Selection of spectral-spatial channels in SDM flexgrid optical networks

Space division multiplexing (SDM) is a promising solution with the scaling potential to overcome the possible capacity crunch problem in optical backbone networks. The key idea behind SDM is to exploit the spatial dimension to provide a significant increase in the transmission system capacity. In SDM, optical signals are transmitted in parallel through spatial resources (fibers, cores or modes), thus co-propagating in the same optical fiber structure. The goal of this paper is twofold. First, we propose and evaluate several versions of a greedy algorithm for optimization of flexible-grid SDM optical networks, including comparison with optimization results yielded by the CPLEX solver. Second, using best found algorithm settings, we complement our study with an analysis of SDM network performance in terms of the spectrum usage. We report and discuss results of numerical experiments run on a representative network topology with realistic physical assumptions. The key observation is the low scalability of the CPLEX solver, while the greedy algorithm is capable of generating solutions for larger network scenarios. However, even the relatively simple heuristic experiences quite large execution times.