MLRW: Minimal Link-usage Routing and Reusable Wavelength Assignment for Multiple Multicasts in Ring-based Optical Network-on-Chip

With the development of on-chip optical transmission technology, Optical Network-on-Chip (ONoC) is promising to meet the requirements of high throughput and low transmission latency for the on-chip communication. Multicast communication is one of the most common communication patterns in cache coherence protocols and various parallel applications for ONoC. However, traditional multicast strategies cannot effectively utilize the limited number of wavelengths in ONoC and only consider one multicast. In this paper, we propose a Minimal Link-usage routing and Reusable Wavelength assignment scheme for multiple multicasts in ring-based ONoC (called MLRW), with the objective of minimizing the number of wavelengths used. Specifically, we formulate the routing and wavelength assignment problem for multiple multicasts in a ring-based ONoC into a 0-1 Integer Programming (IP) optimisation model at first. Then, a minimal link-usage routing is proposed to reduce the number of links by each multicast. Based on it, we introduce a reusable wavelength assignment approach that designates a particular wavelength for each optical routing path, aiming to minimize the total number of wavelengths needed. Finally, the simulation results demonstrate that our method achieves a reduction of 28.6% in the average number of wavelengths used compared to alternative approaches in the ring-based ONoC, with lower routing complexity, freedom from deadlock, and strong scalability.