100-Gb/s Transport – A Reality Check
TNC2010, Vilnius, May 2010
Dr. Klaus Grobe, Sr. Principal Engineer, ADVA Optical Networking, Advanced Technologies
100G Transport Techniques
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Modulation Formats ABC
A transmitted signal s(t) can be described as:
Ak  A1 , A2 , ..., An ,
s(t )   Ak q(t  kT )
Aj  Aj  e
k
q(t) – pulse shape, Ak – symbols containing the information
RZ-OOK
NRZ-OOK
-
+
-
0 1
1
0 0 1
+
0 1 1 0
0 1
0 1
NRZ-DPSK
CSRZ-OOK
1 0 0 1
+
-
+ - - - + - 0 1 1 0 0 1
RZ-DPSK
+ - - - + - 0 1 1 0 0 1
PM-NRZ-DQPSK
Phase-Shift Keying (phase modulation)
Quaternary (4-state modulation)
Differential (pre-coding)
Non-Return-to-Zero (pulse shaping)
Polarization-Multiplexed (a.k.a. Dual-Polarization, DP, a.k.a. Orthogonally-Polarized, OP)
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j j
100G constellation diagrams…
Im
QPSK
Im
Re
6PSK
Im
8PSK
Im
8QAM
Re
Re
Re
 Various
modulation
schemes –
PSK, QAM, …
 NRZ vs. RZ
(duty cycle)
Im
Bipolar
6ASK
Im
Re
Im
16PSK
Re
4
9QAM
Im
DP-QPSK
Re
Im
16QAM
Re
Re
Re
Im
16QAM
Im
DP-8PSK
Im
DP-16QAM
Re
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Re
 Multi-carrier
 OSNR
optimum for
(DP-) QPSK
(coherent)
Cost-efficient 100G transport
 Different reach domains – 200 km vs. 2000 km
 Different requirements regarding protocol transparency, latency,
spectral efficiency, …
 Leads to (at least) two different implementations, using
different modulation at different cost points
LH / Backbone, <2000 km SMF
1 x 112 Gb/s (28 GBd) Coherent PM-QPSK
Enterprise, <200 km SMF
4 x 28 Gb/s DWDM / SCM
Different solutions at different cost points!
5
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Cost-optimized 100G
Transport
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High-speed Transport Roadmap
40G & 100G Transport Cards in FSP 3000
100G: LH
100G Carrier Core
40G: 1st Gen.
40G: Highly-Tolerant
40G Carrier Core
100G: Enterprise
100G Enterprise
2009
7
2010
2011
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2012
90°
QPSK
Coder
Driver
Filter
PBS
LO
PC
90°
90°
Hybr.
0°
Client I/F (CFP)
PBC
90°
FEC, Framing, Monitoring
PC
PBS
PC
Digital Filter (FFE)
CW
LD
0°
ADC
90°
90°
Hybr.
ADC
Driver
Filter
ADC
FEC, Framing, Monitoring
Client I/F (CFP)
QPSK
Coder
ADC
112G Coherent PolMux-QPSK
Im
PM-QPSK
 Highest performance 100G transport, but highest complexity (cost)
 Supports 50 GHz DWDM with 28 GBd and 2 (bit/s)/Hz spectral
efficiency, ROADM networking, and 1500…2000 km reach
 Digital filter for 4x28 Gb/s (necessary for Polarization demultiplexing,
dispersion compensation, etc.) not yet available
 ADVA is part of Georgia Tech consortium which follows PM-QPSK
8
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Re
ADVA Tests on PM-DQPSK w/ WSS
Transmitted over ~540 km (6 spans) with Wavelength-Selective Switches
 OSNR: 22.6 dB
 WSS, EDFAs and DCMs from current
ADVA product line
90°
28 GHz Clock
6X
PC
WSS
PC
EDFA
90 km SSMF
EDFA
PBS
PC
28 Gb/s Data B
DCM
Y Polarization
(Q)
(I)
Q = 3.83
9
(I)
Q =3.48
R
T-
R
WSS
PBS
X Polarization
T+
BERT
28 Gb/s Data A
CW
(Q)
Q = 3.09
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Q =3.24
Carrier Core Trans/Muxponder
 High-performance network interface
Im
PM-QPSK
 PM-QPSK with coherent detection (OIF standard)
 50 GHz channel spacing
Re
 Long-Haul capability
 >1500 km reach
 Dispersion (CD, PMD) compensation
 Strong FEC
 G.709-compliant mapping, multiplexing
 Services
 100GbE (IEEE802.3ba), OTU4 (G.709)
 10 x 10GbE / STM-64 / OC-192
4 Slots
10
4 Slots
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Low-Cost / Data Center 100G Transport
 Application areas
Why latency matters
 Storage/SAN connectivity
Reasons for (differential) latency
 LAN/HPC/Cloud connectivity
Link Group Delay, 100 km round-trip = 1 ms
 10GbE metro transport
Multiplexing, mapping, framing, typ. <100 µs
FEC, up to 100 µs, differential delay!
