Fast scheduling based on iterative parallel wavelength matching for a multi-wavelength ring network-on-chip

In synchronous networks-on-chip (NoC), scheduling of packet transmission is required for achieving high throughput, low latency and good fairness, while avoiding packet collisions. Efficient algorithms exist for rearrangeably non-blocking NoC. However, when realized with integrated optical devices, NoC are typically arranged in topologies that are blocking if a single wavelength is used. Mitigation of the blocking behavior is then achieved by exploiting the wavelength domain, which requires however a novel scheduling paradigm. This paper presents an integrated optical NoC based on a ring topology and realized with multiple resonating microrings (MMR). Scheduling in MMR architecture comprises the conventional matching sub-problem along with wavelength assignment sub-problem, which accounts for the additional constraints due to the wavelength domain. A novel scheduling algorithm based on iSLIP algorithm is proposed for jointly addressing both sub-problems. The iterative Parallel Wavelength Matching (iPWM) algorithm achieves performance similar to a two-step scheduler based on sequential iSLIP and first-fit wavelength assignment, but with a computational complexity lower and independent of the number of wavelengths.