Exploiting Implementation Diversity and Partial Connection of Routers in Application-Specific Network-on-Chip Topology Synthesis

This paper proposes a novel application-specific Network-on-Chip (NoC) topology synthesis method, in which the partial connection and the implementation diversity of routers are exploited. NoC has emerged as a promising solution to future system-on-chip (SoC), and many researchers have focused on the automatic synthesis of NoC topology. In our observation, those NoC topology synthesis methods resemble the logic synthesis in the following sense: both the NoC topology synthesis and the logic synthesis determine the connections among the components where the components are the routers in the former and the logic cells in the latter. However, an outstanding difference is that the existing NoC topology synthesis methods consider only a single implementation for each size of router, whereas modern logic synthesis tools utilize multiple implementations of a cell to produce better netlist by the feature called technology mapping. To tackle this drawback, we propose a novel NoC topology synthesis methodology where the implementation diversity of routers is exploited to produce optimal topologies in terms of area and/or power consumption. Two different approaches, the post-process approach and the in-process approach, are proposed for exploiting the implementation diversity to provide flexibility between synthesis time and design quality. Also, the proposed method for characterizing and modeling routers makes it feasible to consider the implementation diversity even when the partial connection of routers is considered during the synthesis. Compared to the method in which the implementation diversity is exploited but the partial connection is not, the experimental results demonstrate that the proposed method can reduce the power consumption by up to 67.8% and 40.0% on average. On the other hand, compared to the method in which the partial connection is exploited but the implementation diversity is not, the power consumption is reduced by up to 12.0% and 3.4% on average.