Post on 14-Jan-2016
description
transcript
System engineering of alien wavelengths over the SURFnet network
Roeland Nuijts, SURFnet, roeland.nuijts@surfnet.nl
Customer Empowered Fiber Networks Workshop, Prague, Czech Republic, September 13th-14th, 2010
2
Outline
Introduction
Alien wavelength concept, advantages and disadvantages
Alien wavelengths in the SURFnet NGE (Next-Generation Ethernet) project
• Alien wavelength for metro-connections using small form factor 10Gb/s DWDM
interfaces on the existing SURFnet network
Alien wavelength for 40Gb/s long-distance SURFnet CBF connections
• mix 40Gb/s PM-QPSK and 10Gb/s NRZ-OOK on standard SMF (G.652) with
dispersion compensation
Conclusions
Alien wavelength concept
3
Rx
Tx
Tx
Rx
Rx
Tx
Tx
Rx
Tx
Rx
Rx
Tx
Rx
Tx
Tx
Rx
(a) conventional closed DWDM system
(b) multi-domain DWDM systems
(c) multi-domain DWDM systems with alien wavelength
Alien wavelength advantages
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• direct connection of customer equipment cost savings
• avoid OEO regeneration power savings
• faster time to service time savings
• support of different modulation formats extend network lifetime
Alien wavelength challenges
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• complex end-to-end optical path engineering in terms of linear (i.e.
OSNR, dispersion) and non-linear (FWM, SPM, XPM, Raman)
transmission effects for different modulation formats
• complicated system integration/functional testing
• end-to-end monitoring, fault isolation and resolution
• end-to-end service activation
Application of alien wavelengths in the SURFnet NGE (Next-Generation Ethernet) project
• Huge growth in data-oriented services over the past years
• Push for low-cost, flexible, hence, ethernet connections
• Until now Ethernet was transported over SDH/SONET
infrastructure as a means to re-use existing infrastructure
• With demand for more capacity and longer and high-capacity
connections (WAN instead of LAN) there is now need for Carrier
Ethernet
• SURFnet NGE (Next-Generation Ethernet) project
• SURFnet NGE project re-uses the existing DWDM layer
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SURFnet DWDM network - after Photonic Evolution project 1Q11
• All implemented ROADMs are of type 1x5 WSSes
• Convert remaining fixed OADM nodes to ROADMs
expensive maybe no time next year
• Zwolle, Enschede, Nijmegen, Wageningen, Delft, Utrecht
ready as of September 10th, 2010
• To be done: Asd1&2, remove fixed OADM in Ehv
• Enables:
• All-optical connection between TUD, TUE and TU
(three Universities of Technology)
• All-optical connection between Aachen (antenna
field in Julich and Astron/JIVE in Dwingeloo)
• All-optical pass-through between Amsterdam
locations to close optical DWDM rings
Alien wavelengths in the metro areaDWDM Architecture SURFnet6/7
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CIENA OME6500 and CPL
GMD
CMD
DSCM (dispersionCompensation)
10Gb/s WDM transmitter andreceiverOME6500 CPL
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Form factor improvement – 300pin to XFPTunable 50GHz channel spacing 10Gb/s DWDM transponder
300pin MSA transponderTypical power consumption 10W
Footprint: ±100cm2
XFP transponder Typical power consumption 3W
Footprint: ±14cm2
Example: optical specifications of JDSU XFP
Initial XFP exhibits negative chirp!Initial XFP exhibits negative chirp!
