Routing and Spectrum Allocation in Spectrum-Sliced Elastic Optical Path Networks

Recently, the OFDM-based Spectrum-sliced Elastic Optical Path (SLICE) network attracts significant interests due to its elastic band-width allocation. The OFDM technology, on one hand, enables both sub-wavelength and super-wavelength traffic accommodation by allocating appropriate number of sub-carriers. On the other hand, it can provide high signal quality by overcoming various impairments. In SLICE networks, one fundamental problem is to establish spectrum paths by allocating sub-carriers along the corresponding route to accommodate traffic demands. This is referred to as the routing and spectrum allocation (RSA) problem. The optimal RSA problem is NP-Hard and different from the traditional routing and wavelength assignment (RWA) problem in WDM networks. In this work, we formulate the RSA problem using the Integer Linear Programming (ILP) formulations to achieve different optimization objectives. We then analyze the lower/upper bounds for the sub-carrier number in a SLICE network. We also propose two efficient heuristic algorithms to minimize the required sub-carrier number in a large SLICE network when the ILP model becomes intractable. The results show that the proposed algorithms can match the analysis and approximate the optimal solutions from the ILP model.