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NFV-Enabled optimal spectrum allocation in flex-grid optical networks

Abstract:

This paper proposes an NFV-Enabled optimal spectrum allocation solution applicable to fixed-grid and flex-grid wavelength division multiplexing (WDM) optical networks. By exploiting the frequency shifting capability of individual lightpaths, the proposed approach aims to recalculate the initial spectrum allocation to eliminate the unusable gaps between occupied frequency slots. The reorganized spectrum will facilitate the allocation of new connections, in order to enable the maximization of spectrum utilization. In this regard, this paper describes the NFV-enabled scheme for carrying out the optimal spectrum allocation. The optimization problem is formulated as an Integer Linear Program (ILP) model and solved optimally using an exact brute-force search-based algorithmic strategy (OptFs). Given the NP-hard nature of the optimization problem and the non-polynomial complexity of OptFs, a suboptimal, faster heuristic strategy (FastFs), based on a prepartition method, is proposed. Simulation results validate the performance of the proposed optimal spectrum allocation approach, and the exact and heuristic solutions, compared to the non-application of strategies, demonstrate improvements in spectrum utilization while offering a dynamic network operation.