Routing, spectrum, and core assignment in SDM-EONS with MCF: node-arc ILP/MILP methods and an efficient XT-aware heuristic algorithm

In this paper, we focus on the static routing, spectrum, and core assignment (RSCA) problem in spacedivision multiplexing (SDM)-based elastic optical networks (EONs) with multi-core fiber (MCF). In RSCA problems, it is a challenging task to control the inter-core interference, called inter-core crosstalk (XT), within an acceptable level and simultaneously maximize the spectrum utilization. We first consider XT in a worst interference scenario (i.e., XTunaware), which can simplify the RSCA problem. In this scenario, we formulate the RSCA problem using a nodearc- based integer linear programming (ILP) method in which the numbers of both variables and constraints are greatly reduced compared with previous ILP methods, thereby leading to a significant improvement in convergence efficiency. Then, we consider the XT strictly (i.e., XT-aware) and formulate the problem using a mixed integer linear programming (MILP) method, which is an extension of the above node-arc-based ILP method. It is more suitable for different XT thresholds and/or geographically large networks, in that it has a higher degree of generalizability. Finally, we propose an XT-aware-based heuristic algorithm. The simulation results demonstrate that our heuristic algorithm achieves higher spectrum efficiency, higher degree of generalizability, and higher computational efficiency than the existing heuristic algorithm(s).