Design of an Energy-Efficient Asynchronous NoC and Its Optimization Tools for Heterogeneous SoCs

Abstract

The energy usage of on-chip interconnects is a concern for many system-on-chips targeting portable battery-powered devices. We have designed and evaluated a network-on-chip (NoC) for such an application, including tools to optimize for power and communication latency. Our asynchronous (clockless) network operates with efficient two-phase bundled-data links and four-phase routers. The topology and router floorplan is determined by our tool, ANetGen, which optimizes the network for energy and latency using simulated annealing and force-directed placement methods. We compare our solutions against a traditional synchronous NoC as specified by the COSI-2.0 framework and ORION 2.0 router and wire energy models. Traffic is simulated with SystemC functional models, and messages are generated with a “bursty” self-similar <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">b</i> -model. Results indicate our asynchronous network was more energy-efficient, lower in area, and provided comparable or superior message latency.