Holding-time-aware spectrum allocation algorithm for elastic optical networks

The spectrum fragmentation will impact the spectral utilization significantly in dynamic spectrum allocation (SA) over elastic optical networks (EONs). To reduce fragmentation, SA algorithm should sufficiently consider various factors so as to achieve optimization. In this paper we focus on the SA issue in dynamic scenario with holding time awareness in EONs. Firstly, a novel metric, considering the fragmentation impact from the perspectives of occupied frequency slots (FSs) and free FSs jointly, is designed to measure fragmentation in a path. Benefiting from the metric, a holding-time-aware algorithm is proposed, which considers different overall fragmentation states in the network to select the optimal approach to allocate spectrum. We examine the performance of the proposed algorithm through simulations, and the results indicate that the proposed algorithm obtains lower blocking probabilities and is able to make more use of network resource compared with traditional algorithms.