Lightpath threshold adaptation algorithm for dispersion-adaptive first-last fit spectrum allocation scheme in elastic optical networks

This paper proposes a lightpath threshold adaptation algorithm for dispersion-adaptive first-last fit spectrum allocation scheme in elastic optical networks in order to improve the performance in terms of call blocking in the network. The proposed algorithm adapts the suitable lightpath threshold value, denoted by β, according to the traffic condition in the network. The dispersion-adaptive first-last fit spectrum allocation scheme assigns longer lightpath requests from the smallest indexed spectrum slot, where the dispersion effect is less, and shorter lightpath requests from the largest indexed spectrum slot, where the dispersion effect is more. As a result, a less robust modulation technique is used to maintain the QoT threshold level for the longer lightpath requests, and hence a lower number of spectrum slots are required for lightpath establishment. Simulation results show that the dispersion-adaptive first-last fit spectrum allocation scheme is effective with incorporation of the proposed lightpath threshold algorithm when traffic condition changes in the network.