Comparing Energy and Latency of Asynchronous and Synchronous NoCs for Embedded SoCs

Power consumption of on-chip interconnects is a primary concern for many embedded system-on-chip (SoC) applications. In this paper, we compare energy and performance characteristics of asynchronous (clockless) and synchronous network-on-chip implementations, optimized for a number of SoC designs. We adapted the COSI-2.0 framework with ORION 2.0 router and wire models for synchronous network generation. Our own tool, ANetGen, specifies the asynchronous network by determining the topology with simulated-annealing and router locations with force-directed placement. It uses energy and delay models from our 65 nm bundled-data router design. SystemC simulations varied traffic burstiness using the self-similar b-model. Results show that the asynchronous network provided lower median and maximum message latency, especially under bursty traffic, and used far less router energy with a slight overhead for the inter-router wires.