CPNoC: An Energy-Efficient Photonic Network-on-Chip

Now energy efficiency is becoming the most critical design facet for the scaling of Network-on-Chip (NoC). Different with electronic network, photonic Network-on-Chip offers natural solutions to reduce energy consumption. In this paper, we propose an energy-efficient photonic Network-on-Chip with central controller (CPNoC). Our proposed on-chip network utilizes a hybrid architecture, comprised of an optical transmission network and an electronic control network. The most important feature of our proposed network is that electronic network uses just one central controller to process and forward control messages. Thus these control messages will not suffer from high hop count to reach destination node. Central controller holds a photonic switching element (PSE) state table and controls all PSEs' switch on/off. When a new control message arrives, it sets up or tears down an optical link quickly, according to the information carried by the message. Finally, we evaluate and compare the energy efficiency and average transmission latency for 16-/64-core electronic NoC, photonic mesh NoC and CPNoC under various packet sizes. The results show that on average our proposed network can reduce at least half of network energy consumption, while keeping lower transmission latency.