optics ppt
- 2. Introduction Overview on ROADM Flexible Optical Network • Functionality requirements of NG ROADMs Technology building blocks of NG ROADMs • Route and Select architecture • Wavelength Switched Optical Network • Benefits of NG ROADMs Conclusion Acknowledgement References
- 3. Introduction ROADMs are evolving to support market demands for increasing bandwidth and enhanced flexible wavelength routing. The trend towards dynamic capacity allocation demands ROADMs to be- Colorless, Directionless, Contentionless and Gridless. ROADM evolution from 2-degree fixed wavelength add-drop to present >= 8 degree CDC add-drop architecture. Next-generation solution that offers true network agility has put ROADM at the forefront of the race to stay ahead of the traffic explosion.
- 4. Overview on ROADM Fujitsu was the first vendor to develop and deploy ROADM technology in 2003 and the first to incorporate a WSS-based optical switch fabric. ROADM (Reconfigurable Optical Add Drop Multiplexer) is an optical network element which is able to Add/Drop or Pass through any wavelength. ROADM along with optical amplifiers, multiplexer-demultiplexer, transponder or/and muxponder cards constitutes a complete, flexible, optical transport node. All optical subsystem which enables remote configuration of wavelengths at any time. Technologies used- Wavelength blocking, Planar Lightwave Circuit (PLC), Wavelength Selective Switch (WSS). FIXED RECONFIGURABLE MANUAL INTERVENTION AUTOMATED
- 5. Operational Benefits: Operational Simplicity Remotely configurable. Per wavelength SW provisioning and management. Simple cabling. Faster Deployment No re-engineering when capacity is exceeded as in fixed OADM. Increased Reliability Network requires fewer manual touches. Software configuration reduces erroneous cabling errors. De- Mux Mux Mux Optical Space Switch De- mux A D M
- 7. Flexible Optical Networks WSS based ROADMs have been deployed widely in networks through out the world –they are functionally efficient but not flexible. Flexibility is required to move towards next phase of optical switching. First generation ROADMs architectures are limited by: -Fixed wavelength assignments to specific ports. -Fixed direction assignments for multiplexers (i.e. North only, South only…) -Partitioned add/drop structures due to wavelength contention conflicts. Need for NEXT GENERATION ROADMs …
- 8. Functionality requirements of NG ROADMs COLORLESS or COLOR INDEPENDENT functionality DIRECTIONLESS or DIRECTION INDEPENDENT functionality CONTENTIONLESS or WAVELENGTH CONTENTION FREE functionality GRIDLESS or FLEXIBLE ITU GRID functionality
- 9. High-Level NG ROADM Requirements 1 Multi-degree ROADM N = 8-16 for Metro N = 6-8 for Long Haul 9.6 Tb capacity per fiber Flexible bandwidth allocation Future proof express path High level of integration Advanced Automation Supervision and Monitoring Degree Degree Degree Degree Degree Degree CDC Transponder Pools 3 N N 4 2 Current Transponder Pools support 40G/100G (coherent) Colorless Directionless Contentionless
- 10. Directed V/s Directionless ROADM •Fixed add/drop ports for particular direction •Change in direction requires physical rewiring by technician Figure : 3rd degree ROADM with directed architecture If Node fails?
- 11. ROADM West ROADM East Directional ROADM Line West Line East Add/Drop West Add/Drop East ROADM West ROADM East Directionless ROADM NxN Switch FabricNxN Switch FabricNxN Switch Fabric In directional ROADM recabling of transponders needed. In directionless ROADM , no recabling is needed
- 12. Colored V/s Colourless ROADM Colored access ports imply that physical access ports (add or drop) are assigned to a specific wavelength. Physically change the fiber connectivity between the transceiver and access ports to change wavelength. No dynamic wavelength change. In colorless architecture, without changing port the color of the wavelength can be reconfigured. No recabling needed. ROADM West ROADM East Colourless ROADM
- 13. Contentionless ROADMs Even with colorless and directionless functionality, the ROADM network is still limited by the total number of flexible CD add/drop ports available. If two wavelengths of same color converge at same add/drop port of WSS - Leads to Wavelength blocking /wavelength contention! Solution- Replace CD mux/demux units with new set of add/drop units called Contentionless add/drop units (n X m unit instead of 1 X n /n X 1)
- 14. What is Contentionless Add/Drop ? ROAD M R X T X R X T X Contention-less – In the same Add/Drop device you can add and drop the same frequency to multiple ports. ROAD M R X T X R X T X Directionless – Wavelength can be routed from any Add/Drop port to any direction in software. ROAD M R X T X R X T X Colorless – ROADM ports are not frequency specific (re-tuned laser does not require fiber move)
- 15. Increased usage of video and online applications through new devices such as smart phones and tablets- demands more BANDWIDTH Need for faster network and higher optical performance. Pressure on optical networks! Insufficient bandwidth! SOLUTION ?
