Abstract

Optical networks-on-chip (ONoCs) represent an emerging technology for use as a communication platform for systems-on-chip (SoC). It is a novel on-chip communication system where information is transmitted in the form of light, as opposed to conventional electrical networks-on-chip (ENoC). As the ONoC becomes a candidate solution for the communication infrastructure of the SoC, the development of proper hierarchical models and tools for its design and analysis, specific to its heterogeneous nature, becomes a necessity. This chapter studies a class of ONoCs that employ a single central passive-type optical router using wavelength division multiplexing (WDM) as a routing mechanism. A novel protocol stack architecture for the ONoC is presented. The proposed protocol stack is a 4-layered hardware stack consisting of the physical layer, the physical-adapter layer, the data link layer, and the network layer. It allows the modular design of each ONoC building block, thus boosting the interoperability and design reuse of the ONoC. Adapting this protocol stack architecture, this chapter introduces the micro-architecture of a new router called electrical distributed router (EDR) as a wrapper for the ONoC. Then, the performance of the ONoC layered architecture has been evaluated both at system-level (network latency and throughput) and at the physical (optical) level. Experimental results prove the scalability of the ONoC and demonstrate that the ONoC is able to deliver a comparable bandwidth or even better (in large network sizes) to the ENoC. The proposed protocol stack has been modeled and integrated inside an industrial simulation environment (ST OCCS GenKit) using an industrial standard (VSTNoC) protocol.