OPTICAL ENGINEERING 2014 ORT Hermelin College Wednesday, February 26, 2014 " ,' " ,

Enabling Technologies and Challenges in Coherent Transport Networks

David Dahan, Ph.D.

ECI Telecom Ltd.

Drivers and Impact for Optical Networking Ecosystem

Video and more Video….

Internet streaming Shifting to the Cloud… Enterprise and personal IT are moving to the cloud computing Service Providers become “All Play” providers…

IP Video Traffic 90%

Other IP Traffic

2013 - IP at 5x 2008 levels with 90% Video Exponential Traffic Growth Dynamic Traffic Networks Technology challenges Need more optical channel capacity : 100G/400G/1T Improve service provisioning, time and resource utilization : SDT/ROADM/SDN Slow Revenue Growth Business challenges Reduce cost /bit/switch/transport

Confidential , not for distribution 2

Optical Network Evolution

History and roadmap

2006 2.5G

CWDM, DWDM

      SDH / Sonet Networks Increase capacity Point-to-point CWDM/DWDM Up to 40 channels 2.5/10G channels

2008 10G 40 Channels

      SDH / Sonet / EoS services support Ring topology East/west protection Reconfigurable OADM WDM over OTN 10G channels

2012 2011 40G 80 Channels

     IP over WDM Mesh topology ASON GMPLS-based ODU basednetworks  10G/40G channels, ready for 100G coherent Plug and play

40G/100G Coherent

    100G Coherent networks support DCFless networks Colorless / directionless / contentionless WSON GMPLS based

Continued demand for bandwidth from all applications 2015 400G/1T Superchannel

     Bandwidth on Demand N:M ROADM configuration Gridless ROADM 400G/1T transceivers Fully automated network Confidential , not for distribution 3

From Direct Detection to Coherent Detection

Up to 10G (SE = 0.2 b/s/Hz)    40G/100G/200G coherent solution (SE > 2 b/s/Hz)

Intradyne Coherent detection

Phase and polarization diverse receiver Frequency Locked Lasers (<+/- 2 GHz) Digital Signal Processing at TX/RX 40G non coherent solution (SE = 0.8 b/s/Hz) TX RX Confidential , not for distribution 4

Current 100G Coherent Transceiver architecture

Modulation format : DP-QPSK (Symbol Rate is ¼ Bit Rate : 2bit/s symbol x 2pol) Integrated PDM QPSK MZM LiNBO3 Modulator Integrated Coherent receiver

40 nm CMOS ASIC with 4 (8 bit resolution) x63 Gsamples/s ADC

5

Current 100G Coherent Transceiver architecture

Coh. Rx

S LO I x 90 ° Hybrid & Detector Q x I y Q y

120G

ADCs

j j D>60000 ps/nm

DSP block

PMD>30 ps OTU4 112G

Gen Type Code

1 st 2 nd 3 rd HD HD SD BCH (Bose-Chaudhuri-Hocquenghem) and RS (Reed-Solomon) codes Concatenation of RS codes, Viterbi convolutional codes and BCH codes (CBCH) BCT (Block Turbo code) or Turbo Product Code (TPC) and LDPC (Low Density Parity Check) codes 6-8 bits

FEC Over head

7%

Pre-FEC BER TH. For post FEC<10 -15

~10 -4 7% 15% 20% ~1x10 -3 (EFEC) ~2x10 -2

Coding gain [dB]

6-7 dB 8.5-10 dB 10.5-11.5

dB 1 bit +reliability bit info Confidential , not for distribution 6

100G submarine Field trial over 4600 km

The 100G trial was carried out over Bezeq International’s live operational submarine fiber, in conjunction with the TeraSanta Consortium : demonstration of advanced capabilities of ECI 100G transmission system and technologies in compensating for non-linear channel impairments and chromatic dispersion utilizing advanced SD-FEC algorithms.

100G DMUX Apollo Platform 100G MUX Confidential , not for distribution 7

Next Generation of Coherent Transceiver : : Software Defined Transceiver (SDT)

28 or 20 nm CMOS ASIC with DAC/ADC and DSP capabilities in both TX/RX



Power reduction



Higher computational strength



Adapt modulation format/Symbol rate Technol.

