Technoeconomic analysis of spatial channel networks (SCNs): benefits from spatial bypass and spectral grooming [Invited]

Toward the forthcoming spatial division multiplexing (SDM) era, a spatial channel network (SCN) was recently proposed in which the optical layer is explicitly decoupled from the hierarchical SDM and wavelength division multiplexing (WDM) layers, and an optical node evolves into a spatial cross-connect (SXC) and wavelength cross-connect (WXC) to achieve a hierarchical optical cross-connect (HOXC). In this paper, we perform a technoeconomic analysis of SCNs comprising different HOXC architectures employing different planning policies on how the degree of spectral grooming by WXCs and spatial bypassing by SXCs in an SCN affects the total required number of spatial lanes (SLs), whose physical entity is the core in parallel single-mode fibers or a multicore fiber and the total node cost in the SCN. Toward this end, we develop a routing and SDM/WDM multilayer resource assignment (RSWA) heuristic in which spatial bypassing and spectral grooming are performed such that the required number of SLs is minimized. Using RSWA with four planning policies, i.e., express-only, express/local-hybrid (spatial-bypass-oriented), express/local-hybrid (spectral-grooming-oriented), and local-only, we compare the performance levels of a high-port-count matrix-switch-based HOXC and core selective switch (CSS) based HOXC with those of the baseline-stacked conventional WXCs as the network traffic load increases. Here, a CSS is a new type of spatial switch, which is the counterpart to a wavelength selective switch in a current WDM network. We clearly show that hierarchical spatial bypassing and spectral grooming are beneficial in terms of the required number of SLs and network-total node cost when the required number of SLs between optical nodes in an SCN is equal to or greater than roughly 10.