A Topology-Based Spectrum Assignment Solution for Static Elastic Optical Networks With Ring Topologies

On designing elastic optical networks, one of the main tasks to be solved is to allocate enough spectrum on the users' paths to achieve communication to all network users, known as the Spectrum Assignment problem (SA). On a static network operation, the order in which the users' spectrum demands are assigned is significant. However, standard approaches do not sort them previous to the spectrum assignment process. In this work, we first sort the users to maximize the spectrum usage based on their bandwidths and path length. Then, we propose a novel topology-based spectrum allocation strategy, which takes advantage of the ring network topology. We called it Spiral Fit, consisting of assigning the frequency spectrum to the users following a spiral (or a concentric rings) order. We compare our strategy's performance and robustness with two optimization models, only in small network topologies (from 5 to 8 nodes) since optimization processes are too expensive on more significant networks. In more extensive networks, we compare the proposed method with the most referenced techniques. The results show that consistently our method obtains near-optimal results in small topologies and outperforms the heuristic solutions found in the literature in terms of network capacity (measured as a number of frequencies slot units and spectrum fragmentation).