IEEE ANTS 2013 Presentation This presentation evaluates the impact of SD-FEC technology upon network design and economics in a long haul optical transport network. The network study shows that the SD-FEC technology not only reduces the TCO (total cost of ownership) but also simplifies the network design. A real world network model is utilized to quantify and compare results.

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Network Economics of Optical
Transport Networks with SD-FEC
Technology
Anuj Malik*, Marco Sosa, Onur Turkcu, Vinayak Dangui,
Steve Hand, Matthew Mitchell, Serge Melle
IEEE ANTS 2013

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Introduction to Hard and Soft Decision FEC
log (BER)
(Lower is better)
Optical Signal to Noise Ratio (OSNR)
(Lower OSNR is easier to achieve)
Impact of better FEC is to drive down OSNR for a given BER
No FEC
1
Without FEC, a high OSNR is needed
to ensure a low Bit Error Rate (BER)1
HD-FEC
2
HD-FEC recovers bit errors, and
allows lower OSNR for a given BER2
SD-FEC
3
SD-FEC recovers higher levels of bit
errors, allowing even lower OSNR
for a given BER
3

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 Gen 1: G.709, Generic Hard Decision FEC
• 6.7% OH for 6dB Net Coding Gain
• Interoperable between vendors
 Gen 2: Enhanced Hard Decision FEC
• 6-10% overhead, up to 9.5dB NCG
• Non-interoperable between vendors
• Higher OH FEC in submarine
 Gen 3: Soft Decision FEC
• 15-35% overhead, >11dB NCG
• Non-interoperable between vendors
OTN FEC Evolution
Increasing
ASIC
Processing
Power

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The Impact of Overhead on NCG
Increase FEC OH
Q at FEC limit
Transmission Q Value
Lower OH FEC Higher OH FEC
Transmission Q penalty due to
the increase in FEC overhead
Y =
Improvement in Q
because of stronger FEC
X =
QdB = OSNR + 10*log10
BO
BC
Q is proportional to OSNR, but includes this term
describing optical noise level and receiver sensitivity
NCG
NCGNCG = X - Y

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Network Components for Case Study
 PIC Enabled Line Modules
 500G Per Slot
 ULH Reach
• HD-FEC: 9.2dB Coding Gain,
7% Overhead
• SD-FEC: 11dB Coding Gain,
15% Overhead
500G Tx PIC
500G Rx PIC
 Integrated OTN + DWDM Transport
 5T Integrated OTN Switching
 EDFA and Hybrid Amplifiers
 Less Power
 Less Space
 More efficient and Scalable

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 15596km fiber network
 11 total add/drop nodes
• 211 OLA Sites
 The traffic between data-
center sites generated
according to market data
available [www.datacentermap.com]
 Total traffic at Year i (Ti) is only
the growth over the initial
seed
• 𝑇𝑖 = 3.6 × 1 + 0.50 𝑖
− 3.6
Long Haul Datacenter/Express Network
NetworkTopologyDetails
Topology Details
# Links 11
Average Node Degree 2
Max Node Degree 2
Average Link Distance 1418 Km
Traffic Volume (Tbit/s)
Year 1 Year 2 Year 3 Year 4 Year 5
1.8 4.5 8.5 14.6 23.7

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Results – Number of Line Modules
0
50
100
150
200
250
300
350
400
0
50
100
150
200
250
300
350
400
Y1 Y2 Y3 Y4 Y5
SD-FEC Line Modules
HD-FEC Line Modules
Scenario 1: Only HD-FEC Line Modules Deployed
Scenario 2: Mix of HD-FEC and SD-FEC Line Modules Deployed
Up to 14% reduction in Line Modules with SD-FEC Technology

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Results – Regeneration Sites and Line system Amplifiers
0
1
2
3
4
HD-FEC HD-FEC and SD-FEC
Number of Regenerator Sites
66% reduction in Regenerator
Sites
0
100
200
300
400
HD-FEC HD-FEC and SD-FEC
EDFA Hybrid(RAMAN + EDFA)
Line System Amplifiers Deployed
Raman Sites dropped from
42% to 26%
Simplifies network deployment and minimizes network cost

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SD-FEC Benefits
Enables increase in optical performance and extends the
optical reach
TerrestrialSubsea
 Enhanced Optical Performance
 Can Close ULH Links > 10,000 KM
 Fewer Regen Sites
 Lower Network Costs
Benefits

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Conclusion
SD-FEC offers better optical performance and
longer reach than HD-FEC Technology
SD-FEC reduces TCO by reducing total number
of line modules and regenerator sites
SD-FEC simplifies the line system design by
reducing number of RAMAN Amplifiers

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Thank You

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Technology Comparisons
500G Tx PIC
500G Rx PIC
AOLM-500
HD-FEC based 500G Super-
Channel Line Module
9.2dB Coding Gain
7% Overhead
500G Tx PIC
500G Rx PIC
AOLM2-500
SD-FEC based 500G Super-
Channel Line Module
11dB Coding Gain
15% Overhead