Flexible optical networking with spectral or spatial super-channels

1“Networks and Optical Communications” research group – NOC

Flexible optical networking with spectral or spatial super-channels

Presented by: Dr. Ioannis Tomkos ([email protected])

Co-Authors: P. S. Khodashenas, J.M. Rivas-Moscoso, D. Klonidis, D. M. Marom, G. Thouénon, A. Ellis, D. Hillerkuss, J. Zhao, D. Siracusa, F. Jiménez, N. Psaila

IV International Workshop on trends in optical technologiesCampinas, Sao Paulo, Brazil – May 27th & 28th 2015

2

AIT’s role in the optical network evolution

Scope: Research on architectures, protocols, algorithms, transmission systems and technologies for high-speed telecommunication systems applicable in backbone networks, access networks and interconnection of servers (DCNs) and processors (HPC)

Scientific Results (2003-2015): Over 150 publications in archival

scientific journals and magazines (including best paper awards and highly cited papers)

Over 400 publications in major international conferences and workshops

Participated in over 25 research projects: 5 projects within FP6 and 12 projects within FP7 and 1 H2020

Led 8 EU research projects as Technical Manager of the entire consortium: 2 FP6 and 6 FP7

3

FOX-C & INSPACE goals & status

4

Presentation overview

Evolution of Optical Communication Systems & Networks

Spectrally flexible optical networking• The activities of EU project FOX-C

® Spectrally flexible super-channel transceivers® Nodes for all-optical add/drop of sub-channels® Networking studies to demonstrate the benefits of FOX-C solution

Spatially flexible optical networking• The activities of EU project INSPACE

® Nodes for independent or joint switching of SDM super-channels® Networking studies to demonstrate the benefits of INSPACE solution® Development of an SDN-based control plane for SDM-based networks

Summary & Conclusions

5

Historical evolution of optical communications system capacity and bit-rate distance product

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1983 1987 1991 1995 1999 2003 2007 2011 2015

Tota

l Fib

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ity

(Tb

it/s

)

Bit

Rat

e D

ista

nce

Pro

du

ct

(Gb

it/s

.Mm

)

Year Published

WDM

TDM

OFDM/CoWDM

Coherent Detection

Spatial Multiplexing

Total capacity

• Traffic increases at a rate of 20-40% per year, while capacity of deployed SMF-based networks approaches fundamental limits…

• New traffic characteristics lead to new network requirements:• Rapidly changing traffic patterns• High peak-to-average traffic ratio• Ultra-large data-chunks transfers• Asymmetric traffic between nodes • Increasing high-QoS traffic

• Fiber bandwidth was consider for many years as an abundant resource, but we have almost utilized to the maximum extend the EDFA amplifiers bandwidth (i.e. while approaching the fundamental SE limits)• A short-term solution is to utilize the available fiber spectrum more efficiently/wisely as is

the case in wireless networks where bandwidth was always a limited/scarce resource - (Spectrally flexible systems/networks)

• A forward-looking option is to deploy new fibers (or use strands of available SMF fibers) that can support multi-cores or/and multi-modes per core (SDM/Spatially-flexible systems/ networks)

Data from Prof. Andrew Ellis

6

Spectrally flexible optical networking

The activities of EU project FOX-C

7

Main building blocks to enable spectrally flexible optical networking

Flexible Optical Networking

Flexible transponders

Strong research field over last 5 years

Network planning and control plane

issuesNetworking

studies have proved the benefits of flexible

networking

Flexible switching nodes

Limited number of demos showing mostly “drop”

function

Ioannis Tomkos et. al., “A Tutorial on the Flexible Optical Networking Paradigm: State-of-the-Art, Trends, and Research Challenges”, Invited paper at the “Proceedings of the IEEE” (Impact Factor: 6.91) 05/2014

8

Super-channels when combined with mini/flexi-grid offer spectrum savings!

Super-channels can enable a path to higher bit-rates and support flexible optical networking

9

How to add/drop sub-channels out of super-channels in a three-level spectrally flexible optical node?

