Leveraging Spectrum Sharing and Defragmentation to $p$ -Cycle Design in Elastic Optical Networks

In this letter, a new protection technique, namely Spectrum Shared pre-configured cycles (SS-p-cycles), is proposed for survivable elastic optical networks. SS-p-cycles permit to cut spectrum usage and spectrum fragmentation ratio (SFR) by leveraging special spectrum sharing among multiple p-cycles that have common link(s). To compute SS-p-cycles, we first formulate an integer linear programming model to obtain the optimal solution in small instance, and then develop a time-efficient heuristic algorithm to solve large-scale instances. Simulation results have demonstrated that the proposed SS-p-cycles outperform conventional p-cycles without spectrum sharing in terms of spectrum usage and SFR.