Fragmentation-aware spectrum assignment strategies for elastic optical networks with static operation

One of the main problems in the design of elastic optical networks is the Routing, Modulation-Level, and Spectrum Assignment problem (RMLSA). In this work, we propose new strategies to solve the spectrum assignment (SA) sub-problem for EONs architectures with static network operation. To this end, we developed two new approaches called Sliding-Fit (SF) and Parcel-Fit (PF), focused on minimizing the spectrum fragmentation obtained when attending network demands. These strategies change to standard paradigm use to search an amount of consecutive FSUs for a given user by choosing a subset of FSUs in the frequency spectrum and later finding users for the selected FSUs. Additionally, the method relies on a physical-later impairment (PLI) model to compute the maximum optical reach and bandwidth demands based on the modulation level - bitrate pair.Experimental results showed that the proposed algorithms obtain less spectrum fragmentation than the best found in the literature, allowing to assign a higher number of users, decreasing the network capacity or increasing the efficiency in the use of resources.