

Q’

outV

[1] J. Prat and J. M. Fabrega, ECOC 2005, Glasgow, Scotland, sept. 2005, paper We.P.104

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90º

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UPC Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase & & & & PolarizationPolarizationPolarizationPolarization

DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

Laser

CLKRecovery

+-

PhaseScrambler

Tb

Tb

3Tb/2

Data out

OpticalInput

Pol. Scrambler

freq. doubler

Tb

Tb/2

Tb

Tb/4

0º

90º

H

V

[3] J. M. Fabrega and J. Prat, OFC 2006, Anaheim CA, March 2007, paper JThB45

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Time Time Time Time SwitchingSwitchingSwitchingSwitching PhasePhasePhasePhase DiversityDiversityDiversityDiversity ReceiverReceiverReceiverReceiver

Laser

CLKRecovery

+

-

PhaseScrambler

Tb

Data out

ES(t)

Tb/2ELO(t)

IP(t) I f(t)

Transmission experiments (1Gbps) [2]:• -38 dBm sensitivity @ BER 10-9

• 18 MHz linewidth tolerance @ BER 10-3

• 100 MHz detuning tolerance• WDM Channel spacing of 3 GHz @ 1 dB Penalty BER 10-9

[2] J. M. Fabrega and J. Prat, OSA Optics Letters, vol. 32, no. 5, pp. 463-465, March 2007

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Network Network Network Network topologytopologytopologytopology and and and and wavelengthwavelengthwavelengthwavelength planplanplanplan

x/y coupler x/y coupler

50/50 couplerRNn

λ

C band

..................

4 GHz

CO

CPE

RN2

RNnWest

East

RN11:K powersplitter

CPECPE

CPE

CPECPE

CPE

2 splittersper RN

� Ring+trees PON (SARDANA-like)

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Central Office Central Office Central Office Central Office schemeschemeschemescheme

� DFB lasers + splitters + switches + EDFA

� Double fiber architecture

∙ No Rayleigh Backscattering

WestCO

EastTx/Rx

Optical switch

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WDM WDM WDM WDM treetreetreetree PON experimentsPON experimentsPON experimentsPON experiments

� Transmission experiments at 1 Gbps

� DPSK modulation format

� CO output power: 0 dBm

� Losses

∙ 30 km fiber spool � 5.2 dB

∙ 4 Remote nodes

� 1.6 dB for pass-through

� 13.2 dB for drop

∙ Second distribution stage

� Emulated by means of a VOA

� 21 dB losses to the link � 1:128 splitting ratio

� Overall splitting ratio: 4x2x128=1024 homes

-60

-50

-40

-30

-20

-10

0

0 500 1000 1500 2000

Frequency (MHz)

Po

wer

(d

Bm

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Experimental Experimental Experimental Experimental resultsresultsresultsresults

-12

-10

-8

-6

-4

-2

0

-52 -50 -48 -46 -44 -42 -40 -38Pin (dBm)

log(

BE

R)

RN1RN2RN4

40.1 dB41.5 dB40.7 dB-44.2 dBm41.2 dB42.9 dBPowerBudget

39.4 dB41 dB44.2 dB44.2 dB41 dB39.4 dBLink Losses

-40-2 dBm-41.6 dBm-40.8 dBm-44.3 dBm*-41.3 dBm-43 dBmSensitivity

RN4RN2RN1RN4RN2RN1

Resilient modeNormal Operation10-9 (*10-6 )

� BER floor due to phase noise and mixer electronics.

� FEC required for resilience

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ConclusionsConclusionsConclusionsConclusions

� A combined ring-tree access network topology has been demonstrated∙ Flexible, scalable

∙ large number of users (up to 1024102410241024)

∙ Large capacity (more than 1 Tb/s)

∙ completely passive outside plant

∙ wavelength-transparent remote nodes � GPON ODN compatible

� Transmission experiments at 1 Gb/s∙ sensitivity of -43 dBm in RN1, after 30 km

∙ Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10Power budget of 42.9 dB (49 dB at 10----3333))))

∙ 4 GHz channel spacing4 GHz channel spacing4 GHz channel spacing4 GHz channel spacing

∙ FEC is convenient for robutsness.

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AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgements

� Dr.-Ing. Ronald Freund (HHI) � Dr. Carlos Bock (UEssex)

ThanksThanks!!!!jprat@tsc.upc.edu

www.tsc.upc.edu/gco