Space-Frequency Joint Contention Scheduling Algorithm Based on AoD in SDM-EONs

Compared with elastic optical networks, spectrum contention problem may become more serious in space-division multiplexing elastic optical networks. Spectrum converters (SCs) can effectively resolve the problem of spectrum contention without additional delays, but SCs have the disadvantages of complicated technologies and high costs. To resolve the two problems aforesaid, taking into account the alleviated spectrum continuity constraint caused by the space dimension and the node flexibility introduced by architecture on demand (AoD), a space-frequency joint contention scheduling algorithm (SFJSA) based on AoD is proposed in this paper. SFJSA divides the contention scheduling process into two phases: scheduling in space domain and in frequency domain. It gives priority to resolve contention in the spatial domain, and then considers using spectrum converters in spectrum domain. In the stage of space switching, a weight formula is designed to balance the costs of spectrum selective switches and the loads of cores. In the stage of spectrum conversion, a concept of spectrum compactness is introduced to further optimize the utilization of spectrum resources and spectrum converters. The simulation results indicate that the proposed algorithm can reduce the number of spectrum converters required while improving the blocking performance, which means it achieves better blocking performance in a more cost-effective manner.