High-Capacity Optical Access Networks

Jacklyn D. Reis, PhD

CPqD, Campinas, São Paulo, Brazil 27-28 May 2013Day 2

High -Capacity Optical Access Networks

© 2005, it - instituto de telecomunicações. Todos os direitos reservados.

Jacklyn D. Reis, PhDAli Shahpari, Ricardo Ferreira, Darlene M. Neves, Mário

Lima, António L. TeixeiraUniversity of Aveiro, Instituto de Telecomunicações

Next Generation PONs

� Internet data traffic has been continuously increasing

� Next generation PONs have been investigated to– support several users with bit rates of 1 to 100 Gb/s– flexible, extended reach and reduced cost

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Source: Cisco, 2012

27-28 May 2013, Campinas, Brazil

Tb/s, 100 km, 1000 users

R. Yadav, "Passive-Optical-Network- (PON-) Based Converged Access Network [Invited]," J. Opt. Commun. Netw. 4(11), B124-B130 (2012). http://www.opticsinfobase.org/figure.cfm?uri=jocn-4-11-B124-g004

Outline

1. Future Optical Access Networks: Coherent WDM-PON – architectures– transceiver configuration– fiber impairments

2. Convergence Scenarios

I. UDWDM

III. Nyquist

II. Convergence

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2. Convergence Scenarios– WDM and XG-PON, G-PON, TWDM or Video

3. High-Capacity PON– Nyquist shaped WDM-PON under different capacities


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FUTURE OPTICAL ACCESS NETWORKS

PART I


Ultra-Dense WDM based Passive Optical Networks

� Goal� up to 1000 users at 1Gb/s (up/down) in a single ODN

� Allocate 1000 users efficiently?� Narrow channel spacing; coherent detection; advanced modulation

formats;� Benefits

� High wavelength selective� High receiver sensitivity� Simple users’ data rate upgrade� DSP eases implementation of equalizers / FEC

I. UDWDM

III. Nyquist

II. Convergence

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� DSP eases implementation of equalizers / FEC� Challenges

� Architecture� Transceiver configuration� Fiber effects


UDWDM: Architectures

�Fully transparent: Splitter– Homogeneous network: coherent channels only– Heterogeneous network: coherent + IMDD channels

�Hybrid: AWG + splitter�Filtered: AWG

I. UDWDM

III. Nyquist

II. Convergence

6 27-28 May 2013, Campinas, Brazil

� Homogeneous ODN � only one technology;� Heterogeneous ODN � convergence scenarios;� CW laser source modulated via an optical IQ modulator fed with

random symbols;� Transmission through Standard Single-Mode Fiber;� 1:N Transparent Power Splitter� ONU: Direct Detection or Coherent Rx

UDWDM: Transceiver Configurations

I. UDWDM

III. Nyquist

II. Convergence

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� ONU: Direct Detection or Coherent Rx


UDWDM: Fiber Impairments

�Fully transparent UDWDM-PON (3.125 GHz grid): Splittera) Homogeneous network: coherent channels onlyb) Heterogeneous network: coherent + legacy (NRZ or Video)

I. UDWDM

III. Nyquist

II. Convergence


32x625 Mbaud @ 3.125 GHz

�Volterra Series to estimate FWM / XPM in coherent UDWDM-PON�MPSK: SPM/XPM negligible; FWM is dominant�MQAM: FWM and XPM are dominant;

FWM

I. UDWDM

III. Nyquist

II. Convergence

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J.D. Reis et al JLT’2012(30), 234-241


FWM+XPM

Different Channel Count

� QPSK� minimal variation with distance� FWM increases up to 32 channels� support 1000 users limited to ~5 Gb/s

� 16/256QAM� higher dependence on distance� XPM increases further than 32 channels� support ~10-25 Gb/s per user limited to ~64 users

I. UDWDM

III. Nyquist

II. Convergence


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CONVERGENCE SCENARIOSPART II


Coexistence with XG -PON / RF Video Overlay

�Fully transparent UDWDM-PON (3.125 GHz grid): Splittera) Homogeneous network: coherent channels onlyb) Heterogeneous network: coherent + legacy (NRZ or Vi deo)

I. UDWDM

III. Nyquist

II. Convergence


UDWMD-PON + Legacy PONs

�16x1.25 Gb/s-QPSK spaced by 3.125 GHz plus 10 Gb/s NRZ or RF Video

I. UDWDM

III. Nyquist

II. Convergence


UDWDM Comb

OSA

10G NRZ

Fiber

Coherent Rx

DSP

IMDD Rx

Video

Coexistence with XG -PON� SSF simulations accurate up to 16.5 dBm

� 10G-NRZ Power≤10 dBm� FWM between QPSK (-3 dBm/ch)

� 10G-NRZ Power>10 dBm� XTalk due NRZ (XPM and possibly FWM)� EVM2 or 1/SNR�P2 (2 dB higher every 1 dB of power)

I. UDWDM

III. Nyquist

II. Convergence


Coexistence with XG -PON

�Fixed 10G-NRZ Power (15 dBm) with variable guard band

�Nonlinear Xtalk decreases for GB≥1.6 nm (~200 GHz)

I. UDWDM

III. Nyquist

II. Convergence


Coexistence with Video overlay

� Video Power≤10 dBm� FWM between QPSK (-3 dBm/ch)

� Video Power>10 dBm� XTalk due Video (XPM and possibly FWM)� EVM2 or 1/SNR�P2 (2 dB higher every 1 dB of power)

I. UDWDM

III. Nyquist

II. Convergence


Coexistence with Video overlay

�Fixed Video Power (16.5 dBm) with variable guard band

�Nonlinear Xtalk decreases for GB>2 nm (~250 GHz)

I. UDWDM

III. Nyquist

II. Convergence


Does UDWDM impact on the other technologies?