- 16. 1) Increase number of channels :80 96 100 150 More channels= more spectrum space. But problem of physics! 2) Allocate bandwidth flexibly instead of 50GHz Not a standard! 3) Signal shaping- DSP in transmitters of transponder - OFDM - Nyquist filtering Gridless or Flexible GRID
- 17. Capacity Enhancements in DWDM Networks … Legacy networks as deployed today: 50 GHz, fixed grid 40G 40G 40G 40G 10G 10G 10G 100G 50GHz Spectraloccupancy 1T … 50GHz 200GHz , nm 100G 400G 1T 200G 100GHz Spectraloccupancy 50GHz Future networks: 50-200 GHz, flexible grid , nm
- 19. Flex Spectrum DWDM Architecture Ch1 Ch2 Ch3 Ch4 DSP-Enabled Transmitters Flex Spectrum ROADM Signal Shaping TX1 TX 2 TX 3 TX 4 Ch1 Ch2 Ch3 Ch4 FlexSpectrum DWDM system Optical multiplexer Denser Channel Spacing
- 21. Flexible Grid/Gridless implies a more granular version of the spectrum usage, down to 12.5GHz (ITUT G.694.1) Hence, ROADM nodes supporting a flexible grid could operate at any speed that is based on increments of 12.5GHz spacing. This ensures optimum and wise usage of spectrum. Moreover, it opens a gate for dynamic allocation and usage of the ITU Grid. Isn’t it AMAZING!
- 22. Technology building blocks of NG ROADMs •Wavelength selective switch (WSS) is the heart of current generation ROADM networks also for the NG networks. •CDC ROADM is nothing but N X M WSS capable of switching wavelength from multiple input port to several output port. 2003 WSS Year of deployment 2 x 1 2003 9 x 1 2007 16 x 1 2012 20x1 2013
- 24. Broadcast Mesh Patch Panel Legacy ROADM – Broadcast & Select • Ingress channels from each degree are passively split (broadcast) to all other degrees (plus the per-degree add/drop) • Mux WSS blocks all channels not intended for that degree (selects those that are) • Channel isolation becomes difficult as the number of degrees increases (creates large penalty for 16 QAM channels) • directionless add/drop consumes an available degree; Colorless requires add/drop WSS ( using a larger split ratio on the ingress not practical from a network OSNR requirement) WSS ‘Select’ WSS ‘Select’ WSS ‘Select’ Per Degree Add/Drop Per Degree Add/Drop Per Degree Add/Drop DegreeA Degree B DegreeC “Broadcast and Select” Architecture
- 25. Routed Full Mesh Patch Panel ROADM – Route & Select • Demux WSS ‘routes’ any combination of waves from COM-RX to any output port (drop and other degrees) • Mux WSS ‘selects’ any combination of waves from its input ports (add and other degrees) to COM-TX • Channels are isolated by both the ingress and egress WSS, improving performance • By eliminating the splitter, insertion loss is reduced, preserving channel OSNR • Enables directionless and colorless at large scale Add Structure Drop Structure WSS ‘Select’ WSS ‘Route’ WSS ‘Select’ WSS ‘Route’ WSS ‘Select’ WSS ‘Route’ DegreeA Degree B DegreeC “Route and Select” Architecture
- 26. WSON WSON (wavelength swithed optical network) is a standards based GMPLS control plane which imparts intelligence to the optical layer. Two types of control plane are prominent : Peer type and overlay type. WSON is an overlay based control plane. Control plane can be centralised or distributed.
- 27. Looking ahead for – Agile Optical Layer! NCS 2000 Embedded Optical Intelligence Tunable Laser Colorless Tunable ReceiverDirectionless Contention-less Gridless WSON Wavelength Switched Optical Network Complete Control in Software, No Physical Intervention Required
- 29. Benefits of NG ROADMs Wavelength and Route flexibility (with CDC architecture) Automatic wavelength restoration Load balancing as network and traffic evolves Support for datarates beyond 100Gb/s Fully automated link provisioning
- 30. ROADM market Ref: Dupont Photonics Technologies
- 31. CONCLUSION Next-generation ROADM devices prepares service providers to meet today’s traffic needs and the needs of tomorrow. “Gridless” or flex spectrum enables mixed channel plans adjustable in software to accommodate a mix of today’s modulation as well as future modulations.
- 32. ACKNOWLEDGEMENT: Firstly, we would like to thank Prof. Dr. Chen for giving us an opportunity to share a gist of our knowledge in next generation optical networks. Also , we thank our friends and colleagues for their immense support and co-operation for making this presentation successful.
- 33. REFERENCES: M.A.F. Roelens, D. Williams, J. Bolger and B.J. Eggleton “Advanced applications of flexible ROADM technology PhotonicsGlobal@Singapore, (2008). IPGC 2008. IEEE 10.1109/IPGC.2008.4781453. “ New Devices Enabling Software Defined Optical Networks”, Brandon Collings from JDSU.IEEE Communications Magazine • March 2013. “The ROADM to smarter Optical Networking”, George Lawton, Computing Now Exclusive Content — July 2010 . “Benefits and Requirements of Flexible Grid ROADM’s and networks” by Sheryl L Woodward and Mark.D. Feuer.VOL. 5, NO. 10/OCTOBER 2013/J. OPT. COMMUN. NETW. S. Gringeri, B. Basch, V. Shukla, R. Egorov, and T. J. Xia,“Flexible architectures for optical transport nodes and networks,” IEEE Commun. Mag., vol. 48, no. 7, pp. 40–50, July 2010.
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