Greenfield Gradual Migration Planning toward Spectrally-Spatially Flexible Optical Networks

This article identifies the unavoidably required upgrade of short-term realizable elastic optical networks(EONs) operating over single-mode fibers toward spectrally-spatially flexible optical networks(SS-FONs), exploiting spatial division multiplexing (SDM) technology in order to cope with the expected mid- and long-term future traffic forecasts. Since a complete EON to SS-FON network migration overnight is unrealistic, this article proposes a gradual greenfield migration strategy employing novel heuristic planning solutions. These solutions allow identifying which network components should be SDM-capable so as to support the forecasted traffic increase at a given time. To allow transmission in an SS-FON, links should be extended with SDM-capable fibers and nodes should be equipped with SDM-capable reconfigurable optical add/drop multiplexers. Using the proposed solutions, a migration case study in a national reference core networkis provided and analyzed.