Level 3 Express through or add/drop of Tb super-channels (via conventional WSSs) Level 2 Processing (add/drop/erase) of super-channel contents

• Offers grooming capabilities in the optical domain! – How to do it? Level 1 Generation/Detection and regeneration of sub-channel contents

• Electronic processing

10

The FOX-C project consortium

Optronics Technologies S.A• Mr. George Papastergiou (Coordinator)• Dr. Marianna Angelou• Dr. Thanasis Theocharidis

Finisar Israel LTD • Dr. Shalva Ben-Ezra

W-Onesys S.L. • Dr. Jordi Ferré Ferran (WP6 Leader)

Orange Labs – FT• Dr. Erwan Pincemin (WP5 Leader)• Dr. Christophe Betoule• Dr. Gilles Thouenon

Athens Information Technology

The Hebrew University of Jerusalem

Eidgenössische Technische Hochschule Zürich

University College Cork

Aston University

• Dr. Ioannis Tomkos (Technical Mngr)• Dr. Dimitrios Klonidis (WP2 Leader)• Dr. Pouria S. Khodashenas• Dr. José M. Rivas-Moscoso • Prof. Dan Marom (WP4 Leader) • Prof. Juerg Leuthold• Dr. David Hillerkuss (WP3 Leader)• Mr. Benedikt Bäuerle • Dr. Jian Zhao • Prof. Andrew Ellis• Dr. Stylianos Sygletos• Dr. Simon Fabbri• Dr. Andreas Perentos

11

Spectral super-channel multiplexing schemes in FOX-C

QAM qN-WDM super-channels

Conventional WDMe(f)OFDM MB-e(f)OFDM

AO-OFDMNFDM qN-WDM super-channels

(q)N-WDM

12

FOX-C system test-bed

Testbed assembled at FT/Orange Labs premises:

13

Experimental characterisation of flexible transceivers

BER vs SNR

ROF: Roll-off factor

NWDM e-fOFDM

Nyquist FDM MB-eOFDM

14

The FOX-C node architecture for N-WDM super-channels

Enables all-optical add/drop of sub-channels out of non-spectrally-overlapping (q)N-WDM super-channels

15

FOX-C’s novel ultra-fine spectral resolution filters

Based on a state-of-the-art phased array implemented with a high resolution AWG

Achieved record resolution and addressability values• Record resolution: <1GHz • Record addressability (spectral granularity): 200MHz

* Roy Rudnick, et. al., “One GHz Resolution Arrayed Waveguide Grating Filter with LCoS Phase Compensation”, in proc. OFC/NFOEC 2014, paper Th3F.7

16

The EU project FOX-C node architecturefor AO-OFDM super-channels

Enables all-optical add/drop of sub-channels out of spectrally-overlapping OFDM super-channels

17

Novel all optical ROADM for OFDM signals

* S. Sygletos et al., “A Novel Architecture for All-Optical Add-Drop Multiplexing of OFDM Signals”, in proc. ECOC 2014, Sept. 2014.

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Results demonstrate that, in the case of qN-WDM, there is negligible reach penalty when the FOX-C nodes are considered along the signal path

Transmission studies with cascaded FOADMs

N-WDM qN-WDM

f = 25 GHz f = 25.9 GHz f = 26.8 GHz

19

Nyquist WDM super-channel composed of Nyquist-shaped sub-channels: Do we need “Gridless”?

12.5GHz

187.5 GHz

200 GHz

134 GHz

150 GHz

(*) P. Sayyad Khodashenas et al., “Evaluating the Optimum Filter Resolution and Sub-Channel Spectrum Granularity for Flexible Super-Channels”, OFC 2015, paper W1I.5.

Sub-band allocation options according to frequency slot width• ITU-T 12.5 GHz grid

• Gridless

The super-channel bandwidth depends on the chosen sub-channel granularity. Two examples are shown above:

Super-channels allocated on ITU-T 12.5 GHz grid (including GB = 12.5GHz). “Gridless” operation – Does it offers significant advantages?

* P. S. Khodashenas, J. M. Rivas-Moscoso, D. Klonidis, D. M. Marom and I. Tomkos, “Evaluating the Optimum Filter Resolution and Sub-Channel Spectrum Granularity for Flexible Super-Channels”, in proc. OFC/NFOEC 2015, paper W1I.5.

20

Networking studies to derive specifications

Optimized sub-channel slot size from a network-level perspective:• Flex-grid qN-WDM systems with frequency-slot size of 12.5 GHz and coarse

switching in GÉANT2 pan-EU network topology. • Optimum sub-channel grid was investigated:

Best compromise

* P. S. Khodashenas, J. M. Rivas-Moscoso, D. Klonidis, D. M. Marom and I. Tomkos, “Evaluating the Optimum Filter Resolution and Sub-Channel Spectrum Granularity for Flexible Super-Channels”, in proc. OFC/NFOEC 2015, paper W1I.5.