Transient chirp
g
(ps)
D(ps/nm km)
0
λ (nm)
λ (nm)0
A negative frequency excursion on the rising edge corresponds to a positive wavelength excursion which means group delay increases hence velocity decreases The opposite occurs on the falling edge Both result in pulse compression which counteracts pulse broadening by dispersion, hence more reach (or dispersion tolerance) Two methods to get negative chirp, unbalanced drivers or z-cut Mach-Zehnder modulators
Transmission performance versus dispersion with negative chirp
Optimum dispersion around +800ps/nm
In each DWDM ring there are paths from each OADM node to Amsterdam1 and Amsterdam2, tailored to +800ps/nm as close as possible. Consequently, paths between rings can have up to +1600ps/nm dispersion and paths between OADM nodes less dispersion. Sufficient system performance for these dispersion values needs to be verified before deciding to use low-cost 10Gb/s interfaces in the photonic layer for NGE
Optimum dispersion can not always be achieved in systems due to 2 reasons:• in systems due to “quantization error” of DCF spools (i.e. DCF10, 20, ….) • wavelength dependence of dispersion in transmission and compensating fibers
Calculate 10Gb/s wavelengths for NGE*
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1
2
7
6
5 3
8
9
1011
12
13
14
16
1718
19
21
22
2324
Alr01
Amf01
Asd01
Asd02Bd01
Ddt01
Dgl01Dt01
Ehv01Es01
Gn01Gv01
Ht01
Hvs01
Ledn01Mt01
Nm01
Rt01Tb01
Ut01
Wg01
Zl01
Alr01 14 21 1 7 7Amf01 29 7 7 2 14Asd01 81 45 7 80 8 46 9 44 38 18 16 20 18 14 78 15 37Asd02 19 7 9 9 23 16 14 26 18 25 14 21 35Bd01 14 1 4 14 1Ddt01 7 4Dgl01Dt01 22 14 12 1 14 27 1Ehv01 28 21 7 21 22 14 1Es01 7 23 9Gn01 7 7 7 1 39Gv01 14 21 1 14 3 14 2Ht01 14Hvs01 7Ledn01 21 7Mt01Nm01 1 7 23Rt01 1Tb01 28Ut01 2Wg01 14Zl01
LP+IP traffic
+
Network diagram
* Joint effort with Anteneh Beshir at the TUD (Delft Technical University)
Solved for required 10Gb/s wavelength connections and with minimum number of interfaces
Required 10Gb/s wavelengths for SURFnet NGE - only LightPath traffic
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Wavelengths
Nodes 1 2 3 4 5 6 Total
Amsterdam1 4 4 5 5 5 5 28
Amsterdam2 5 5 5 5 5 5 30
Leiden 0 2 0 2 2 2 8
Den Haag 0 2 2 2 0 2 8
Delft 4 4 4 4 4 4 24
Utrecht 0 2 0 2 2 2 8
Hilversum 0 0 0 2 0 2 4
Rotterdam 2 2 0 2 0 2 8
Dordrecht 2 0 0 0 0 2 4
Breda 0 2 2 2 0 2 8
Tilburg 0 0 2 0 0 2 4
Eindhoven 3 3 3 3 3 0 15
Den Bosch 2 2 0 0 0 2 6
Maastricht 0 2 2 0 0 - 4
Nijmegen 3 3 3 3 3 0 15
Wageningen 2 2 2 0 0 2 8
Amersfoort 0 0 0 2 2 2 6
Enschede 0 2 0 0 2 2 6
Zwolle 3 3 4 4 4 4 22
Almere 0 2 0 0 0 2 4
Groningen - - 2 2 0 2 6
Dwingeloo - - 0 0 2 2 4
Total 30 42 36 40 34 48 230
1. 230 10Gb/s interfaces required2. 82 different wavelength paths
required simulated optical transmission performance of all 82 wavelengths in order to verify whether these work and to check whether the first assessment of the FOM was correct
Simulation results of transmission performance- dispersion, received power and OSNR
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OSNRCalculated OSNR was well above ROSNR (Required OSNR) for each of the 82 paths
Measured OSNR of each 10Gb/s wavelength in the SURFnet network was well above the ROSNR
Required performance can be delivered by the new low-cost 10Gb/s interfaces!Required performance can be delivered by the new low-cost 10Gb/s interfaces!
