Downloaded from orbit.dtu.dk on: Nov 19, 2018 Advanced solutions for inter- and intra-data center connectivity Vegas Olmos, Juan José Publication date: 2016 Document Version Publisher's PDF, also known as Version of record Link back to DTU Orbit Citation (APA): Vegas Olmos, J. J. (Author). (2016). Advanced solutions for inter- and intra-data center connectivity. Sound/Visual production (digital) General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. Users may download and print one copy of any publication from the public portal for the purpose of private study or research. You may not further distribute the material or use it for any profit-making activity or commercial gain You may freely distribute the URL identifying the publication in the public portal If you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.
Advanced Communications Technology Symposium Date & Time : 28 th April, 2016, 13:00-17:00 Venue : Osaka University, Nakanoshima Center 7 th floor, 702 class room Program : 12:30 Registration desk open 13:00 Welcome Remarks 13:15 (1) Recent Trends of North American optical network Hiroshi Onaka (Fujitsu) 13:25 (2) Optical fibers for long-haul and large-capacity optical communication systems Yoshinori Yamamoto (Sumitomo Electric) 13:45 (3) Optical performance monitoring for dynamic and flexible photonic networks Shoichiro Oda (Fujitsu Laboratories) 14:05 (4) A practical application of fixed microwave transceiver using radio over fiber (RoF) technology Kensuke Ikeda (Central Research Institute of Electric Power Industry) 14:25 (5) Underdetermined linear systems and problems in communications Kazunori Hayashi (Kyoto University) 14:45 Break 15:15 (6) On-Demand Wireless Networks exploiting Wake-up Receiver Hiroyuki Yomo (Kansai University) 15:35 (7) Coherent convergence of optical and wireless systems Toshihiko Hirooka (Tohoku University) 15:55 (8) Nyquist OTDM scheme using correlation detection and receiver bandwidth limitations. Yuji Miyoshi, Hirokazu Kubota, Masaharu Ohashi (Osaka Prefecture University) 16:15 (9) Optical transceivers for next generation optical access systems Satoshi Yoshima (Mitsubishi Electric) 16:35 (10) Advanced solutions for inter- and intra-data center connectivity Juan Jose Vegas Olmos (Technical University of Denmark) 16:55 Closing Remarks 17:00 End of the symposium 18:00-21:00 Party@Diamond Room in Rihga Royal Hotel
Advanced solutions for inter- and intra-data center connectivity J.J. Vegas Olmos, PD2008 DTU Fotonik, Technical University of Denmark (DTU), 2800 Kgs. Lyngby, Denmark,
Before we start Thank you Prof. Kitayama for your leadership within the field Good luck in your new endeavor 2
Motivation By 2016, 90% of the global internet/ IP WAN traffic passes through data centers. Cisco Global Cloud Index 3