Gate

28 nm 20 nm 150 200M 200 250M

ADC (8bits)

110-130 GS/s 1.7W

110-130 GS/s 1.2W

DAC (8bits)

110-130 GS/s 0.7W

110-130 GS/s 0.5W

GA

2013 2014

Si Photonics IC with Electronic and Optical functionality Client Data Rate 100G/150G/200G /400G/1T FEC overhead 0%-30% Modulation format BPSK/QPSK/ 8-QAM/16QAM TX DSP Optical Carrier Pulse Shaping Flexgrid tunable laser (C/L band)

Confidential , not for distribution 8

New DSP features

■ Nyquist spectral shaping at TX : increases of the spectral efficiency by reducing the channel bandwidth to ~ symbol rate -2 -3 -4 1 0 -1 4 3 2 1 2 3 4 5 symbol index 6 7 8 Raised Cosine FIR filter 0.8

0.6

0.4

0.2

0 -0.2

0 2 4 6 8 10 Tap index 12 14 16 18 Confidential , not for distribution 9

New DSP features

■ Self diagnostic monitoring features : ■ Accumulated Chromatic Dispersion monitor ■ PMD monitor ■ OSNR monitor ■ ESNR monitor ■

Still missing

: Efficient nonlinear compensation technique ■ Current state of the art techniques based on digital back propagation or Volterra Series are too complex for real time ASIC implementation ■ Nonlinear optical impairments are the ultimate limitations in optical network Confidential , not for distribution 10

4x120G

Transmission Technology options for 400 Gb/s

Modulation Gbit/s

Symbol Rate DP-QPSK 120 DP-16QAM 240 f

4 bands with DP-QPSK (30Gbaud)



No spectral efficiency



improvement over 100G Suitable for long haul (>2000 km)

90 Gbaud 60 Gbaud DP-16QAM DP-256QAM 480 480 30 Gbaud QPSK 8-QAM 16-QAM 32-QAM 64-QAM

1 bands with DP-16 QAM (60 Gbaud)



High spectral efficiency



Reach Limited to Metro (~700 km)

2 1 Reach Limited <<100km 3 1x480G Subcarriers/band 4

2 bands with DP-16 QAM (30 Gbaud)



High spectral efficiency



Reach Metro /Long Haul distances

2x240G

OSNR min [dB]

12.5

18.5

21.5

>30 256-QAM Constellation size

1 bands with DP-256 QAM (30 Gbaud)



Extremely high spectral efficiency



Reach Limited (~100 km)

1x480G f f Confidential , not for distribution 11

TX

Hybrid Raman Amplifiers

Improving transmission reach ■ ■ Complex Coherent modulation formats like 200G DP-16QAM require for 6-8 dB OSNR improvement with respect with current 100G DP-QPSK modulation format The use of hybrid Raman-EDFA amplification schemes is required to improve the received OSNR or mitigate the nonlinear penalties by lowering the launched power into the fiber : can improve the transmission reach by 100% x N times ROADM EDFA L km EDFA ROADM EDFA RX 10 5 5 5 0 0 0 -5 -10 -15 -20 -25 0 0 0 20 40 60 Fiber Length [km]

With Hybrid Raman –EDFA amplification

80 100 Confidential , not for distribution 12

Superchannels

Improving spectral efficiency beyond 100G ■ Future services of 400Gb/s and 1T will be packed into super channels, in order to provide optimum flexibility and reach performance tradeoffs : ■ 400G : 2 channels spaced by 37.5 GHz ■ 1T : 5 channels spaced by 37.5 GHz ■ For optimized spectral efficiency, Super channels use Nyquist spectral shaping and Flexgrid WSS ROADMs Confidential , not for distribution 13

