Using spectrum fragmentation to better allocate time-varying connections in elastic optical networks

Elastic optical network (EON) technology arises as a promising solution for future high-speed optical transport, since it can provide superior flexibility and scalability in the spectrum allocation for seamlessly supporting diverse services, while following the rapid growth of Internet traffic. This work focuses on lightpath adaptation under time-variable traffic demands in EONs. Specifically, we explore the possibility of utilizing the spectral fragmentation to increase the spectrum allocation (SA) capabilities of EONs. In this context, a heuristic SA algorithm, which intentionally increases the spectral fragmentation in the network, is proposed and validated. In our proposal, the spectrum assigned to each new connection is in the middle of the largest free spectral void over the route, aiming to provide considerable spectral space between adjacent connections. These free spectral spaces are then used to allocate time-varying connections without requiring any lightpath reallocation. The obtained simulation results show a significant improvement in terms of network blocking probability when utilizing the proposed algorithm.