flexible optical networking with spectral or spatial super-channels
TRANSCRIPT
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
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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
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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
re C
apac
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
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Spectrally flexible optical networking
The activities of EU project FOX-C
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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
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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
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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
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FOX-C system test-bed
Testbed assembled at FT/Orange Labs premises:
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Experimental characterisation of flexible transceivers
BER vs SNR
ROF: Roll-off factor
NWDM e-fOFDM
Nyquist FDM MB-eOFDM
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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
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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
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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
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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
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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.
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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
24
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!!!
25
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
26
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
27
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
28
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.
29
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
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
car
eful
with
:
dBUFFER=250m
dCLADDING=125m
dCORE=8m
SMF
36
Degrees of freedom in SDM transmission
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
car
eful
with
:
Bundle of SMF
(A) Uncoupled spatial modes
37
Degrees of freedom in SDM transmission
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
car
eful
with
:
Bundle of SMFMCF
(A) Uncoupled spatial modes
38
Degrees of freedom in SDM transmission
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
car
eful
with
:
MCF
(A) Uncoupled spatial modes(B) Coupled spatial modes
39
Degrees of freedom in SDM transmission
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
car
eful
with
:
MCF
40
Degrees of freedom in SDM transmission
Core count Mode count Cladding diameter Core layout
• Geometry• Homo-/heterogeneous core
structure
Refractive-index profile• Graded-index• Step-index• Trench-assisted
Inter-core crosstalk Inter-mode crosstalk Differential mode group
delay (DMGD) Bend loss Nonlinearity Process variabilityBe
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
SDM switching classification
Independent spatial/spectral channel switching Spectral channel switching
Spatial channel switching Spectral channel switching of spatial subgroups
(A)
R&S node design for independent spatial/spectral channel switching
* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)
47
SDM switching classification
Independent spatial/spectral channel switching Spectral channel switching
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
* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)
48
SDM switching classification
Independent spatial/spectral channel switching Spectral channel switching
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
* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)
49* D. M. Marom et al.,''Switching Solutions for WDM-SDM Optical Networks'', IEEE Comm. Mag. 53, 60-68 (2015)
SDM switching classification
Independent spatial/spectral channel switching Spectral channel switching
Spatial channel switching Spectral channel switching of spatial subgroups
(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
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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
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SDM technology elements
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
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SDM technology elements
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
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SDM technology elements
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.
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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
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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
Optical NodeCP Agent
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