A provably good wavelength-division-multiplexing-aware clustering algorithm for on-chip optical routing

As the VLSI technology continues to scale down, combined with increasing demands for large bandwidth and low-power consumption, the optical interconnections with Wavelength Division Multiplexing (WDM) become an attractive alternative for on-chip signal transmission. Previous WDM-aware optical routing works consist of two main drawbacks: they are based mainly on heuristics or restricted integer linear programming to handle optical routing, and the addressed types of transmission loss and WDM overheads are incomplete. As a result, no performance guarantees can be achieved on their WDM clustering results, and/or their computations are too time-consuming. To remedy these disadvantages, we present a polynomial-time provably good WDM-aware clustering algorithm and a new WDM-aware optical routing flow to minimize the transmission loss and the WDM overheads with a significant speedup. The proposed WDM-aware clustering algorithm guarantees to find an optimal solution for 1-, 2-, and 3-path clustering, and has the constant performance bound 3 for most cases of 4-path clustering. Experimental results based on the ISPD 2007 and 2019 contest benchmarks and a real optical design show that our optical router significantly outperforms published works in wirelength, transmission loss, wavelength power, and runtimes.