1892 IEEE TRANSACTIONS ON COMPUTER-AIDED DESIGN OF INTEGRATED CIRCUITS AND SYSTEMS, VOL. 34, NO. 12, DECEMBER 2015 Low Energy yet Reliable Data Communication Scheme for Network-on-Chip Nima Jafarzadeh, Maurizio Palesi, Member, IEEE, Saeedeh Eskandari, Member, IEEE, Shaahin Hessabi, Member, IEEE, and Ali Afzali-Kusha, Senior Member, IEEE Abstract—In this paper, a low energy yet reliable communi- cation scheme for network-on-chip is suggested. To reduce the communication energy consumption, we invoke low-swing sig- nals for transmitting data, as well as data encoding techniques, for minimizing both self and coupling switching capacitance activity factors. To maintain the communication reliability of communication at low-voltage swing, an error control cod- ing (ECC) technique is exploited. The decision about end-to-end or hop-to-hop ECC schemes and the proper number of detectable errors are determined through high-level mathematical analysis on the energy and reliability characteristics of the techniques. Based on the analysis, the extended single error correction double-error detecting end-to-end coding technique with three bits of error detection is used in the network layer. For mini- mization of the self and coupling switching capacitance activity factors, the odd, even, full invert scheme is employed in the data link layer. This coding has an inherent error detection probability for the flits, which is exploited in the suggested tech- nique. The efficiency of the scheme is studied by using both synthetic and real traffic scenarios. The study reveals savings of up to 43% and 58%, for power dissipation and energy consumption, respectively, without any significant performance degradation and overhead in the network interface. Index Terms—Data encoding, end-to-end coding, energy analysis, hop-to-hop coding, interconnection on chip, low power, low-swing signaling, network-on-chip (NoC), reliable data coding. I. I NTRODUCTION T O MANAGE the increasing complexity of on- chip communications in system-on-chip (SoC), the network-on-chip (NoC) design paradigm has been Manuscript received July 2, 2014; revised November 29, 2014 and February 18, 2015; accepted April 3, 2015. Date of publication June 2, 2015; date of current version November 18, 2015. The work of N. Jafarzadeheh and S. Eskandari was supported by the Tehran South Branch, Islamic Azad uni- versity under Grant 08-14-5-913. This paper was recommended by Associate Editor V. Narayanan. (Corresponding author: Nima Jafarzadeh.) N. Jafarzadeh is with the Department of Computer Engineering, Islamic Azad University, South Tehran Branch, Tehran 1151863411, Iran (e-mail: n_jafarzadeh@azad.ac.ir). M. Palesi is with the Kore University of Enna, Enna 94100, Italy (e-mail: maurizio.palesi@unikore.it). S. Eskandari is with the Department of Computer Engineering, Islamic Azad University, Science and Research Branch, Tehran 14515-775, Iran (e-mail: s.eskandari@ieee.org). S. Hessabi is with the Department of Computer Engineering, Sharif University of Technology, Tehran 11365-9517, Iran (e-mail: hessabi@sharif.edu). A. Afzali-Kusha is with the School of Electrical and Computer Engineering, College of Engineering, University of Tehran, Tehran 14395, Iran (e-mail: afzali@ut.ac.ir). Color versions of one or more of the figures in this paper are available online at http://ieeexplore.ieee.org. Digital Object Identifier 10.1109/TCAD.2015.2440311 suggested [1]. In these systems, which may consist of many cores, minimizing power consumption is the critical challenge. A relevant fraction of the total power budget is due to the on-chip communication system. In NoCs, different components including links, crossbar switches, and buffers, take part in the communication, and dissipate their own power. For example, inspecting the power breakdowns in three mesh NoCs reveal 39%, 31%, and 17% for the links, 30%, 33%, and 15% for the crossbar switches, and 31%, 35%, and 22% for the buffers in RAW, TRIPS, and TeraFLOPS, respectively [2]–[4]. As these numbers show, the link power forms a major portion of the communication in NoCs. The metal wires, which form the links, are used for physical data transmission. Furthermore, as the technology scales the wires become more power hungry [5]. Therefore, it is critical to reduce the power consumption of the links. The power consumption of the links is proportional to the signal swing voltage, and both self and coupling capacitance switching activity factors. Reducing the swing and activity factors are well-known techniques to reduce the power consumption of the links in NoCs (see [6]–[10]). The former may be achieved by using a low-swing driver while the latter may be realized by using encoding techniques. Other techniques, such as increasing physical separations between wires or shielding techniques, may also be used to reduce the switching capacitance. One method to decrease the switching energy is to lower the supply voltage. This, however, may lead to performance degradation. To overcome this problem, the threshold voltage should be lowered as well. The reduction in the threshold volt- age increases the leakage current. Therefore, optimal values for the supply and threshold voltages should be determined. Low- swing signaling may be an effective approach to high-speed energy-efficient communication [11]. This, however, requires the design of receivers with good adaptation to line impedance and high sensitivity [12]. The communication reliability is a critical challenge in the design of low-swing signaling in NoCs, which has to be provided despite the decreased noise margins. Therefore, suitable coding techniques need to be exploited for detecting errors and increasing the reliability. A portion of reliability increase may be compromised with link power dissipation by reducing the link swing voltage. This reduction may be continued till one reaches the reliability of the uncoded data transfer with normal voltage swing. In addition, for error detection, a coding scheme may be used to reduce the overall switching activities of self and 0278-0070 c  2015 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.