21

Techno-economic studies – FOX-C vs legacy solutions

Is the FOX-C solution worth considering for real deployments? • Are the resulting network-wide capital expenditure savings significant enough

to justify a FOX-C-like solution?

• Inputs for the analysis: ® Network topology, traffic matrix (FT/Orange national network) ® Cost model * ® It requires also a novel routing, modulation level and spectrum allocation algorithm that

matches the FOX-C networks solution characteristics (AOTG-RMLSA) **• Outputs from the analysis:

® Utilized resources (such as transceivers, nodes and spectrum) to guarantee blocking-free connection establishment, while minimizing the spectral occupancy.

– Benchmarks:» SLR over fixed-grid (widely deployed network solution)» MLR over flexi-grid (common understanding of flexible optical networks)

* Ref: J. Rivas-Moscoso, S. Ben-Ezra, P. Khodashenas, D. Marom, D. Klonidis, P. Zakynthinos & I. Tomkos “Cost & Power Consumption Model for Super-channel Transmission with All-Optical Sub-channel Add/Drop Capability” ,(Invited) ICTON 2015.

** Ref: P. S. Khodashenas, J. M. Rivas-Moscoso, D. Klonidis, G. Thouénon, C. Betoule and I. Tomkos, “ Impairment-aware Resource Allocation over Flexi-grid Network with All-Optical Add/Drop Capability”, submitted to ECOC 2015.

22

FOX-C cost & power consumption model

Cost and power consumption model:

• Benchmark: Single carrier 100G transceiver

• Tb/s super-channel transceiver based on:® Electrical multiplexing schemes:

– NFDM, NWDM with electrical filtering, MB-e(f)OFDM® Optical multiplexing schemes:

– (q)NWDM with optical filtering– Conventional AO-OFDM with DSP

• ROADM implementations:® Supporting non-overlapping sub-channel A/D® Supporting overlapping and non-overlapping sub-channel A/D

• Sensitivity analysis

J. Rivas-Moscoso, S. Ben-Ezra, P. Khodashenas, D. Marom, D. Klonidis, P. Zakynthinos & I. Tomkos “Cost & Power Consumption Model for Super-channel Transmission with All-Optical Sub-channel Add/Drop Capability” ,(Invited) ICTON 2015.

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Benchmark: 100G transceiver

SLR/MLR 100G transceiver:

DS

P ch

ip

Data in/out

/2

Q I

/2

DP IQ Mod

Q I

DAC

DAC

DAC

DAC

ADC

ADC

ADC

ADC

ECL

LO

Drivers

RF LP filters

RF LP filters (optional)

PBS

PBSSx

Sy

LOy

LOxIx

Qx

Iy

Qy

90º HybridTIA

DP coherent receiver

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Benchmark: 100G transceiver

SLR/MLR transceiver:

(*) Relative to cost of 100G transceiver. (**) Relative to cost of 10G transceiver

SLR/MLR TRx

Component Relative Unit cost (*)

Power (W) [max] # Relative

cost (*)Relative cost (**)

Total power (W)

DSP Chip 0.36 38.5 1 0.36 1.9 38.5

PM IQ Mod 0.22 0.0 1 0.22 1.1 0.0

Laser (Tx & Rx LO) 0.05 1.5 2 0.11 0.3 3.0

4-Port Modulator Driver 0.07 6.0 1 0.07 0.4 6.0

RF LP filter 0.004 0.0 8 0.03 0.0 0.0

DP Coherent Receiver 0.22 1.5 1 0.22 1.1 1.5

1.00 5.2 49.0

Actual cost (not price!) in the range

of 25-30K!!!

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Cost/power comparison of spectrally flexible super-channel transceivers

Cost/power per sub-channel for super-channel transceivers capable of generating different numbers of sub-channels:

(*) Relative to cost of 100G transceiver.

