Elastic Spectrum Allocation for Time-Varying Traffic in FlexGrid Optical Networks

Abstract

Elastic flexgrid optical networks (FG-ON) are considered a very promising solution for next-generation optical networks. In this article we focus on lightpath adaptation under variable traffic demands in FG-ON. Specifically, we explore the elastic spectrum allocation (SA) capability of FG-ON and, in this context, we study the effectiveness of three alternative SA schemes in terms of the network performance. To this end, we formulate a Multi-Hour Routing and Spectrum Allocation (MH-RSA) optimization problem and solve it by means of both Integer Linear Programming (ILP) and efficient heuristic algorithms. Since, as numerical results show, the effectiveness of SA schemes highly depends on the traffic demand profile, we formulate some indications on the applicability of elastic SA in FG-ON.

Multi- Spectrum Bands Allocation for Time-Varying Traffic in the Flexible Optical Network

“…The spectrum allocation to time-varying traffic connections as indicated by several studies [10,12] is an ILP optimization problem. It is also known to be np-hard when the network size increases.…”

“…The first studies of spectrum resources allocation to time-varying traffic connections deals with the methods of expansion/contraction of frequency slots, based on the constraint that two adjacent connections must not use the same frequency slots simultaneously in the same time slot. In this way, the paper [12] provides three policies of spectrum expansion/contraction depending on the fluctuation in traffic. These policies differ from one to other by the limitations suffered by the reference frequency and the allocated spectrum band width.…”

“…So, this problem is np-hard. When the network size grows the time to find an optimal solution also grows exponentially as several studies have already shown it [2,11,12]. In that condition, the suitable heuristic can be used to obtain near optimal solution within a reasonable time.…”

Solving Large Instances of the RSA Problem in Flexgrid Elastic Optical Networks

“…The use of advanced transmission and modulation techniques, spectrum-selective switching technologies, and flexible frequency grids (flexgrids), will allow next-generation optical networks to be spectrally efficient and, in terms of optical bandwidth provisioning, scalable and elastic [2], [3], [4]. Among key concepts implemented in flexgrid elastic optical networks (EONs) we can distinguish distance-adaptive modulation format assignment [5] and multi-carrier (i.e., superchannel, abbreviated as SCh) transmission [6].…”

“…In the literature, mixed-integer programming (MIP) formulations (e.g., [7], [8], [10]), metaheuristics (e.g., [3], [11], [12]), and heuristics (e.g., [8], [13]), have been proposed to solve RSA. (Meta)heuristics can produce locally optimal solutions, however, without guarantees for global optimality.…”