elastic optical network
DESCRIPTION
EONTRANSCRIPT
Lecture: 9 Elastic Optical Networks
Ajmal Muhammad, Robert ForchheimerInformation Coding Group
ISY Department
Outline
Motivation Elastic Optical Networking
Flexible spectrum grid, tunable transceiver, flexible OXC Flexible Optical Nodes Routing and Spectrum Assignment Problem
Research Motivation
Emerging applications with a range of transport requirementFuture applications with unknown requirementsFlexible and efficient optical networks to support existing, emerging and future applications
Courtesy: High performance networklab., Bristol
High-speed data 400G, 1Tb/s
Media
Applications with Diverse Requirements
Courtesy: High performance networklab., Bristol
Evolution of Transmission Capacity
Spectral Efficiency (SE) ImprovementFixed optical amplifier bandwidth (~ 5 THz)
Per fiber capacity increase has been accomplished through boosting SE (bit rate, wavelength, symbol per bit, state of polarization)
Bit loading higher than that for DP-QPSK causes rapid increase in SNR penalty, and results in shorter optical reachSE improvement is slowing down, meaning higher rate data need more spectrum
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0 100 200 300 400 5000.01
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Bit rate per channel (Gb/s)
Rel
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e op
tical
reac
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ith
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per b
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Spe
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DP-QPSK
DP-16QAM
DP-64QAM
DP-256QAM
DP-1024QAM
QPSKBPSK
600
@25 Gbaud
Optical amplifier bandwidth (~ 5 THz)
TDM
WDM
Multiplexing technology evolutionPDM
Multi-level mod.
Current Optical Networks :: Inflexible
Super-wavelength
Courtesy: High performance networklab., Bristol
Current Solution for Bandwidth-Intensive Applications
Optical virtual concatenation (OVC) for high capacity end-to-end connection (super-wavelength)
Demultiplex the demand to smaller ones such as 100 or 40 Gb/s, which can still fit in the fixed grid (Inverse multiplexing)
Several wavelengths are grouped and allocated end-to-end according to the application bandwidth requirements
Grouping occurs at the client layer without really affecting the network
Connection over several wavelengths is not switched as a single entity in network nodes
Elastic Optical NetworkingThe term elastic refers to three key properties:The optical spectrum can be divided up flexibly
Courtesy: Ori Gerstel, IEEE Comm. Mag. 2012
Elastic TransceiversThe transceivers can generate elastic optical paths (EOPs); that is path with variable bit rates
Tunable transceiver Courtesy: Steven Gringeri, IEEE Comm. Mag. 2013
Flexible Switching
EONs
WDM Networks Bandwidth Variable
The optical nodes (cross-connect) need to support a wide range of switching (i.e., varying from sub-wavelength to super-wavelength)
Drivers for Developing the EONs Support for 400 Gb/s, 1Tb/s and other high bit rate demands
Disparate bandwidth needs: properly size the spectrum for each demand based on its bit rate & the transmission distance
Tighter channel spacing: freeing up spectrum for other demands Reach vs. spectral efficiency trade-off: bandwidth variable transmitter can adjust to a modulation format occupying less optical spectrum for short EOP and still perform error-free due to the reduced impairments
Dynamic networking: the optical layer can now response directly to variable bandwidth demands from the client layers
Elastic Optical Path Network:: Example
Elastic channelspacing
250 km 250 km
400 Gb/s 200 Gb/s 400 Gb/s100 Gb/s 100 Gb/s
1,000 km 1,000 km 1,000 km
Fixed format, grid
Adaptive modulation
QPSKQPSK200 Gb/s QPSK 16QAM 16QAM
Path length
Bit rate
Conventional design
Elastic optical path network
Outline
Motivation Elastic Optical Networking
Flexible spectrum grid, tunable transceiver, flexible OXC Flexible Optical Nodes Routing and Spectrum Assignment Problem
Common Building Blocks for Flexible OXCs
Reconfigurable Optical Add-Drop Multiplexer (ROADM)
Add channels Drop channels
Optical splitter Wavelength selective switch
Multi-Granular Optical Switching
FXC: Fiber switch
BXC: Waveband switch
WXC: Wavelength switch
BTF: Band to Fiber
Add channels Drop channels
Architecture on Demand (AoD)
Optical backplane cross-connections for AoD OXCs
MEMS switch is used to interconnected all theInput-output ports and switching devices
Courtesy: High performance networklab., Bristol
AoD NodeAimed to develop an optical node that can adapt its architecture according to the traffic profile and support elastic allocation of resources
Flexible OXC ConfigurationBackplane implemented with 96x96 3D-MEMSFlexibility to implement and test several switch architectures on-the-flySwitching time 20ms
Courtesy: High performance networklab., Bristol
Outline
Motivation Elastic Optical Networking
Flexible spectrum grid, tunable transceiver, flexible OXC Flexible Optical Nodes Routing and Spectrum Assignment Problem
Routing and Spectrum Assignment (RSA)
Spectrum variable (non-constant)connections, in contrast to standardWDM
Planning Elastic/Flexgrid Networks
Input: Network topology, traffic matrix, physical layer modelsOutput: Routes and spectrum allocation RSA(RMLSA include also the modulation-level used – 2 flexibility degree: modulation and spectrum)
Minimize utilized spectrum and/or number of transponders, and/or… Satisfy physical layer constraints
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Examples
RMLSA RSA
Courtesy: Ori Gerstel, IEEE Comm. Mag. 2012
Cost-Efficient Elastic Networks Planning Using AoD Nodes
Conventional ROADMs AoD ROADMs