Electrical

multiplexing schemes

NWDM with optical filters

AO-OFDM

Number of sub-

channelsCost (*) P (W) Cost (*) P (W) Cost (*) P (W)

4 0.80 50.8 0.98 52.8 0.79 50.8

6 0.76 49.2 0.84 50.5 0.75 49.2

8 0.74 48.4 0.77 49.4 0.73 48.4

10 0.73 47.9 0.73 48.7 0.72 47.9

12 0.72 47.6 0.71 48.3 0.71 47.6

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Non-overlapping sub-channel A/D capable OXC node

Node with D=3 degrees:W Sch Tx

N R

xS

Rx

N Sch Tx

S Sch TxW Rx

Switches with D-1 switching states

Sbch Tx

Sbch Tx

Drop Add

Sbch T

x

W

S

N

A/D

+22

+10

+22+10

+22+10

-5

-5

-5 -5

-5 -5

+8 +14 -0.5 -0.5-15

-22 dBm/50 GHz -2 dBm/C-band

020

-5 / 15

-5

-10 / 10

0 / 20

0 -15

-10

0

-5

Numbers in black: dB Numbers in green: dBm

A/D

A/D

Number of sub-channel add/drop cards M = 3

A/D card based on HSR filter in R. Rudnick, ECOC 2014, PD.4.1

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Non-overlapping sub-channel A/D capable OXC node

Node with D=3 degrees and M = 3 A/D cards:

(*) Cost relative to 100G transceiver cost(**) Cost relative to 10G transceiver cost(***) Cost relative to cost of an OXC node of degree D without sub-channel A/D capability(^) Due to sharing of management between amplification modules. Factor is applied to number of amplifiers minus

1

F-OXC with degree D and M HSR filters

Component Relative unit cost (*)

Power (W) # Relative

cost (*)Relative cost (**)

Relative cost (***)

Power reduction factor (^)

Total Power (W)

1×20 WSS 0.54 4.00 6 3.24 16.92 0.86 24.0

1x1 HSR filter 0.54 4.00 3 1.62 8.46 0.43 12.0

Variable gain dual-stage amplifier 0.18 12.00 6 1.08 5.64 0.29 0.10 66.0

1x(D-1) switch 0.01 0.00 6 0.09 0.45 0.02 0.0

6.02 31.47 1.59 102.0

Note: A similar investigation was performed for nodes suitable for overlapping sub-channels

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Overlapping sub-channel A/D capable OXC node

Node with D=3 and M=3 for an A/D card implementation based on N gates

F-OXC with degree D and M TIDE filters TIDE with N gates

Component Unit cost (*)

Power (W) # Cost

(*)Cost (**)

Cost (***)

Power reduct. factor

(^)

Total Power

(W)

1×20 WSS 0.54 4.00 6 3.24 16.9 0.9 24.01x1 HSR filter 0.54 4.00 0 0.00 0.0 0.0 0.01xN HSR filter 0.72 4.00 4 2.88 15.0 0.8 16.0Integrated TIDE 0.11 4.00 2 0.22 1.1 0.1 8.0Variable gain amplifier 0.11 9.00 2 0.22 1.1 0.1 0.10 16.2Variable gain dual-stage amplifier 0.18 12.00 5 0.90 4.7 0.2 0.10 55.2

1x(D-1) switch 0.01 0.00 4 0.06 0.3 0.0 0.07.50 39.2 2.0 119.4

(*) Cost relative to 100G transceiver cost(**) Cost relative to 10G transceiver cost(***) Cost relative to cost of an OXC node of degree D without sub-channel A/D capability(^) Due to sharing of management between amplification modules.

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Results of techno-economic studies comparing FOX-C vs SLR/MLR legacy solutions

* P. S. Khodashenas, J. M. Rivas-Moscoso, D. Klonidis, G. Thouénon, C. Betoule, E. Pincemin and I. Tomkos, “Techno-Economic Analysis of Flexi-Grid Networks with All-Optical Add/Drop Capability”, submitted to PS2015.

~15%

~30%

~30%

FOX-C based solutions can offer up to 30% cost savings compared to non-grooming

capable end-to-end solutions using either SLR or MLR

30

Techno-economic studies – FOX-C (all-optical grooming) vs. OTN (electronic grooming ) based solutions - I

* G. Thouénon, C. Betoule, E. Pincemin, P.S. Khodashenas, J.M. Rivas-Moscoso, I. Tomkos, submitted to ECOC 2015.

S0: SLR over fixed-gridS1: Nyquist WDM S2: MB-OFDM

… but can FOX-C based solutions offer significant cost savings compared to conventional OTN based grooming-capable solutions?