Zettabytes per year Motivation DWDM Inter-Connection and Intra-Connections 12 10 8 6 4 2 0 Global Data Center IP Traffic Growth 2014 2015 2016 2017 2018 2019 25 % CAGR 2014-2019 Within data center 73.05% 75.44% 2019 2014 PAM-4 currently being standardized by IEEE P802.3bs 400GbE task force Data center - to - to - user - 18.21% 17.77% Data center - to - Data data center center - to - data 6.78% center 8.73% Source. Cisco Global Cloud Index 2014» Inter data center» Not standardized» Requirements are very different from short reach» Intra data center» Standardized» Constant increase opens up for non-standardized solutions (propietary) Chat Partners Social Search Service Cloud Community Phone Email Remember: we will need even more than now! 4
Outline of the talk»inter data center (SMF)» PAM-4» DMT»Intra data center (SMF and MMF)» DMT» PAM-4» Polybinary» Multi-CAP 5
Inter-DC 6
Data center-to-data center Requirements DWDM Data rates multiples of 400G Wavelength range C-band, EDFA amplification Optical dispersion compensation Several Tb/s link capacity, reach up to 100 km TX Low cost Low power consumption Novel & low-cost solutions are required! RX Low cost Low power consumption (Some) dispersion tolerance 7
DWDM Inter-Connections Why direct detection? Cost & Power Consumption Spectral Efficiency Long Haul Scale up or scale down? Short Reach» 400G coherent» 2 x 200G DWDM/ single λ 400G 16QAM 64QAM» 400G direct detect» 8x50G DWDM/ 4x100G WDM PAM-4 Similarities to IEEE P802.3bs 400GbE task force: 2km/10km over SSMF 8
PAM-4 for Inter-DC 400G DWDM TX 2 x 25.78125 GBaud PAM-4 PRBS DSP PRBS DSP DAC DAC + - - + PAM-4 Eval Board Real-time Generation & Detection 100G RX 2 x 25.78125 GBaud PAM-4 + - - + ADC DSP ADC DSP BER BER PRBS 31 PRBS 31 9
Experimental Setup 400G DWDM Odd channels DWDM 400G spectrum TX 2 x 25.78125 GBaud PAM-4 PRBS DSP PRBS DSP DAC DAC + - - + El. Driver, Bandwidth: 30 GHz MZM Bandwidth: 27.2 GHz MZM Even channels Interleaver, Bandwidth: 40 GHz w/o pre-eq 10
ROSNR @ BER=1e-3 Experimental Setup 400G DWDM TX 2 x 25.78125 GBaud PAM-4-8 dbm PRBS 80 km DCF DSP PRBS DSP EDFA DAC DAC + - - + El. Driver, Bandwidth: 30 GHz 80km & 100km VOA SSMF MZM Bandwidth: 27.2 GHz MZM VOA EDFA TDCM OSA Noise Loading Interleaver, Bandwidth: 40 GHz Res. Dispersion VOA DeMUX Bandwidth: 39 GHz CD-Tolerance of PAM-4 @ 25.78 GBd (Simulation) 30 28 26 24 + - PIN/TIA Bandwidth: 23 GHz FFE 11 FFE 23 FFE 5 0 2 4 6 8 10 12 14 16 Fiberlength [km] RX 25.78125 GBaud PAM-4 ADC DSP ADC DSP BER BER 11
Log(BER) Experimental Results B2B Performance -2-3 -4 ~ 29 db OSNR FEC-limit < 0.5 db in-band KR4 FEC Limit: 5.2e-5 0% overhead -5-6 -7-8 Single Channel - Lane 1 Single Channel - Lane 2 DWDM CH 4 @ 194.15 THz 24 26 28 30 32 34 36 38 OSNR [db]» Similar performance of both channels from the eval board» No significant influence of linear crosstalk 12
Log(BER) OSNR [db] Log(BER) -2-3 -4-5 -6-7 Experimental Results Launch Power 80 km Single Channel DWDM CH 4 @ 194.15 THz FEC-limit -6-4 -2 0 2 4 6 8 10 Launch Power per Channel [dbm] 40 38 36 34 32 30 28 26-2 -3-4 -5-6 -7-8 ~ 1.2 db FEC-limit Single channel - b2b Single channel - 80 km Single channel - 100 km 24 26 28 30 32 34 36 38 OSNR [db]» Optimum launch power:» Single channel: ~ 2dBm» DWDM transmission: ~ 1 dbm» ~ 1.2 db OSNR-penalty between b2b and 80 km at FEC-limit» No penalty between 80 km and 100 km at the FEC-limit 13