Flexgrid Networks

■ ■ To increase spectral efficiency, we move from a fixed channel grid (50GHz/100GHz) to flexible channel grid management : ■ ■ 6.25 GHz grid 12.5 GHz bandwidth granularity The channel spectral slot is adapted on a per channel basis using : ■ 10G/ 40G on 25 GHz slot ■ ■ ■ 100G and 200G on 37.5 GHz slot 400G on 75 GHz slot 1T on 187.5 GHz slot 400G 100G 1T Fixed 50GHz grid 40G 10G f 50 GHz Flex grid 400G 100G 1T 10G Increase by 25 % the available useable fiber bandwidth 50 GHz 40G f Confidential , not for distribution 14

Flex Grid Technology enablers

■ Very stable tunable lasers compatible with 6.25 GHz grid resolution ■ Flexgrid ROADMs : ■ First generation of WSS allocated a channel on a single MEM based pixel ■ Flexible WSS based on LCoS technology use a flexible matrix based wavelength switching platform with megapixel matrices allowing programmable channel bandwidth * EXFO Webinar : “400G Technologies: the new challenges that lie ahead”,04/02/2014 http://www.exfo.com/library/multimedia/webinars/400g-technologies-challenges Confidential , not for distribution 15

Optical Network Node with Full Flexibility

■ Network node capabilities are enhanced with new features allowing full flexibility : ■

Flexgrid : any channel/ superchannel can be directed towards any other node

■ ■ ■ Colorless Directionless Contentionless Confidential , not for distribution 16

Optical Network Node with Full Flexibility

■ Network node capabilities are enhanced with new features allowing full flexibility : ■ Flexgrid ■

Colorless : any wavelength can be added or dropped at any port

■ ■ Directionless Contentionless Confidential , not for distribution 17

Optical Network Node with Full Flexibility

■ Network node capabilities are enhanced with new features allowing full flexibility : ■ Flexgrid ■ Colorless ■

Directionless : any wavelength can be directed at any direction an reach a given port

■ Contentionless Confidential , not for distribution 18

Optical Network Node with Full Flexibility

■ Network node capabilities are enhanced with new features allowing full flexibility : ■ Flexgrid ■ Colorless ■ Directionless ■

Contentionless : Multiple channels of the same wavelength can be dropped or added by a single module

Confidential , not for distribution 19

Optimum management of the optical spectrum resources



Optimized routing and resource allocation algorithms for flexible optical networking

 Conventional Routing and Wavelength Assignment (RWA) algorithms can be used only for rigid grid networking  New paradigms based on Routing and Spectral allocation Assignment (RSA) algorithms should be developed for flexible grid networking  overhead) will be required Rigid grid network defragmentation Flex grid network Confidential , not for distribution 20

Software Defined Networking : Why ?

Flexible Multi-layer Networking ■ Bandwidth hungry services (video, mobile data, cloud services) lead to new traffic characteristics : ■ Rapidly changing traffic patterns ■ High Pic to average traffic ratio ■ ■ Large Data chunk transfers Asymmetric traffic between nodes ■ SDN will turn the networks into programmable virtualized resource for better efficiency and automation Confidential , not for distribution 21

User I/Fs

Software Defined Networking

Flexible Multi-layer Networking Network Apps Open APIs Application requirements

Dynamic connectivity Bandwidth QoS Resiliency SND Control Plane

Hardware Abstraction & Virtualization SDN Control Plane

Aware of Application requirement Optimized resource and configuration

OpenFlow Multi layer Network Elements Ethernet switch/MPLS router OTN switch ROADM, SDT Fiber switch Confidential , not for distribution 22

Conclusion

■ The future optical transport networking will provide better ■ Capacity : coherent modulation formats, superchannel, better SE ■ Flexibility : software defined transceivers, flexible grid, flexible CDC ROADMs nodes ■ Resource utilization : impairment aware- RSA algorithms, SDN ■ The future optical transport networking needs to provide : ■ Efficient nonlinear optical impairment compensation techniques ■ Strategies for pro-active and re-active spectrum defragmentation and fragmentation awareness in service expansion and contraction policies ■ ■ Energy efficient strategies Capex and Opex reductions Confidential , not for distribution 23