(study performed in collaboration with France Telecom/Orange)

31

Techno-economic studies – FOX-C (all-optical grooming) vs. OTN (electronic grooming ) based solutions - II

+37% +36%

+60%

-29%

(a) For Traffic Volume V1+23%

+10%-21%-18%

(b) For Traffic Volume V2

V1: 7 Tbps of ingress trafficV2: traffic increase projection spanning roughly eight years with a constant per-year traffic growth of 35%

Global multi-layer transport network cost comparison

32

Spatially (and spectrally) flexible optical networking

The activities of EU project INSPACE

33

What’s next in capacity expansion… In Space

Space is the obvious yet unexplored (until 2009) dimension• …BUT by simply increasing the number of systems, the cost and power consumption also

increase linearly!

Efficient use of the space-domain requires “spatial integration of elements”* • Significant efforts in the development of FMF and MCF (fibre integration)• Multi-link amplification systems have also be proposed and developed• Tx/Rx integration is a hot and very active topic

• Optical switches are largely unexplored so far (INSPACE focus!)

MC/FM EDFA/EDFA array

MCF/FMF/Bundle of SMF

Tx PIC Rx PIC

* Peter J. Winzer, “Spatial Multiplexing: The next frontier in network capacity scaling”, Tutorial paper at ECOC 2013

34

Degrees of freedom in SDM transmission/switching are defined by the type of transmission medium and how crosstalk is handled

Core count Mode count Cladding diameter Core layout

• Geometry• Homo-/heterogeneous core

structure

Refractive-index profile• Graded-index• Step-index• Trench-assisted

Be c

aref

ul w

ith:

dBUFFER=250m

dCLADDING=125m

dCORE=8m

SMF

Inter-core crosstalk Inter-mode crosstalk Differential mode group

delay (DMGD) Bend loss Nonlinearity Process variability

35

Degrees of freedom in SDM transmission



structure



delay (DMGD) Bend loss Nonlinearity Process variabilityBe

car

eful

with

:

dBUFFER=250m

dCLADDING=125m

dCORE=8m

SMF

36




structure




car

eful

with

:

Bundle of SMF

(A) Uncoupled spatial modes

37




structure




car

eful

with

:

Bundle of SMFMCF

(A) Uncoupled spatial modes

38




structure




car

eful

with

:

MCF

(A) Uncoupled spatial modes(B) Coupled spatial modes

39




structure




car

eful

with

:

MCF

40




structure




car

eful

with

:

FM-MCF

LP01

LP11

LP21

LP02

(C) Coupled spatial subgroups

41

Hero transmission experiments based on SDM

… BUT all these are very good for the spatial capacity increase in Point-to-Point systems…

…WHAT ABOUT using the spatial dimension for optical networking

42

Evolution from spectrum flexible to spatially (& spectrum) flexible optical networking

Spectrum based BW allocation

Spatial & Spectrum based BW allocation

Spectrum Flexible Optical Networking- Combined selection of channel bandwidth (format/ data rate) and spectral allocation according to: demand, distance and required performance- λ + format/rate tunable TxRx- Flexible switching of variable spectral slots at different wavelengths- Optimized spectral usage

Spatially and Spectrally Flexible Optical Networking

- Extend flexibility to the space switching domain- Multi-dimensional switching granularity - Channel allocation over a. multiple Modes/Cores/fibres b. multiple spectral slots- Optimized system bandwidth usage - Combined spectral – spatial optimization.- Multi-dimensional flexible switching

43

The INSPACE project consortium

Optronics Technologies S.A• Mr. George Papastergiou (Coordinator)• Dr. Nina Christodoulia • Dr. Thanasis Theocharidis

Telefónica Investigación y Desarrollo SA

•Mr. Felipe Jiménez-Arribas (WP2 Leader)•Dr. Víctor López•Dr. Óscar González de Dios

The Hebrew University of Jerusalem • Prof. Dan Marom (WP4 Leader)• Dr. Miri Blau

Athens Information Technology• Dr. Ioannis Tomkos (Technical

Mngr)• Dr. Dimitrios Klonidis (WP6 Leader)• Dr. Pouria S. Khodashenas• Dr. José M. Rivas-Moscoso Optoscribe Ltd.

CREATE-NET (Center for Research and Telecommunication Experimentation for Networked Communities)

Aston University

Finisar Israel Ltd.

