3D ICs can take advantage of a scalable communication platform, commonly referred to as the Networks-on-Chip (NoC). In the basic form of 3D-NoC, all routers are vertically connected. Partially connected 3D-NoC has emerged because of physical limitations of using vertical links. Routing is of great importance in such partially connected architectures. A high-performance, fault-tolerant and adaptive routing strategy with respect to the communication flow among the cores is crucial while freedom from livelock and deadlock has to be guaranteed. In this paper we introduce a new routing algorithm for partially connected 3D-NoCs. The routing algorithm is adaptive and tolerates the faults on vertical links as compared to the predesigned routing algorithms. Our results show a 40 À 50% improvement in the fraction of intact inter-level communications when the fault tolerant algorithm is used. This routing algorithm is lightweight and has only one virtual channel along the Y dimension.

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2D-NoCs have been the mainstream approach used to interconnect multi-core systems. 3D-NoCs have emerged to compensate for deficiencies of 2D-NoCs such as long latency and power overhead. A low-latency routing algorithm for 3D-NoC is designed to accommodate high-speed communication between cores. Both simulation and analytical models are applied to estimate the communication latency of NoCs. Generally, simulations are time-consuming and slow down the design process. Analytical models provide, within a fraction of the time, nearly accurate results which can be used by simulation to fine-tune the design. In this paper, a high performance and adaptive routing algorithm has been proposed for partially connected 3D-NoCs. Latency of the routing algorithm under different traffic patterns, different number of elevators and different elevator assignment mechanisms are reported. An analytical model, tailored to the adaptivity of the algorithm and under low traffic scenarios, has been developed and the results have been verified by simulation. According to the results, simulation and analytical results are consistent within a 10 percent margin.

The cost and reliability issues of TSVs move 3D-NoCs toward heterogonous designs with limited number of TSVs. However, designing a deadlock-free routing algorithm for such heterogonous architectures is extremely challenging due to the increased possibilities of forming cycles between and within layers for 3D designs. In this paper, we target designing a routing algorithm for heterogeneous 3D-NoCs with the capability of working under the technical limit in which there is just one TSV in the network. This algorithm is light-weight and provides adaptivity by using only one virtual channel along the Y dimension.

Abstract-3D-NoC has emerged to provide fast and power efficient connection between the layers of 2D-NoCs using Through-Silicon-Vias (TSV). Thermal stress, warpage, impurities and misalignment during the manufacturing process make these expensive TSVs vulnerable to faults. Chips with faulty TSVs should be either discarded or utilized by providing a proper fault-tolerant method. In this paper, we target designing a reconfigurable fault-tolerant routing algorithm capable of tolerating fabrication-time or run-time TSV failures. The proposed algorithm ensures a fault-free communication between any two nodes in the presence of TSV failures. Experimental results show that the proposed fault-tolerant routing algorithm provides 100% reliability as long as there is one healthy TSV in the eastmost or westmost column. The reliability of the counterpart algorithm, the Elevator-first routing algorithm, drops to 75% and 45% in presence of one and two faulty TSVs, respectively.

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