Large-Scale Optical Node Utilizing $M\times M$ WSSs Optimally Configured for Traffic Distribution

We propose a novel optical node architecture that fully utilizes M × M wavelength-selective switches (WSSs), where the subsystem modular architecture is adopted and the M × M WSS ports are optimally allocated to inter-node fibers and add/drop fibers in accordance with the traffic distribution. The proposed architecture can accommodate the maximum incoming (outgoing) fiber number of 60 in USNET and 50 in the pan-European network where fiber-utilization efficiency offset is less than 3% compared with the completely unrestricted node. The number of necessary M × M WSSs is reduced by up to 26% compared with the previously proposed scheme.