W-ONE SYS SL

• Dr. Nicholas Psaila• Dr. John MacDonald• Dr. Paul Mitchell • Dr. Domenico Siracusa (WP5 Leader)• Dr. Federico Pederzolli• Dr. Elio Salvadori• Prof. Andrew Ellis (WP3 Leader)• Dr. Stylianos Sygletos• Dr. Naoise Mac Suibhne• Dr. Filipe Ferreira• Dr. Christian Sánchez-Costa • Dr. Shalva Ben-Ezra • Dr. Jordi Ferré Ferran (WP7 Leader)• Dr. Jaume Mariné

44

INSPACE project channel allocation concept

Modes/Cores

Wavelengths

Data rate(Modulation level)

Degrees of Flexibility

Modesor

Cores

f

f

f

f

f

• Channels with flexible capacity can be allocated over:– one or few modes/multi cores – occupying a single or multiple spectral slots

: end-to-end allocated channel

“Spatial expansion of the spectrum over multiple modes/cores and therefore definition of a superchannel over two dimensions (instead of the spectrum only dimension)”

SMF-Bundle

or

FMFor

MCF

Frequency Frequency

Conventional optical OFDM Optical fast OFDM

(N-1)/T

(N-1)/2T

N is the channel number (=7 in this example)

(a) (b)

Frequency Frequency

Conventional optical OFDM Optical fast OFDM

(N-1)/T

(N-1)/2T

N is the channel number (=7 in this example)

(a) (b)N-WDMor

OFDMorSC-M-QAM

Fibre, Mode,Core

45

SDM switching classification

Independent spatial/spectral channel switching Spectral channel switching

Spatial channel switching Spectral channel switching of spatial subgroups

* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)

46




(A)

R&S node design for independent spatial/spectral channel switching


47



Spatial channel switching Spectral channel switching of spatial subgroupsR&S node design for spectral channel switching across all spatial modes

(A)

R&S node design for independent spatial/spectral channel switching


48



Spatial channel switching Spectral channel switching of spatial subgroupsR&S node design for spectral channel switching across all spatial modes

(C)

OXC design for spatial channel switching across all spectral channels


49* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)




(C)

OXC design for spatial channel switching across all spectral channels

(D)

R&S node design for hybrid fractional space-full spectrum switching granularity

50

Comparison of SDM switching options

Space-wavelength granularity Space granularity Wavelength granularityFractional space-full

wavelength granularity

Minimum switching granularity

Bandwidth of a single WDM channel present at a single spatial mode.

Bandwidth of entire optical communication band carried on a single spatial mode.

Bandwidth of a single WDM channel spanning over all spatial modes.

Bandwidth of a single WDM channel over a subset of spatial modes.

Realization

With OXC: High-port count OXC and at least 2M conventional WSS per I/O fiber link. Without OXC: 2M conventional WSS per I/O fiber link. 4M if WSS placed on add/drop.

Moderate port count OXC, and 2 WSS per mode selected for WDM channel add/drop.

4 joint switching WSS per I/O fiber link in route-and-select topology applied to all spatial modes in parallel.

4×M/P joint switching WSS modules per I/O fiber link.

Flexibility

With OXC: Each mode/WDM channel independent provisioned and routed. Supports SDM lane change. Single point of failure.Without OXC: Each mode/WDM channel independently provisioned and routed. Spatial mode maintained. Prone to wavelength contention.

The complete optical communication band is routed across network. Coarse granularity. If WDM channels need to be extracted from many modes then WSS count quickly escalates.

Each spatial super-channel provisioned across all modes. Susceptible to wavelength contention. Add/drop bound to direction.

Compromise solution using small SDM groups. More efficient when provisioning low capacity demands.

Scaling

With OXC: Can quickly escalate to very large port counts. Switching node cost linearly scales with capacity, no price benefit to SDM.

Conventional OXC can support foreseeable mode and fiber counts. OXC is single point of failure. Pricing favorable but with greater add/drop require more WSS modules.

Cost roughly independent of SDM count. Inefficient for low capacity connections due to minimum BW provisioned across SDM. Large SDM Rx/Tx are integration and DSP challenge.

Cost scales as group count. Groups can be turned on as capacity grows, offering pay-as-you-go alternative. Maintaining small group sizes facilitates MIMO processing at Rx.