�IMDD based*

I. UDWDM

III. Nyquist

II. Convergence

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�RF Video**

*GLOBECOM’11, **OFC’13


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HIGH-CAPACITY PONPART III


“Terabit+ (192 ××××10 Gb/s) Nyquist Shaped UDWDM Coherent PON with Upstream and Downstream over a 12.8 nm Band”, OFC’13, PDP5B3

�Previous work�N. Cvijetic et al “1.92Tb/s coherent DWDM-

OFDMA-PON with no high-speed ONU-side electronics over 100km SSMF and 1:64 passive split”, Optics Express, 19(24), 2011.

I. UDWDM

III. Nyquist

II. Convergence

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passive split”, Optics Express, 19(24), 2011.�48 Gb/s per wavelength � ~16 nm (2 THz)

�In this work�80 Gb/s – 120 Gb/s per channel group � ~13

nm (1.6 THz)�Nyquist shaped UDWDM over DWDM


I. UDWDM

III. Nyquist

II. ConvergenceHow to go further in density keep the ODN budget?

� Spectral efficiency � ~3 GHz optical band / user

� Mitigation of back-reflections� OM2A6 – “Spectral Shaping for Mitigating Backreflections in a Bidirectional 10

Gbit/s Coherent WDM-PON” by D. Lavery; M. Paskov; S.J. Savory

� Mitigation of FWM2BB

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……


2BB

Mitigation of Back-Reflections

�8x10G down + 8x10G up configuration (6.25 GHz): interleaved by 3.125 GHz

I. UDWDM

III. Nyquist

II. Convergence


Mitigation of FWM

�16 16QAM channels at 3.125 GHz

I. UDWDM

III. Nyquist

II. Convergence


Outline

� Coherent UDWDM-PON setup

� Nyquist shaped optical spectra

I. UDWDM

III. Nyquist

II. Convergence

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� Experimental results� 5 Gb/s per channel or user� 10 Gb/s per channel or user

� Conclusions


Experimental setup

�Bi-directional Nyquist Shaped 16QAM UDWDM over DWDM (100 GHz)

I. UDWDM

III. Nyquist

II. Convergence


UDWDM Comb

OSA

Fiber

Coherent Rx

DSP

AWG DRTO

DWDM

Upstream

MZM

Optical Spectra: UDWDM Nyquist Shaped

� 12x10 Gb/s at 5 GHz� 14x10 Gb/s at 3.125 GHz� 16x5 Gb/s at 2.5 GHz

I. UDWDM

III. Nyquist

II. Convergence


EVM: 5 Gb/s per channel� Sensitivity�-35 dBm (single), -30 dBm (UDWDM)� Optimum power 40 km� -10 dBm (1 UDWDM), -15

dBm (16 UDWDM)

I. UDWDM

III. Nyquist

II. Convergence


EVM: 5 Gb/s per channel

�EVM per channel at optimum power for the 1550 nm UDWDM channel group

I. UDWDM

III. Nyquist

II. Convergence


BER: 5 Gb/s per channel

�Power margin around 10 dB

I. UDWDM

III. Nyquist

II. Convergence



� Sensitivity�-32 dBm (single), -27 dBm (UDWDM)� Optimum power 40 km� -11 dBm (1 UDWDM), -14

dBm (16 UDWDM)

I. UDWDM

III. Nyquist

II. Convergence



�EVM per channel at optimum power for the 1550 nm UDWDM channel group

I. UDWDM

III. Nyquist

II. Convergence


BER: 10 Gb/s per channel

I. UDWDM

III. Nyquist

II. Convergence


Conclusions

�Coherent detection plays an important role on Future Optical Access Networks

�Coherent Optical solutions better exploit the full capacity of OANs� Convergence

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� Convergence� Simple bandwidth upgrade�Optical filter-free ONUs� T/Rx Sensitivity� symmetric and dedicated bandwidth

�Performance optimization� Advanced modulations� Digital Signal Processing� Advanced filtering


Acknowledgements

�Funding

�NG-PON2: ADI 30370

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�Collaborators


Implementation of Nyquist Shaping

�Implementation– 4096 16QAM random symbols � 16392 bits (Gray Coding)– 10 GSa/s 1.25 Gbaud (8 Samples per symbol, 32784 samples)– 10 GSa/s 2.5 Gbaud (4 Samples per symbol, 16392 samples)– Roll-off factor � 0– Pre-emphasis filter: 1st Gaussian ~3 GHz


Technology

High-Capacity Optical Access Networks