Performance Analysis And Optimization Of Torus Network Based On Crosstalk Characteristics

With the CMOS integrated technology goes into ultra-deep submicron and nanometer era, the feature size of the chip is getting smaller and smaller, and the increasingly complex functionalities need to be achieved in a single chip. However,traditional architecture and interconnect technology have some bottlenecks in bandwidth,latency, and power dissipation, and so on, which lead to it cannot meet the requirement of the system-on-chip(SoC). Network-on-chip(NoC) is a new scheme for solving the interconnection problem and communication requirements among the multi-processors of SoC, now the most common scheme is employing hybrid interconnection structure, in which the optical network is used for high-speed data transmission and electric network is designed for controlling the transmission of the optical network layer. Currently, most research of the NoC is mainly concentrated on the design and optimization of photonic device, routers, and network topology structure, in addition, the performance evaluation focuses on the analysis of energy consumption, throughput, and delay. Optical network-on-chip(ONoC) is a network composed of various silicon-based waveguide devices, however, crosstalk is the inherent attribute of the devices and the crosstalk cumulant in optical network restricts the performance improvement, so the crosstalk is a core problem studied in this paper. The preliminary analysis for crosstalk issue of the optical network is mainly focused on traditional structure. Furthermore, the change of the crossing angle of crosswise waveguide in basic photonic device will introduce different crosstalk noise and insertion loss. Instead of using fixed vertical crossing structure inoptical router and network, the optimal crossing structure used in the paper can well control the crosstalk issue, which achieves to improve performance and lays the theoretical foundation for expanding the network scale. In this paper, a formal theoretical analysis model and simulation model are proposed for studying the signal transmission of Torus-based ONoC, which is based mainly on crosstalk characteristics analysis and provides guidance for coming design of optical routers and network structure with better performance.First of all, this paper introduces the basic structure and working principle of silicon-based waveguide devices used in optical interconnection network, in which microresonator designed by straight waveguide and closed loop waveguide is a core device for achieving optical switch function, and then, the loss and crosstalk models of the crossing waveguide, parallel switching element, and crossing switching elements are discussed in detail, where the crossing angle of the crossing structure is no longer confined to the traditional vertical crossing. Next, the basic structure characteristics of Torus-based ONoC and its five port optical routers are introduced in the paper.Considering that optimized crossing angle can reduce the introduced crosstalk noise,therefore the optimized method will be extended to the router layer and network layer design. On the basis of the above-mentioned analysis, the design criteria of the optical router on chip can be summarized for low crosstalk and low loss requirement and the theoretical analysis models of the router layer and the network layer are proposed for performance study. Finally, the results obtained by numerical and simulate analysis show that the optical router structure used in optical interconnection network needs to reduce the number of microresonators and crossing structures as much as possible, on the basis of the optimized router used in optical network, angle optimization method can be further applied to router layer and network layer simultaneously, which can effectively reduce the crosstalk noise, increase the signal to noise ratio, and decrease the bit error rate, so as to ensure the communication quality and achieve the performance improvement of the system. For example, when the network scale of a torus-based ONoC is 6×6, and the input power is 0dBm, the SNR of a torus-based ONoC using the optimized structure can reach 23.87 dB, which is 2.21 dB and 9.27 dB higher than those using Crux and optimized crossbar routers, respectively. Based on the basic characteristics and simulation results of the optical device, optical router, and network layer, this paper constructs a signal analysis platform of ONoC, which can be used to study the related theory and technology solutions of photonic switching system on chip comprehensively.