Estimated loss

With OXC: 13 dB per I/O fiber link. Without OXC: 10 dB per I/O fiber linkFor MCF or FMF transmission fiber, extra 4 dB loss is induced by the spatial MUX/DEMUX

3 dB per I/O fiber link being switched. If add/drop from SDM fiber is extracted, 10 dB excess loss for through.For MCF or FMF transmission fiber, extra 4 dB loss is induced by the spatial MUX/DEMUX

10 dB per I/O fiber link.For MCF or FMF transmission fiber, extra 4 dB loss is induced by the spatial MUX/DEMUX

10 dB per I/O fiber link.For MCF or FMF transmission fiber, extra 4 dB loss is induced by the spatial MUX/DEMUX

51

SDM technology elements

INSPACE SDM Wavelength Selective Switch• High port count WSS for joint switching of spatial modes

A conventional 120 WSS can turn into a 7-mode(12) spatial-spectral WSS. First demonstration in OFC 2012

New port definition: S(MN)

S = nº of spatial modes

In1

Out1

Out2 M = nº of input fibre subgroupsN = nº of output fibre subgroups

52


A conventional 120 WSS turns into a 7-mode(12) spatial-spectral WSS. First demonstration in OFC 2012

New port definition: S(MN)

INSPACE SDM Wavelength Selective Switch• High port count WSS for joint switching of spatial modes

®By adding a 2-D SMF array, a higher port count can be achieved

®With a fibre array of 316 (functional) fibres, a 3-mode(115) spatial spectral high port count WSS has been designed/fabricated

S modes per input/output

M = 1 input

N outputs

2-D Fibre array

53


INSPACE Mode MUX/DEMUX• MCF breakout designed and fabricated for MCF

• FMF photonic lantern designed and fabricated®Fabrication optimisation yielded

low IL (2 dB) with a loss uniformity of 0.8 dB

54


INSPACE Mode MUX/DEMUX• MCF breakout designed and fabricated for MCF

• FMF photonic lantern designed and fabricated®Fabrication optimisation yielded

low IL (2 dB) with a loss uniformity of 0.8 dB

The performance of the photonic lantern is better than competing commercial devices and fully packaged devices are ready to be deployed. These will be launched as an improved product at ECOC in Sept. 2015.

55

Comparison of spectral and spatial super-channel allocation policies for SDM network operation, taking into account the spectral efficiency/reach trade-off

First study carried out for SDM networks based on SMF bundles

For such an SDM system, the focus is on the comparison between two extreme allocation strategies:• Parallel systems with spectral super-channels (SpeF)• Parallel systems with spatial super-channels (SpaF)

SDM resource allocation issues

• MCFs and FMFs with coupled transmission cores/modes present special challenges in terms of their physical layer performance and implementation complexity

56

SDM allocation options: • A: SpeF – Spectral super-channels with flexi-grid

• B: SpaF – Spatial super-channels with fixed spectral width

SDM allocation options considered

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Super-channel allocation options: • A: Over spectrum (SpeF)• B: Over space (SpaF)

Resource allocation options and trade-offs

Big enough spacing to neglect the crosstalk between adjacent super-channels* The GB size is the same for both cases

No crosstalkamong cores

Crosstalk between adjacent sub-channels leads to

optical reach reduction

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Blocking results (under independent switching)

1.E-4

1.E-3

1.E-2

1.E-1

300 600 900 1200 1500

BP

Input Load [Erlang]

SpeF-Var

SpeF-34.375

SpeF-37.5

SpeF-WDM

SpaF-WDM

BP vs input load to the network for several SpeF and SpaF allocation options (simulations performed for Telefónica’s Spain national network):

(a) SpeF-Var: SpeF using variable spacing adapted to the path length

(b) SpeF-34.375, SpeF-37.5, SpeF-50: SpeF using fixed spacing (34.375, 37.5 GHz and 50 GHz) with 12.5-GHz GB on both sides of each Sp-Ch

(c) SpeF-WDM and SpaF-WDM: SpeF and SpaF on fixed-grid WDM conditions with 50-GHz channel spacing including GB.

* D. Siracusa, F. Pederzolli, P. S. Khodashenas, J. M. Rivas-Moscoso, D. Klonidis, E. Salvadori, I. Tomkos, “Spectral vs. Spatial Super-Channel Allocation in SDM Networks under Independent and Joint Switching Paradigms”, ECOC 2015.