Log(BER) Log(BER) Experimental Results PAM-4 over DWDM Residual Dispersion and multichannel performance -1-2 -3-4 -5-6 FEC-limit DWDM CH 4 @ 194.15 THz ~ ±10 km -7-250 -200-150 -100-50 0 50 100 150 200 250 CD [ps/nm]» Residual Dispersion of approx. ± 170 ps tolerable -3 DWDM 80 km DWDM 100 km -4 FEC-limit -5 OSNR 31.5 db -6 OSNR 34 db -7 194 194.05 194.1 194.15 194.2 194.25 194.3 194.35 Channel [THz]» All channels stay below the FEC-limit 14
DMT as future technology More growth yet electronics need to catch up» The challenge with DMT is the same we will point out in the intra-data connectivity section: is DSP and electronics mature enough? 15
Intra-DC 16
Intra Data Center DWDM TX Low cost Low power consumption Bottleneck Transmitter performance Complexity of the DSP vs SE Data rates multiples of 400G Wavelength range C-band, EDFA amplification RX Low cost Low power consumption (Some) dispersion tolerance Optical dispersion compensation Novel & low-cost solutions are required! 100G, reach up to 10-100m MMF & 1-10km SMF 17
DMT Intra-DC Synchr. S/P S/P M-QAM TS IFFT CP P/S clipping FFT Equalizer P/S DMT as scalable technology using VCSELs 0 12 km SSMF d k DAC 80 GS/s Bias-T + + - DC Bias Bias-T VCSEL PIN-TIA - 30 GHz BW ADC 80 GS/s CP -1 TS -1 M-QAM -1 ^ d k Offline DSP 96 ch MUX 50 GHz grid Offline DSP 18
DMT Intra-DC Performance evaluation» 56 Gbit/s in 1.5 um over 12km SMF» Without dispersion compen.» 400G achievable for 8 channels» VCSEL technology» Low energy consump.» Low cost 19
PAM-4 Intra-DC Can we re-use PAM-4?» 25GHz bandwidth VCSELs being currently produced» PAM-4 is the logical next step after PAM-4» Which means, although the SE is good... You still need large bandwidth 20
PAM-4 Intra-DC Can we re-use PAM-4?» 100G solution with 25G class VCSELS» 0.5km attainable» 50G solution doable» 13km attainable» Low-latency PAM-4 Tx/Rx» Almost commodity electronics 21
5 km SSMF Intensity (100mV/div) Samples (a.u.) Polybinary Intra-DC Polybinary forgotten technology NRZ Duobinary 5 level Polybinary (5.5b/s/Hz) 7 level Polybinary (7.95b/s/Hz) Direct generation from an NRZ using only an electrical filter Duobinary-4-PAM Filtering DAC Driver Tx duo-4-pam atfer 5 km Histogram recovered duo-4-pam» Duobinary» NRZ as seed OOK 1 4-PAM Coding PRBS Generator OOK 2 Demapper + BER counter DSO TIA PD Time (5ps/div) Level (a.u.)» Polybinary» PAM as seed» Increased SE» Polybinary enables 100G operation in barely 5-6 GHz» It is however DSP intensive 22
dbm Optical power (dbm) -30-35 -40-45 -50-55 -60 Polybinary Intra-DC Performance 112Gbit/s Ca. 5GHz 3dB BW 0 3 6 9 12 15 Frequency (GHz) 10 0-10 -20-30 -40-50 Modulated Unmodulated -60 1552 1552,5 1553 Wavelength (nm)» Consistent power penalty up to 5km» No dispersion management straight SMF fiber» Single point and measure recovery algorithm» If dispersion kicks-in in you need complex DSP dispersion is key bottleneck» Same experiments at 56Gbit/s using VCSEL -1-1,5-2 -2,5-3 Optical b2b 1km SMF 2km SMF 5km SMF -7-2 3 8 Received optical power (dbm) 23
