A routing strategy for inductive-coupling based wireless 3-D NoCs by maximizing topological regularity

Inductive-coupling is a 3D integration technique that can stack more than three known-good-dies in a System-in-Package (SiP) without wire connections. To make the best use of wireless property, the 3D ICs would have a great flexibility to customize the number of processor chips, SRAM chips, and DRAM chips in a SiP after the chip fabrication. In this work, we design a deadlock-free routing protocol for such 3-D chips in which each chip has different Network-on-Chip (NoC) topologies. We classify two-surface NoC of each chip into is 2D mesh and irregular structure in order to apply the custom routing algorithm to its topology. In mesh topologies, X-Y routing is used for well traffic distribution, while Up*/Down* routing is applied for reduced path hops in irregular topologies. Evaluation results show that the average number of hop count in uniform traffic can be improved by up to 11.8%, and the average hop count in neighbor traffic can be improved up to 6.1%.