Feature 58 IEEE CIRCUITS AND SYSTEMS MAGAZINE 1531-636X/16©2016IEEE FIRST QUARTER 2016 Digital Object Identifier 10.1109/MCAS.2015.2510199 Date of publication: 12 February 2016 A Survey of Emerging Interconnects for On-Chip Efficient Multicast and Broadcast in Many- Cores Ammar Karkar, Terrence Mak, Kin-Fai Tong, and Alex Yakovlev Abstract Networks-on-chip (NoC) have emerged to tackle different on-chip communication challenges and can satisfy different demands in terms of performance, cost and reliability. Currently, interconnects based on metal are reaching performance limits given relentless technology scaling. In particular, a performance bottleneck has emerged due to the demands for communica- tion in terms of bandwidth for multicasting and broadcasting. As a result, various state-of-the-art architectures have been proposed as alternatives and emerging interconnects including the use of optics or radio frequency (RF). This article presents a comprehensive survey of these various interconnect fabrics, and discusses their current and future potentials and obstacles as well. This article aims to drive the research community to achieve a better utilization of the merits of on-chip interconnects and addresses the challenges involved. New interconnect tech- nologies, such as optical interconnect, wireless NoC (WiNoC), RF transmission lines (RF-I) and surface wave interconnects (SWI), are discussed, evaluated and compared. Consequently, these emerging interconnects can continue to provide the cost efficiency and performance that are highly demanded for future many-core processors and high performance computing. IMAGE LICENSED BY ©DIGITAL VISION Ammar Karkar is with the School of Electrical and Electronic Engineering, Newcastle University, UK (e-mail: a.j.m.karkar@newcastle.ac.uk), and the IT Research Centre, University of Kufa, Iraq (e-mail: ammar.karkar@ uokufa.edu.iq). Terrence Mak is with Electronics and Computer Science, University of Southampton, UK (e-mail: tmak@ecs.soton.ac.uk). Kin-Fai Tong is with the Department of Electrical and Electronic Engineering, University College London, UK (e-mail: k.tong@ucl.ac.uk). Alex Yakovlev is with the School of Electrical and Electronic Engineering, Newcastle University, UK (e-mail: alex.yakovlev@newcastle.ac.uk).