 Client protocols
 10x10GbE, native 100GbE
High-end requirements
 12x8G-FC, 6x16G-FC
Total delay, e.g., clustering, <10…100 µs
Differential delay, e.g., GDPS, <500 ns
 IB QDRx8, EDRx4
 Distance often <100 km
 Low latency
Counter-actions
Low-latency design
Avoid FEC
 Benchmark
Short links
 Cost of 10 x 10G DWDM T-XFPs
 2.5 x total system capacity compared to T-XFPs @ 50 GHz
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Rx
Rx
Rx
 Multi-Carrier Modulation - 4 directly modulated lasers (DML)
 4x28G, spectral efficiency 0.5…1 (bit/s)/Hz
 Low power consumption, very small footprint
 Low latency design, optional FEC bypass
()3
Optical Client I/F
+
4 x ODB Coders
DMX
R
+
DMX
~
R
R
R
Optical Client I/F
Proof of concept of 4x25G transmission in 100GHz
[K. Yonenaga et.al., JThA48, OFC/NFOEC 2008]
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Client I/F
Rx
FEC
Filter/Splitter
DML
ITU-T DWDM
DML
ITU-T DWDM
DML
4:1 Coupler
DML
FEC
Client I/F
Low-cost 100G Data Center Transport
100G Enterprise Muxponder
10TCE-PCN-10GU+100G
 Low-cost network interface design
 DML with enhanced dispersion tolerance
 Pluggable optics
 Clients: Multi-rate SFP+ 850/1310nm
 Network: based on CFP
CFP
4 x 28 Gb/s
DWDM
 4 x 28 Gb/s DWDM multi-carriers
 Record compactness
 2-slot card
SFP+
 800 Gb/s per shelf
 2 Tb/s per 80 channels / 50GHz
 6.4 Tb/s per ETSI footprint
 Complemented by 100GbE transponder
(WCE-PCN-100G)
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Implementation and Variants
Client
Interface
Module
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MDIO
Main Board
Quad
Laser Driver
DML
DML
DML
DML
Quad
PIN-TIA
CAUI
4:10
Gearbox IC
FCE
Skew Mgmt.
SFP+
Line OAM/ECC
…
1:10 Mux
SFP+
Rate Adapt.
SFP+
MLD/PCS Mon.
10x11.18G
4:10
Gearbox IC
Power Supply
MDIO/Ctrl.
Pluggable
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25 GHz Variants
25 GHz WDM Grid
100 GHz WDM Grid (SCM)
DML
25G-locked
DML
25G-locked
Power [dB]
DML
MX
DML
100 GHz
DWDM
-20
-40
-60
1
DX
DML
Quad
Laser Driver
DML
DML
DP-QPSK
DML
Quad
PIN-TIA
DML
Quad
PIN-TIA
Quad
Laser Driver
0
P
Optics Module
 Alternatively, 4x28G-to-100-GHz optics for Sub-Carrier Multiplexing
© 2010 ADVA Optical Networking. All rights reserved. ADVA confidential.
1
Normalized Frequency
 Filtered DML can directly support 25-GHz DWDM grid
15
0
100G Solution Comparison
16
100G Enterprise
100G Long-haul
Single/multi-Carrier
4 x 28 Gb/s DWDM (SCM)
Single Carrier
Modulation
NRZ Filtered DML with
Direct Detection
NRZ-DP-QPSK with
Coherent Intradyne
Detection + DSP
Spectral efficiency [b/s/Hz]
C-Band Capacity [Tb/s]
0.5…1.0
2…4
2
8
OSNR [dB], Reach [km]
22 dB w/ FEC,
28 dB SCM w/ FEC,
28 dB w/o FEC,
34 dB SCM w/o FEC,
CD Tolerance [ps/nm]
Mean PMD Tolerance [ps]
-250...+500 w/o TDC
5 @ 1 dB OSNR Penalty
>40,000 (FFE)
>30 (FFE)
Size (slots)
Power consumption [W]
2
95
4
120
Target Cost [relative]
50%
100%
600 km
200 km
200 km
50 km
15 dB, >1,500 km
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Conclusion
 Cost-optimized 100G transport needs differentiated solutions,
depending on applications’ reach (and spectral eff.) needs
 Data center / HPC also require low latency
 Mixture of high-performance Coherent DP-QPSK and low-cost,
latency-optimized Multi-Carrier Modulation
 Mix of two solutions does not cause significant OpEx mark-up,
but reduces CapEx significantly for DC/HPC/access applications
 100G deployment can start with low-cost variant, moving these
transport cards to less-utilized links later
17
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Thank you
KGrobe@ADVAoptical.com
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