Wire cost and communication analysis of self-assembled interconnect models for networks-on-chip

Building complex interconnect networks in a bottom-up way, for example by using self-assembling techniques, represents an ultimate challenge for building large-scale emerging computing devices. Due do the general lack of precise control over many self-assembling techniques, such interconnects are expected to be largely unstructured. In this paper we introduce two simple wire growth models for non-classical self-assembled network topologies. The models generate different unstructured and physically plausible network topologies. We then investigate the design trade-offs of such interconnect networks within a network-on-chip (NoC) simulation framework. In particular, we analyze the network's wiring cost and the communication properties by varying the framework's parameters. Our primary goal is to (1) investigate and understand the characteristics of such self-assembled networks and (2) to ultimately use these insights to tune experimental self-assembly process parameters. The quantitative simulation results show that unstructured NoC topologies obtained by the growth models show specific wire-length distributions that are beneficial for the communication and minimize the wiring cost. To support this result, we have also used an evolutionary optimization framework for the evolution of NoC topologies under given cost and communication requirements. Our results and the evaluation framework have implications for the design of interconnect architectures.