Tuesday, September 22, 2015

Dynamic Power Reduction in NOC by Encoding Techniques #IJIRST Journal


Abstract:- As technology improve the size will be reduced, and the power dissipated by the links of a network-on-chip (NoC) is starts to participate with the power dissipate by the other element of communication system, for example the routers and the network interfaces (NIs). We design an set of data encoding technique by different schemes to decrease the power dissipation by an links of NoC, which optimizing the on-chip communication system not only in terms of performance but also in terms of power. The idea presented in this paper is base on encoding the packets before they are inserted in to the network in such a way as to minimize both the switching action and the coupling-switching action in the NoC’s link which represent the main factor of power dissipation. These schemes were universal and transparent with respect to the construct NoC fabric that means this application will not require any change in the router and link of architecture. These will be carried in both artificial and real traffic scenario. These effective of the proposed scheme will tolerate to save the energy consumption and power dissipation without changing the performance degradation and with less area consumption in the NI.  

Keywords: switching action, encoding, network-on-chip (NoC), low power, router, Network interfaces (NIs)

I.       Introduction

Moving towards silicon technology node to the next results faster and more efficient gates but slower because there is a more power hungry wires. More than 50% of total dynamic power is dissipate in interconnection in current processor, and this was expected to increase more over in the next several years. Global interconnect length does not scale with smaller transistors and local wires. Chip size remains relatively constant because the chip function continues for instance the RC delay increases exponentially. The RC delay in a 1-mm worldwide wire at the smallest pitch is superior to the intrinsic delay of a two-input NAND fan-out. If the raw computation horsepower seems to be un-limited, thanks to the ability of instance more core’s in a single silicon chip, scalable issue occur, due to making an efficient and reliable communication among the increasing number of core’s, become the real problem. The NOC invent is documented as the most feasible way to tackle with scalable and variability issue that characterize the ultra-deep sub-micron-meter.
Now a days in the on-chip communication issue is relevant, in some of the case more relevant than commutating related issue. The communication sub-system more and more impacts the usual designed objective, and also includes cost (i.e., area of silicon), performances, dissipation of power, consumption of energy and reliability. As technology improves the size is reducing and more fraction of total power is budget of the complex in more core of the system-on-chip (SoC) this is because of communication sub-system.
Here we attentation on the technique aim to minimize power dissipation by a network link. The power dissipation in the network is relevant as that dissipation by NIs, routers and it is giving that ordinary to increase the technology scale. We are representing the set of encoding schemes for data which is in binary formate, and it is operated at flit level, and an end-to-end basis, this allows us to minimize the switching action and coupling switching action at the link of an direction is traverse by a packet. This encoding schemes, were transparent by respect to router execution, and they are presented, discussed in both algorithmic-level and architectural level, it is assessed via the simulation in the artificial, real traffic scenario. These analysis gives an different aspects, metrics design, it include area of silicon, energy consumption and dissipation of power. From the results we can conclude that with these proposed encoding schemes that power will save and also energy will be save without changing any major degradation in the performance in the NIs.

II.       Motivation and Related work

The accessibility of chips is growing every year. In next few years, the accessibility of cores with 1000 cores is foreseen. Since the focus of this paper is to decrease the power dissipation by link which decreases the dynamic power, here we are going review the works in the area and link power reduction. Also these will include some technique. They are, use of shielding to  increase line-to-line space and repeater insertion. So above technique have large area consumption. One method is the data encoding technique, its mainly focus is to reduce the link power. The encoding technique’s is categorize in to two group. In 1st group we are going to decrease the power by the self-switching action of the each bus line and avoid the dissipation of power by coupling switching action.
These work concentrate on the different component of the inter connection network such as NIs, router, and link. Because these will reduce power dissipation by an link, in this paper, we are going to brief the review some works in the region of link power reduction. These include the technique that make use of shielding, which increase line-to-line space and repeater inserted. They all increases the silicon chip area. These encode scheme is an additional technique that is employed to reduce dissipation of power in link. The data encoding technique has been classified in to two class. In the first class, encoding technique concentrate on reducing the power due to self-switching action of separate bus line while ignoring an power dissipation due to their coupling-switching action. In these class, bus invert (BI) and INC-XOR have been proposed for these case that casual random data pattern is transmitte through the lines. On the other hand, gray code, T0, working-zone encoding, and T0-XOR were suggest for the case of correlation data pattern. Application particular approach have also been proposed

This class of encoding will not be appropriate to be applied in the deep sub-micron meter technological node where the coupling capacitance constitute an most important part of the total inter-connect capacitance. This will cause the power consumption due to the coupling-switching action to become a big fraction of the total power consumption in the links, that making the aforementioned techniques, which ignore such contributions, inefficient. The works in the second class concentrate on reducing power dissipation through the reducing the coupling-switching action. Among these schemes, the switching action is reduced by using many additional control lines. For example, the data bus width grows from 32 to 55. The techniques proposed in have a smaller number of control lines but the complexity of their decoding logic is high. The technique described as follows: first, the data are both odd inverted and even inverted, and afterwards transmission is perform using these kind of inversion which reduce more switching action. The coupling switching action it is reduced, this is compared with another, so we use a simple decoder although achieving a higher activity reduction.
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