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JOINT SURFnet/NORDUnet 40Gb/s PM-QPSK alien wavelength
DEMONSTRATION
W S S
W S S
10G40G
10G
W S S W S S10G
40G alien wave
10G
40G
416km TWRSAlcatel-Lucent
(with dispersion compensation)
640km TWRSNortel
(without dispersion compensation)
5x10Gb/s @ 50GHz
5x10Gb/s @ 100GHz350GHz
900GHz
End-to-end FoM = 1400 (a couple of dB margin over BOL OSNR limit - set against nonlinearities and
potentially adverse effect from filter concatenation [4])
Am
ste
rdam
Hamburg
Copenhagen
Ham
bu
rg40G
40G
Alien 40Gb/s wavelength transmission on SURFnet CBF connections
Alien 40gb/s wavelength on 10Gb/s-5x100km DWDM system using standard G.652 fiber and DCFs
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1 10 1 10
50GHz 50GHz
0 channels guard band
W S S W S S
10G40G
10G
5x100km SMF
34% pre-compensation
95% mid-span compensation
60% post-compensation
10G40G
10G
•Fairly unfavorable dispersion map due to zero-dispersion crossing at every span and hence high XPM efficiency
40Gb/sPM-QPSK
10x10Gb/s NRZ-OOK
10x10Gb/s NRZ-OOK
1x40Gb/s PM-QPSK
Simulation results 40Gb/s alien wavelength
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1 10 10
50GHz 50GHz
0 channels guard band
40Gb/sPM-QPSK
• The ROSNR of the 40Gb/s alien wavelength increases With increasing power level of the 10Gb/s NRZ-OOK channels, starting at about 4P, probably due to XPM• Increasing the power per channels of the 40Gb/s alien wavelength in the range where we conducted these simulations does not seem to affect (improve) the ROSNR so SPM (Self-Phase Modulation) does not affect the 40Gb/s alien wavelength• Best performance when 40Gb/s channel is stronger than 10Gb/s channels
P
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- We have investigated using low-cost 10Gb/s DWDM interfaces for the SURFnet NGE project by using a heuristic model to determine the required wavelength topology and a transmission propagation model to determine the required performance
- Simulation results show that new low-cost 10Gb/s XFPs deliver sufficient performance to be used for the NGE project and these results suggest they can be connected to the existing SURFnet DWDM layer
- Preliminary simulation results of 40Gb/s PM-QPSK transmission on a DWDM system with standard (i.e. G.652 SMF) and DCFs and equipped with 10Gb/s DWDM signals show that power of the 10Gb/s channels should be well below the power of the 40Gb/s channel in order to avoid XPM
Conclusions
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Acknowledgements
Some of the research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement nº 238875 (GÉANT)
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Thanks for your attention!
Questions?
roeland.nuijts@surfnet.nl+31-30-2305 305
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What limits system performance?ASE (Amplified Spontaneous Emission)
- Amplifiers are used to overcome fiber losses.- Optical Noise is added by each amplifier.- Engineering rules usually defined for equal spans (e.g. 20 x 20dB) which is not
the case in the real fiber networks
() = 2 h n sp (G() – 1)
Slide courtesy of Kim Roberts, Nortel
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OSNR (Optical Signal-to-Noise Ratio) - Simple formula
N
j jin
jsp
P
NRh
OSNR 1 ,
,21
Tx RxOA OA OA
SMFDCF
repeater
OA OA
DCFSMFSMF
Pin,1 Pin,2 Pin,3 Pin,N-1 Pin,N
NF1
NF2 NF3 NFN-1 NFN
Parameter Description
h Planck's constant (J•s)
c speed of light (m/s)
R OSA resolution BW (Hz)
Pin Input power (W)
Nsp Noise Figure (linear)
ƒ
OSNR
Resolution bandwidth = 0.1nm
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2729
3133
3537
3941
43
4547
49
0 40 80 120 160 200 240 280 320 360 400
Distance (km)
Cal
cula
ted
OS
NR
(d
B)
Simple formula, accurate to within a few tenths of a dB but sensitive information needs to be provided to fiber suppliers, which equipment vendors don’t like:• NF of amplifiers• launch power per channel• minimum required OSNR => need simplification
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In order to quantify optical link grade, we propose a new method of representing system quality: the FOM (Figure of Merit) for concatenated fiber spans
N
j
L j
FOM1
1010Lj, span losses in dBN, number of spans
FOMA 5504B 5504C 1897
120km 120km 120km 80km 80km 80km
80km 80km 80km 120km 120km 120km
Total 600km
100km 100km 100km100km100km 100km
A
B
C
New method to quantify fiberlink quality, FoM (Figure of Merit)