The Research Of Topology In Network On Chip

As the integrity of SoC growing up, the original bus interconnection architecture cannot satisfy communication among IP blocks efficiently. In order to coyer theshortage of bus interconnection architecture, Network on Chip as a new solution was put forward.The research of NoC topology is one of the important area of NoC technology. NoC topology defined the layout and the way of interconnection between network nodes and links, which influenced the information transmission speed, the capacity of fault-tolerant, routing algorithm and other areas. Aiming at the NoC, a great deal of prototypes and research methods have been proposed recently. However, the problem of chip size and energy consumption as well as the method of physical layout and other issues have had no mature solution yet. For this reason, this paper studied topology of NoC, the main contributions in this paper are as below:Firstly, based on analyzing the topologys of Octagon, BFT, Mesh, Torus, a new topology named NST was proposed to solve the problems of single point failure in Octagon and the long diameter in Mesh. NST uses he hexagonal structure as the basic structure. Two adjacent hexagons shared the same side when NST extends. In this paper, the cabling design and the physical wiring diagram about NST were built, which reduced the number of links so that the area of chip was also decreased effectively. At the same time, the routing algorithm on NST was designed and implemented. The algorithm selected the data output port according to the relative position between the source node and the target node, which avoided deadlock and live-lock phenomenon effectively. By analyzing the experimental data using OPNET, the results showed that NST have advantages in the aspects of network delay, throughput, energy consumption and chip area than the used topology such as Mesh, Torus, BFT, Octagon and so on.Secondly, according to the good local characteristics of cluster-based topology, a new topology called CMesh was put forward. In Cmesh, all nodes were ordered as in accordance with the rules of the inerratic two-dimensional net, an intermediate level was joined between the network and nodes, which named cluster-subnet. Each subset was connected to each other through router, which arrange as Mesh. In the internal of subnet, a center router was connected with other four routers in this subnet. So a cluster-interconnect structure was formed. In this paper, CMesh and Mesh structure was simulated and compared. The results showed that CMesh structure had less delay and higher throughput than Mesh structure under hotspot flow and normalized flow.