A Hierarchical Optical Network-On-Chip Using Central-Controlled Subnet and Wavelength Assignment

Optical network-on-chip (ONoC) is a promising alternative to be served as the fundamental architecture for future many-core system. However, several problems of ONoC, such as power consumption, arbitration overhead, and device cost, pose many limitations to the architecture design. In this paper, a novel hierarchical ONoC structure named CWNoC is proposed, which is a 256-core architecture composed of multiple central-controlled subnets. It reduces the network complexity by dividing the whole network into several subnets and lowers the arbitration overhead by adopting centralized arbitration logic in each subnet. An efficient wavelength assignment method, making full use of broadband microring resonators, is also employed in CWNoC, which facilitates simplifying the optical layer and reducing the possibility of contention. The simulation results show that CWNoC has a better latency and power consumption performance. For example, when low and medium load is applied, the latency reduction can be as much as 40 ns compared with WANoC, while the total power consumption is reduced by 70%.