Power [mw] Voltage [V] Power [mw] Voltage [V] Power [dbm] Magnitude [db] MultiCAP Intra-DC Move down to 850nm and hit 100G AWG Bias-T VCSEL OM4 PR OSC I bias SM VCSEL LIV 0.8 4 0.6 3 0.4 2 0.2 1 0 1 2 3 Current [ma] 4 P max = -1.4 dbm MM VCSEL LIV 3 2 2 1 1 0 5 10 Current [ma] P max = 4.4 dbm 3 0-20 -40-60 Optical spectra MM SM 850 852 854 856 858 860 Wavelength [nm] 0-5 -10-15 -20-25 MM b2b MM 100 m MM 600 m MM 1000 m MM 1600 m MM 2200 m MM 24 0 10 20 30 40 50 Frequency [GHz]
MultiCAP Intra-DC Power [dbm] 107.5 Gbit/s MMF 10m Received electrical spectrum and constellation diagrams -30 Band 1 Band 2 Band 3 Band 4 Band 5 Band 6 Band 7 Band 8 Band 9 Band 10-40 -50-60 -70 0 5 10 15 20 25 [GHz] Band 1 Band 2 Band 3 Band 4 Band 5 Band 6 Band 7 Band 8 Band 9 Band 10 8.11% 8.01% 11.25% 11.56% 11.47% 11.48% 15.39% 15.34% 26.70% 40.40% BER and main parameters of MM-VCSEL 107.5 Gb/s transmission Band 1 2 3 4 5 6 7 8 9 10 Baud rate [Gbaud/s] Modulation 64-QAM 64-QAM 32-QAM 32-QAM 32-QAM 32-QAM 16-QAM 16-QAM QPSK BPSK Bitrate [Gb/s] 15 15 1 1 1 1 10 10 5 Power Loading [db] 2 1 0.3 0.6 1 2.1 1.2 2.6 0.4 2 Transmitted Bits 2174976 2174976 1812480 1812480 1812480 1812480 1449984 1449984 724992 362496 BER 3.12e-03 8e-03 2.36e-03 3e-03 3.76e-03 3.33e-03 2.63e-03 2.77e-03 7.89e-04 3.56e-03 25
MultiCAP Intra-DC Power [dbm] 107.5 Gbit/s MMF 100m -30 Band 1 Band 2 Band 3 Band 4 Band 5 Band 6 Band 7 Band 8 Band 9 Band 10-40 -50-60 -70 0 5 10 15 20 25 [GHz] Band 1 Band 2 Band 3 Band 4 Band 5 Band 6 Band 7 Band 8 Band 9 Band 10 7.32% 7.79% 10.01% 10.34% 10.51% 10.34% 13.10% 18.38% 29.42% 30.25% BER and main parameters of SM-VCSEL 107.5 Gb/s transmission Band Baud rate [Gbaud/s] Modulation Bitrate [Gb/s] Power Loading [db] Transmitted Bits BER 1 2 3 4 5 6 7 8 9 10 64-QAM 15 64-QAM 15 32-QAM 1 32-QAM 1 32-QAM 1 32-QAM 1 16-QAM 10 8-QAM 7.5 QPSK 5 QPSK 5 2 2.1-0.2 0.7 1.7 2.6 2 1.1-1 2.1 1449984 1449984 1208320 1208320 1208320 1208320 966656 724992 483328 483328 1.80e-03 2.94e-03 1.33e-03 1.58e-03 1.26e-03 1.89e-03 1.11e-03 1.66e-03 1.69e-03 2.08e-03 26
Log(BER) Bit rate [Gb/s] MultiCAP performance 120 110 100 90 80 0 200 400 600 800 1000 MMF Length [m]» Maximum bit rate below 7% FEC limit versus MMF length» 1km possible with 85 Gb/s -1-2 7% FEC» Application of more advanced FEC can extend the transmission distance» Do we add latency? -3 0 200 400 600 800 1000 MMF Length [m] 27
Conclusion...or rather open issues» Inter-data center» Right now upscaling NRZ/PAM seems the right way» Coherent around the corner cheap PICs will define the segment» Intra-data center» Multiple ad-hoc technologies to boost SE» Can electronics cope with the DAC/ADC requirements?» SMF vs MMF vs 850 vs 1310 vs 1550 CEEOALAN ABACUS 28
THANK YOU jjvo@fotonik.dtu.dk You can find us Metro-Access & Short Range Systems Contributors Nicklas Eiselt Annika Dochhan Helmut Griesser Idelfonso Tafur Monroy Rafael Puerta Jinlong Wei Michael Eiselt www.metroaccess.dk MetroAccess DTU Fotonik MetroAccessGroup Metro Access Photonics Engineering