CustomTopo: A Topology Generation Method for Application-Specific Wavelength-Routed Optical NoCs

Optical network-on-chip (NoC) is a promising platform beyond electronic NoCs. In particular, wavelength-routed optical network-on-chip (WRONoC) is renowned for its high bandwidth and ultra-low signal delay. Current WRONoC topology generation approaches focus on full-connectivity, i.e. all masters are connected to all slaves. This assumption leads to wasted resources for application-specific designs. In this work, we propose CustomTopo: a general solution to the topology generation problem on WRONoCs that supports customized connectivity. CustomTopo models the topology structure and its communication behavior as an integer-linear-programming (ILP) problem, with an adjustable optimization target considering the number of add-drop filters (ADFs), the number of wavelengths, and insertion loss. The time for solving the ILP problem in general positively correlates with the network communication densities. Experimental results show that CustomTopo is applicable for various communication requirements, and the resulting customized topology enables a remarkable reduction in both resource usage and insertion loss.