Performance Optimization and Evaluation for Torus-Based Optical Networks-on-Chip

As a new trend, torus-based optical networks-on-chip (ONoCs), which can be considered as an extension of a 2-D network topology based on a mesh topology, can overcome the bandwidth limitation of a conventional electrical networks-on-chip. Although ONoCs have many advantages, crosstalk and insertion loss are the two main causes of the performance degradation and network scalability constraints. When traditional crossing and optical routers are used in the original torus structure, a bit error rate of 10^-9 is needed for reliable transmission for a network scale of no more than 5 × 5. To improve the performance of torus-based ONoCs and expand network scalability, an optimum crossing of 60° or 120° is applied in an optical router and network for the first time, instead of the conventional crossing fixed at 90°. Furthermore, a mathematical noise analysis model is presented, and then, used in designing an optical communication systems based on a torus-based optical interconnection network. According to the simulation results, optimized torus-based ONoCs have a better signal-to-noise ratio (SNR) for the path-setup link at a certain network scale compared to a traditional network with fixed crossing angle. For example, when the network scale of a torus-based ONoC is 6 × 6 and the input power is 0 dBm, the SNR of a torus-based ONoC using the optimized structure can reach 23.87 dB, which is 2.21 and 9.27 dB higher than those using crux and optimized crossbar routers, respectively.