A subcarrier-slot partition scheme for wavelength assignment in elastic optical networks

In elastic optical networks (EONs), bandwidth fragmentation refers to the existence of non-aligned and noncontiguous subcarrier slots (unused) in the set of all subcarrier slots. Since wavelengths for a connection must be allocated on contiguous subcarrier slots, these non-aligned and noncontiguous available subcarrier slots could cause bandwidth blocking. This paper proposes a subcarrier-slot partition scheme for wavelength assignment in EONs that can yield more contiguous aligned available subcarrier slots, which reduces the bandwidth blocking probability. On this scheme, the total set of subcarrier slots is separated into several partitions and wavelengths are assigned to each partition based on the links utilized by particular connections. Numerical results from a simulation show that the proposed scheme with a suitable wavelength assignment policy outperforms the conventional scheme in terms of bandwidth blocking. We investigate the effect of different wavelength assignment policies in the proposed scheme. The results show that the first-last fit assignment policy gives lower bandwidth blocking probability than the first fit assignment policy.