Best fit (BF): A new Spectrum Allocation mechanism in Elastic Optical Networks (EONs)

Routing and spectrum allocation (RSA) is known as a key challenge in elastic optical networks (EON). Specifically, RSA process is categorized as (i) without adjusting modulation format (simply referred to as RSA), and (ii) with adjusting modulation format (referred as routing, modulation level and spectrum allocation (RMSA)). This paper focuses on the former, that is RSA problem which is basically subdivided into two subproblems, (i) routing subproblem, and (ii) spectrum allocation. Up until now, various routing algorithms and different spectrum allocation mechanisms have been introduced by the research community. Nevertheless, we have proposed a new SA mechanism referred to as best fit (BF) with the aim of reducing the blocking rate by means of efficiently assigning the network resources. In particular, the proposed BF tries to assign a slot block (SB) to each connection such that the difference between the SB length and connection length becomes minimum. In order to further improve the performance of the BF, we have developed an optimization framework called optimized BF (Opt BF). Numerical results confirm the fact that the proposed BF outperforms the conventional mechanisms in terms of blocking probability. Moreover, it is verified that the Opt BF successfully alleviates the blocking probability even more, and assigns the networks resources efficiently.