Special Interest Group (SIG):
Reconfigurable Intelligent Surfaces for Smart Radio Environments (RISE)

About the SIG

Future wireless networks will be as pervasive as the air we breathe, not only connecting us but embracing us through a web of systems that support personal and societal well being. That is, the ubiquity, speed and low latency of such networks will allow currently disparate devices and services to become a distributed intelligent communications, sensing, and computing platform. Small cells, massive MIMO, millimeter-wave communications are three fundamental technologies that will spearhead the emergence of 5G wireless networks – Their advantages are undeniable. The question is, however, whether these technologies will be sufficient to meet the requirements of future wireless networks that integrate communications, sensing, and computing in a single platform. Wireless networks, in addition, are rapidly evolving towards a software-defined design paradigm, where every part of the network can be configured and controlled via software. In this optimization process, however, the wireless environment itself – the medium or channel – is generally assumed uncontrollable and often an impediment to be reckoned with. For example, signal attenuation limits the network connectivity, multi-path propagation results in fading phenomena, reflections and refractions from objects are a source of uncontrollable interference.

Recently, a new concept called Reconfigurable Intelligent Surfaces (RISs) has emerged wherein every environmental object is coated with man-made intelligent surfaces of configurable electromagnetic materials. These materials contain integrated electronic circuits and software that enable the control of the wireless medium. RISs can be realized in different ways, which include: (i) large arrays of inexpensive antennas that are usually spaced half of the wavelength apart; and (ii) metamaterial-based planar or conformal large surfaces whose scattering elements have sizes and inter-distances much smaller than the wavelength. Compared with other transmission technologies, e.g., phased arrays, multi-antenna transmitters, and relays, RISs require the largest number of scattering elements, but each of them needs to be backed by the fewest and least costly components. Also, no power amplifiers are usually needed.

For these reasons, RISs constitute a promising software-defined architecture that can be realized at reduced cost, size, weight, and power (C-SWaP design), which could potentially enable telecommunication operators to sculpt the communication medium that comprises the network. As such, RISs have the potential to change how wireless networks are designed, usher in that hoped-for wireless future, and are regarded as an enabling technology for realizing the emerging concept of smart radio environments (SREs). But, RISs are not currently well-understood.