Surface Wave Communication System for On-Chip and Off-Chip Interconnects Ammar Karkar, * Ra’ed Al-Dujaily and Alex Yakovlev School of Electrical and Electronic Engineering Newcastle University Newcastle upon Tyne, UK {a.j.m.karkar, raaed.aldujaili, alex.yakovlev}@ncl.ac.uk Kenneth Tong Department of Electrical and Electronic Engineering University College London London,UK K.tong@ucl.ac.uk Terrence Mak Department of Computer Science and Engineering The Chinese University of Hong Kong Hong Kong, China stmak@cse.cuhk.edu.hk ABSTRACT Network-on-chip (NoC) is a communication paradigm that has emerged to tackle different on-chip challenges and satisfy different demands in terms of high performance and econom- ical interconnect implementation. However, merely metal based interconnect pursuit offers limited scalability with the relentless technology scaling. To meet the scalability de- mand, this paper proposes a new hybrid interconnect fabric empowered by metal interconnect NoC and Zenneck surface Waves Interconnect (SWI) technology. Our initial results show a considerable power reduction (9 to 17%) and perfor- mance improvement (35%) of the proposed hybrid architec- ture compared to regular NoC. These results are achieved over relatively small hardware and area overhead (2.29% of die). This paper explores promising potentials of SWI for future System-on-Chip (SoC) global communication. Categories and Subject Descriptors B.4.3 [Interconnections]; B.7.1 [Design] Keywords NoC, Zenneck surface wave, Global communication 1. INTRODUCTION Complementary-metal-oxide-semiconductor (CMOS) tech- nology is scaling toward the ultra-large-scale integration (ULSI). This rapidly increases size and complexity of System on Chip * Ammar Karkar is also a staff member with the University of Kufa in Najaf-Iraq and sponsored by the HCED in Iraq to finish his Ph.D. email: ammar.karkar@uokufa.edu.iq. Permission to make digital or hard copies of all or part of this work for personal or classroom use is granted without fee provided that copies are not made or distributed for profit or commercial advantage and that copies bear this notice and the full citation on the first page. To copy otherwise, to republish, to post on servers or to redistribute to lists, requires prior specific permission and/or a fee. NoCArc ’12 , December 1, 2012, Vancouver, BC, Canada Copyright 2012 ACM 978-1-4503-1540-1/12/12 ...$15.00. (SoC). As result, a growing burden lies on interconnect fab- ric. Regular metal NoC struggles to match this scalability especially for global communication in terms of latency, and energy (J/b) [1, 2]. For local communication the length of the wire is scaling down with gate size, while wire length for global communication remains the same. Moreover, the cross section of the wire is decreasing [1]. this results in increasing the wire resistivity ,which causes higher power dissipation. Therefore, the issue is not only that metal wire does not scale enough to match future interconnect require- ments, but also projections show it might get worse in terms of power and performance. This is inspiring many studies to find alternative communication fabric such as radio fre- quency (RF) [3–6], optical interconnect [7–9], and 3D IC technology [10,11]. Unlike optical interconnect that requires integration of non-CMOS devices, RF is compatible with CMOS technology. Therefore, it has much lower implemen- tation overhead and cost than optical interconnect. The third fabric is 3D IC technology, which has more industrial challenges in terms of heat, thinning the wafer, inter-device layer alignment [1, 12]. Moreover, RF devices consume less power and area and offer competitive latency reduction than optical fabric and 3D IC. Thus, RF seems to be the best option for alternative NoC fabric. The RF technology lit- Figure 1: Zenneck surface wave propagation decay which is significantly better than free space propagation [13] erature has explored the implementation options of RF in terms of free space wireless [14] and waveguide transmission line RF [3, 4]. Wireless RF has a number of advantages. It naturally broadcasts signal to all the nodes in the cover- age area. Also, it eliminates the need for transmission media which drains the die area. On the other hand, RF waveguide transmission lines dissipate less power and longer transmit- ting distance. The new Zenneck surface wave combines the best features of these two types of RF. This technology is an NoCArc 2012 — December 1, 2012, Vancouver, Canada 11