Shuffle-Exchange Mesh Topology for Networks-on-Chip

Abstract

Network-on-Chip (NoC) is a promising communication paradigm for multiprocessor system-on-chips. This communication paradigm has been inspired from the packet-based communication networks and aims at overcoming the performance and scalability problems of the shared buses in multi-core SoCs (System on Chips)(Benini & Mecheli, 2002). Although the concept of NoCs is inspired from the traditional interconnection networks, they have some special properties which are different from the traditional networks. Compared to traditional networks, power consumption is the first-order constraint in NoC design (Ogras et al., 2005). As a result, not only should the designer optimize the NoC for delay (for traditional networks), but also for power consumption. The choice of network topology is an important issue in designing a NoC. Different NoC topologies can dramatically affect the network characteristics, such as average inter-IP distance, total wire length, and communication flow distributions. These characteristics, in turn, determine the power consumption and average packet latency of NoC architectures. In general, the topologies proposed for NoCs can be classified into two major classes, namely regular tile-based and application-specific. Compared to regular tile-based topologies, application-specific topologies are customized to give a higher performance for a specific application. Moreover, if the sizes of the IP cores of a NoC vary significantly, regular tile-based topologies may impose a high area overhead. This area overhead can be compensated by some advantages of regular tile-based architectures. Regular NoC architectures provide standard structured interconnects which ensures well-controlled electrical parameters. Moreover, usual physical design problems like crosstalk, timing closure, and wire routing and architectural problems such as routing, switching strategies and network protocols can be designed and optimized for a regular NoC and be reused in several SoCs. The mesh topology is the simplest and most popular topology for today’s regular tile-based NoCs. On the other hand, the shuffle-exchange topology is a well-known network structure which was initially proposed by stone (Stone, 1971) as an efficient topology for multicomputer interconnection networks. Several researchers have studied the topological 5