Spectrum management in heterogeneous bandwidth optical networks

As optical networks continue to evolve to support increasing bandwidth demands, lightpaths will take on different spectrum spaces as opposed to the current uniform 50-GHz grid, thereby giving rise to elastic optical networks. When lightpaths of heterogeneous bandwidths co-exist, two factors emerge that will degrade the provisioning efficiency and negatively impact its sustainable evolution: (1) unfairness of access among different bandwidth connections, and (2) spectrum fragmentation caused by bandwidth mismatch. We have devised a comprehensive metric, Fragmentation Index, to capture the essence of fragmentation. Through analysis and simulations, we show that an admission policy that differentiates different bandwidth lightpaths by spectrum partitioning achieves better provisioning efficiency by resolving these two problems.