Advances in Unrepeatered Submarine Systems · Advances in Unrepeatered Submarine Systems NANOG45...
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Transcript of Advances in Unrepeatered Submarine Systems · Advances in Unrepeatered Submarine Systems NANOG45...
2© 2008
Outline
• Status of un-repeatered technology• Advances in un-repeatered submarine
technologies• Applications
– Extending the life of existing systems– Longer reach– Higher capacity
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Technologies for Longer Reach & Higher Capacity
LongerReach
HigherCapacity
UltraLow-Loss
Fiber
AdvancedModulationFormats
HigherLine rate
AdvancedError
Correction
NovelAmplification
Scheme
TighterChannelSpacing
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Amplification
Erbium Doped Fiber
Coupler IsolatorIsolator
1480Pump Laser
Pump λ’s
Amplified λ’s
Discrete Amplifier
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Discrete Raman Amplifier
Gain Fiber
Coupler IsolatorIsolator
Pump Lasers
Pump λ’s
Amplified λ’s
Discrete Raman Amplifier
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0 50 100 150 200 250 300 350 400 450
Distance (km)
Sig
nal
po
wer
(dB
m)
~ 300 km
Status of Un-Repeatered Submarine Systems (1)
Booster amplifier Pre-amplifier
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Distance (km)
Sig
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Booster amplifier Pre-amplifier
Status of Un-Repeatered Submarine Systems (3)
~ 360 km
ROPARemoteOpticallyPumpedAmplifier
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Distributed Raman Amplification
Line Fiber
Coupler IsolatorIsolator
Pump Lasers
Pump λ’s
Amplified λ’s
Site 1 Site 2
Distributed Raman AmplificationDistributed Raman AmplificationUses the transmission fiber between amplifier sites as the gain fiber
Benefits– Improved noise figure & reduced non-linear
penalty– Longer amplifier spans, support of higher line
rates, operation near zero dispersion wavelength
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Distance (km)
Sig
nal
po
wer
(dB
m)
Booster amplifier Pre-amplifier
Status of Un-Repeatered Submarine Systems (2)
~ 360 km
DRADistributedRamanAmplification
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All Raman Amplification
Amplified λ’s
Discrete AmplifierDistributed Amplification Discrete Amplifier
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Distance (km)
Sig
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Booster amplifier Pre-amplifier
Improved Reach with All-Raman Amplification
~ 450 km
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Improved Capacity with All-Raman
All-Raman technology allows cost-effective combinations of reach and channel count that are unattainable in erbium-based systems
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1400 Wavelength(nm)
Fiber
att
enuat
ion (
dB/k
m)
Chro
mat
ic d
isper
sion (
ps/
nm
/km
)
0.4
0.2
0
10
20Standard fiber(ITU-T G.652)
Typical NZDSF fiber(ITU-T G.655)
Typical DSF fiber(ITU-T G.653)
Minimum fiberattenuation
1619 nm1593 nm1568 nm1543 nm1519 nm
100-nm opticalbandwidth
Pure Silica Core Fiber(ITU-T G.654)
TypicalLS fiber
Band # 4 Band # 3 Band # 2 Band # 1
1500 1600StandardC band
Optical Bandwidth vs Fiber Spectral Characteristics
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All-Raman Enabled Distance & Capacity
End of Life Cable Loss (dB)10 20 30 40 50 60
10
20
30
40
50
60
70 80
Num
ber
of
Chan
nel
s @
10 G
b/s
90 100
Performance of somedeployed systems
Notes:- G.652 / G.654 fibers- Enhanced FEC- ROPA at 100 km from receive terminal
Wit
h R
OP
A
520 kmwith low-loss G.654 fiber &> 6dB margin
460 kmwith high-quality G.654 fiber &> 7dB margin
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Advanced Error Correction
• FEC, EFEC, UFEC• Upgrades to older systems have up to 6 dB effective gain • Even on standard systems effective gain of up to 2 dB by
going from 7% to 25% overhead
5 Overhead (%)
Theoretical limit
10 15 20 25 30
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6
7
8
9
10
11
Net coding gain (dB)
"Standard"
Newer
“Older"
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Log(
BER)
Q [dB]
UFEC Performance
FECEFECUFEC
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10-15 10-13 10-12
Target Q [dBQ] 18.0 17.3 16.9Gain at Target BER [dBQ] 8.6 8.0 7.7Pre-EFEC Target Q [dBQ] 9.4 9.3 9.2Gain at Target BER [dBQ] 9.8 9.2 8.9Pre-UFEC Target Q [dBQ] 8.2 8.1 8.0
EFE
CU
FEC
Target BER
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Advanced Modulation Formats
1 0 1 1 0
DPSK signal
Delayed signal
Combined signal
• DPSK = Differential Phase Shift Keying– Encoding:
• “1”: phase is the same as previous bit• “0”: phase is inverted
– Detected by splitting and re-combining after one bit delay
Quasi-coherent detection; gives ~ 3 dB improvement
1 0 1 1 0
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Higher Line Rate
• 40Gb/s transmission
Fiber type: ITU-T G.654Length: 468 kmLoss (@ 1550nm): 82 dBODF scenario: SplicesLine rate: 43Gb/sModulation format: NRZ-DPSK
192009
Transmission of 10ch at 40G over 468km (82dB)
Spectra
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1568 1570 1572 1574 1576 1578 1580
Pow
er [d
Bm
]
wavelength [nm]
transmited spectrumt
received spectrum
7
8
910
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1415
16
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1570 1572 1574 1576 1578
wavelength [nm]O
SNR
, Q [d
B]
OSNR Q E2FEC Q @ BER<1e-15
OSNR
Q
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PoP
Lan
din
gst
ati
on
PoP
Lan
din
gst
ati
on
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Design Simplification (1)
Placement of SLTE in PoP
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Design Simplification (2)
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OA OAOA
Upgrade of older generation systems
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ARCOS Upgrade
• 22 unrepeatered segments– 10 with ROPAs
• Longest=394km (with ROPA)
• Highest loss=78.4dB (EOL)– Max capacity=23x10G
• 5 to 11x capacity increase
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Irish Ring
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Summary
• Submarine Fiber Systems vital to continued globalization
• Unrepeatered Submarine systems pivotal for both intra-regional and global connectivity
• Novell Amplifier design using All-Raman amplifications continues to push the limit for distance and capacity
• A key benefit of all-Raman is the ability to upgrade existing unrepeatered and short repeatered links