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Blocking results (under independent, joint and fractional joint switching)

BP vs. input load to the network for several SpaF allocation options and switching paradigms:

• Joint switching imposes a BP penalty compared to independent switching, which can be minimised through proper traffic engineering (better match between traffic profile and Tx maximum capacity)

1.E-4

1.E-3

1.E-2

1.E-1

200 400 600 800 1000 1200 1400

BP

Input Load [Erlang]

SpaF-InS

SpaF-FJoS

SpaF-JoS

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Number of WSSs required (under joint and fractional joint switching)

Joint switching can alleviate the cost problem associated with independent switching (resulting from the requirement of one WSS per fiber and degree) by allowing WSS-sharing between fibers.

Total number of WSSs required, under different switching paradigms, for a colorless, directionless R&S ROADM architecture in the Telefonica Spain national network:

Switching Number of WSS (general)Number of WSS

(Telefónica topology)

InS 2·Nd·D·S+4·NdA/D·S 2502

JoS 2·Nd·D+4·NdA/D 278

FJoS 2·Nd·D·S/G+4·NdA/D·S/G 834·: ceiling

S: number of fibersNd: total number of nodesNdA/D: number of nodes with

A/DD: avg. nodal degreeG: number of groups of

spatial modes (G = 3)

(For Nd = 30, NdA/D = 14, D = 3.7, S = 9, G = 3)

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Characteristic Distributed GMPLS Hybrid PCE/GMPLS Centralized SDN

Implementation complexity

Translate network model changes to OSPF/RSVP representation,

handle concurrent reservations in RSVP signaling

Same as GMPLS, plus extensions to PCEP to represent spatial

services

Develop the SDM network model from scratch, develop or extend

controller and north-bound interface

Computational Capability

Typically limited in scope (source routing based on limited

information) on multiple low power CPUs

Conceptually encompassing complex algorithms based on

extensive information and run on powerful, dedicated hardware

Conceptually encompassing complex algorithms based on

extensive information and run on powerful, dedicated hardware

Scalability / OverheadSlower reactivity due to large

increase in information to disseminate

Similar to GMPLS: more computational resource but small

pool of points of failure

Centralized controller gives high computational resources, south-

bound protocol can limit flooding

ResiliencyHigh (distributed system), but partition-crossing services fail

eventually

Only partitions which can reach the PCEs continue to operate, partition-crossing services fail

eventually

Data plane can use hard reservations, but CP partitioning would prevent controlling part of

the network

Programmability Not supported, and very difficult to retrofit

PCEP limiting as north-bound protocol, but could be adapted with

extra softwareSupported

Multi-domain/carrierSupported using e.g. BGP-LS to

flood information, but confidentiality issues

Supported, if nothing else through horizontal PCE chains

Open issue

Multi-vendorTheoretically supported (IETF

standard), but advanced features are mostly vendor-specific

Theoretically supported, relies on the underlying GMPLS control

plane

Depends on south-bound protocol, theoretically supported

INSPACE control plane framework: comparison of architectural archetypes

IN

Hybrid PCE/GMPLS was the choice for EU projects DICONET & CHRON – INSPACE now shifts to SDN

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INSPACE SDN controller architecture

Network Abstraction Module (NAM)

North-bound Communications Manager (NCM)

Topology Service (TS)

TDB

South-bound Protocol Manager (SPM) #1

Optical NodeCP Agent



Client Application

…Client Application

Client Application

TED Manager (TM)

PCE / RSSA Engine (PRE)

Virtualization Engine (VE)

Connection Manager (CM)

CDB

VDB

South-bound Protocol Manager (SPM) #2

1

512 13

4 6 2 8 3

971514

10 16

1711

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Summary

The activities of EU project FOX-C were presented® All possible spectrally flexible super-channel transceivers were implemented and tested® Nodes for all-optical add/drop of sub-channels (for both NWDM and AO-OFDM multiplexing)

were developed and tested ® Networking studies were performed to demonstrate the benefits of FOX-C solution

The activities of EU project INSPACE were presented® Nodes for independent or joint switching of SDM super-channels were developed and tested ® Networking studies were performed to demonstrate the benefits of INSPACE solution® Development of an SDN-based control plane for SDM-based networks is underway

The EU-funded projects FOX-C and INSPACE are developing the optical networking solutions that will dominate the market after 2020! • Stay tuned!!!

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Obrigado!

Acknowledgement

Dr. Ioannis [email protected]

to all partners of FOX-C and INSPACE EU projects

Flexible optical networking with spectral or spatial super-channels

Technology

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