Tipping point for the future scalable OXC: what size MxM WSS is needed?

We propose a highly scalable and compact optical-node architecture that combines the subsystemmodular optical cross-connect (OXC) and transponderbank add/drop, where multiple M × M wavelength-selective switches are effectively introduced. Numerical experiments verify that the proposed architecture offers large-scale nodes with substantially relaxed hardware requirements while holding the fiber-utilization offset to a minimal level.