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Designing Transparent Flexible-Grid Optical Networks for Maximum Spectral Efficiency [Invited]

Pedro, J. M.

Journal of Optical Communications and Networking Vol. 9, Nº 4, pp. C35 - C44, April, 2017.

ISSN (print): 1943-0620
ISSN (online):

Journal Impact Factor: 1,128 (in 2010)

Digital Object Identifier: 10.1364/JOCN.9.000C35

Higher order modulation formats and spectral super-channels are key to maximize spectral efficiency in next-generation optical transport networks, thereby postponing / minimizing expensive additional fiber roll outs and reconfigurable optical add/drop multiplexer (ROADM) node upgrades. A flexible dense wavelength division multiplexed (DWDM) grid is key to efficiently accommodate media channels requiring more (or less) than 50 GHz of contiguous spectrum. Particularly, routing media channels consisting of multiple adjacent carriers enables to pack them closer together and share a single pair of guard bands of adaptive width to cope with optical filtering. This effect is maximized by giving preference to deploying media channels with more carriers. However, designing the DWDM network in such way can translate into resource overprovisioning whenever the traffic requirements between two nodes are below the (large) capacity of the most spectrally efficient media channel format that can be deployed between those nodes. This paper provides insight on how the set of media channels and the network design framework used impact the trade-off between maximizing spectral efficiency and minimizing resource overprovisioning in transparent flexible-grid optical networks. Furthermore, it discusses enabling strategies to mitigate the risk of resource overprovisioning when maximizing network spectral efficiency is the key design objective.