An Adaptive Output Selection Function Based on a Fuzzy Rule Base System for Network on Chip

In Network-on-chip design two of the most important performance indices are the average delay of packets and power dissipation. The first depends on the level of congestion of the communication system, the second is strongly influenced by the power dissipated by the links of a network-on-chip (NoC) which accounts for a significant fraction of the overall power dissipated by the on-chip communication fabric. Such fraction becomes more and more relevant as technology shrinks. The selection policy of the output port in the NOC router with adaptive routing function affects both the performance and power dissipation. In fact, generally a NOC with a lower average delay has a lower power dissipation on the links for transmission. The selection policies proposed in the literature have the object or the minimization of the average delay or in some cases the reduction of power dissipation. In this paper we propose a selection policy aimed at minimizing both the average delay and power consumption of the communication system of NoC based architectures. The proposed policy uses a cost function obtained using a Fuzzy Rule Base System (FRBS) with two inputs an one output. Inputs are the level of use of the buffers of the downstream routers, and the link power dissipation of the selected output. The output of FRBS is the cost function. The experimental results, obtained using a cycle accurate NoC simulator for different traffic scenarios, shows that the proposed selection policy outperforms other selection approaches both in terms of average delay and in terms on power dissipation and energy consumption.