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Waveguide Optics
Teacher : Lilin YiEmail : [email protected] : SEIEE buildings 5-517Tel :34204596
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State Key Lab of Advanced Optical Communication System and Networks
Chapter 11 Beyond 100G
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Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view
Technical Trend beyond 100G
DSP = doesn’t save powerHow to reduce the power consumptionBeyond 100G options400G or 1T?higher bit rate per channelFlexible grid - WSSBroadband amplifiers – Raman and hybrid Raman/EDFA
Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view
Example ADC/DAC/DSP applications
What is driving ADC/DAC/DSP choices
Single chip CMOS ADC/DAC/DSP
Power consumption for ADC/DAC
ADC power consumption ~1.5W/ch in 40nm~6W for Rx DAC power consumption ~0.75W/ch in 40nm~3W for Tx
Power consumption for DSP
4k bits at ADC/DAC, >90% power dissipation is in interconnectInitial power estimates are “always” too lowEven experienced digital designers underestimate “power creep”Once a team has done 100G, then you can believe the power numbers…
Thermal performance
A “gold-plated” package solution
Example 100G chip and HiTCE LTCC substrate
Future challenges - technical
Future challenges - commercial
Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view
Modulation formats background
Modulation formats background
Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view
System vendor view - NSN
Transponder architectures beyond 100G Transmitter and receiver remains little changed (PDM-QPSK PDM-16QAM)Optical components spec is more stringent for QAM modulation, requiring ADC with higher number of effective bits, laser with smaller linewidth, more advanced DSP algorithmMajor challenge is the line system itself
System vendor view - NSNOSNR penaltyQPSK 16 QAM, 3.7dB ↑100G PDM-QPSK 200G PDM-16QAM, 6.7↑14dB @ 1E-3 BER vs. 20.7dB @ 1E-3 BER Non-ideal transmitter architecture, 24-26dB @ 1E-3 BER for 200G PDM-16QAM
Nonlinear threshold penaltyThe highest maximum power of a constellation point increase relative to the average power of the signal100G PDM-QPSK 200G PDM-16QAM, at least 5dB power penalty
Maximal reach100G PDM-QPSK 400G PDM-256QAM, 3% reachIt is impossible to transmit 400G line rates within a 50-GHz WDM grid as the maximal reach is only several hundreds of kms for even the most optimum system400G and 1T is more than a change of the modulation format
System vendor view - NSNCurrent fixed-grid networks
• PDM-QPSK, 4b/s/Hz in theory vs. 2b/s/Hz in reality (50GHz grid) • After 20 cascaded WSS with 4th order Gaussian 3-dB bandwidth of
45GHz, the bandwidth becomes 31GHz, corresponding to 31Gbaud/s signal. Only 62% (31/50) of the actual bandwidth is used with the current WSS technology.
System vendor view - NSNSuper channels: multiple signals or spectral bands are transmitted as a single entity, enabled by flexible WSS technology – a software defined definition of the filter passband. (flexi-grid networks)
• 400G – combine four bands of 100G PDM-QPSK, cosine pulse shaping “square” optical spectrum, 400G line rate 132GHz bandwidth 150GHz flexi-grid channel spacing 88% effective bandwidth (2.67b/s/Hz)
• 400G – combine of two bands of 200G PDM-16QAM 66G bandwidth 87.5GHz flexi-grid channel spacing 76% effective bandwidth
• 1T – combine 5 bands of 200G PDM-16QAM 165G bandwidth 187.5G flexi-grid channel spacing maximal capacity of 25Tb/s in C band
To use 90% of the actual bandwidth, a 225GHz channel spacing is required with the current WSS technology (solid line, 4th
order, 45GHz ) . For next-generation high-definition WSS (dotted line, 6th order, 47GHz), the channel spacing is reduced to 150GHz.
System vendor view - NSN
Fiber infrastructure optimizationNew fiber with low span loss and low nonlinearity – large effective area pure-silica-core fiber (LA-PSCF) 0.16dB/km, 130um2
It remains to be seen if the increase in fiber capacity outweighs the immense deployment cost of new fiber infrastructureHybrid EDFA/Raman amplification – improve OSNR
System vendor view - Ciena
Current situations100G performance is now similar to 10G, only after applying DP-QPSK modulation coupled with a coherent receiver and advanced FEC.
ProblemsFEC is approaching the Shannon limitMore complex modulation formats, such as 16 QAM, have a higher sensitivity to noise, requiring more frequent regenerationChannel power cannot be increased significantly due to nonlinearities.
SolutionsFlexible grid ROADM – arbitrary configuration is difficultMaximize the symbol rate based on the current coherent detection technologySoftware configurable modulation formats Supper-channelNew fibers, new amplifier technologies and different amplifier spacing
Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view
Carrier view – Verizon100G live deployment Paris to Frankfurt 893km13 spansno regenerationOperational Dec. 2009Add 100Gb/s router in 2010
Carrier view – VerizonThirst for more
Carrier view – VerizonBandwidth scalability
Carrier view – VerizonFlexible Bandwidth Grid
Carrier view – VerizonFlexible Layer1 Network
Carrier view – VerizonWhat’s Next?
Carrier view – Verizon
Carrier view – AT&T
Coming soon in fiber transmission An integrated photonic module and a MSA transceiver module for 100G PDM QPSK
Coming soon in photonic networkManual reconfigurable RODAM Software configurable CDC ROADM + tunable transponder
Carrier view – AT&T
Beyond soon in fiber transmissionWhat will follow the 100G, coherent systems?CD with DSP is powerful, but new for fiber community and its evolution is unclearThe current system is approaching its capacity limit, modification is required to mitigate fiber nonlinearitySingle carrier multi carrier, although “flexible grid” improve the spectral efficiency, come at a painful price in terms of operational complexity
Beyond soon in photonic networkFully configurable ROADM will be a big improvement, but connecting “clients” to the transponders is still a manual processSimplify and speed up installation and turn-up of connections by inserting a “client-side” cross-connect
Carrier view – AT&T
ConclusionsCarrier today must: 1. Learn how to handle transmission systems with coherent detection and DSP; 2. Develop new processes to take advantage of colorless and non-directional ROADMs to enable efficient and agile photonic networks.In a few more years, 400G at the expense of shorter reach, the need for Raman amplification and/or new fiber installations. It is quite possible the per bit cost will not be less than the previous generation. Feasibility? Will come down to the overall network economics.
Outline
Technical trends beyond 100GLower power consumption for 100G transponderTechnical Options for 400G or 1TSystem vendors viewCarriers viewBusiness view