security, device position discovery, and
user mobility prediction mechanisms
in the SDN world.
Recently, a related project—
VISORSURFa—was funded under the prestigious Future Emerging Technologies
call of the European Union Horizon
2020 framework. VISORSURF underwent a highly selective review phase,
with a 3% acceptance rate, and attracted
a total budget of 5. 7 million euros. The
multidisciplinary team of researchers is
developing the hardware and software
for the HyperSurfaces, expects to have
the first prototype within a year, and begin mass production soon afterward.
a A hypervisor for metasurface functions;
1. Akyildiz, I.F., Nie, S., Lin, S.-C., and Chandrasekaran, M.
5G roadmap: 10 key enabling technologies. Computer
Networks 106 (2016), 17–48.
2. Chen, H.-T., Taylor, A. J., and Yu, N. A review of
metasurfaces: Physics and applications. Reports on
Progress in Physics 79, 7 (2016), Physical Society,
3. Haupt, R. L. and Werner, D. H. Genetic Algorithms in
Electro-Magnetics. Wiley, N Y, 2007.
4. Li, L. et al. Electromagnetic reprogrammable coding-metasurface holograms. Nature Communications 8,
1 (2017), 197.
5. Li, Y. et al. Transmission-type 2-bit programmable
metasurface for single-sensor and single-frequency
microwave imaging. Scientific Reports 6 (2016).
6. Liaskos, C. et al. Design and development of software-defined metamaterials for nanonetworks. IEEE
Circuits and Systems Magazine 15, 4 (2015), 12–25.
7. Lim, D., Lee, D., and Lim, S. Angle- and polarization-insensitive metamaterial absorber using via array.
Scientific Reports 6 (2016).
8. Moghaddam, S.S. and Moghaddam, M. S. A
comprehensive survey on antenna array signal
processing. Trends in Applied Sciences Research 6, 6
(June 2011), 507–536.
9. Parashkov, R. et al. Large area electronics using
printing methods. In Proceedings of the IEEE 93, 7
10. Tassin, P., Koschny, T., and Soukoulis, C.M. Graphene
for terahertz applications. Science 341, 6146 (2013),
Christos Liaskos ( email@example.com) is a researcher
at the Foundation of Research and Technology (Hellas),
Ageliki Tsioliaridou ( firstname.lastname@example.org) is a researcher
at the Foundation of Research and Technology (Hellas),
Andreas Pitsillides ( Andreas.Pitsillides@ucy.ac.cy) is
a professor in the Department of Computer Science and
the head of the Networks Research Laboratory at the
University of Cyprus.
Sotiris Ioannidis ( email@example.com) is a member of
the staff at the Foundation of Research and Technology
Ian Akyildiz ( firstname.lastname@example.org) is the Ken Byers
Distinguished Chair Professor in the School of Electrical
and Computer Engineering at the Georgia Institute of
Technology in Atlanta, GA, USA, and member of the staff
at the University of Cyrus.
This work was funded by the EU H2020 FE TOPEN-RIA
project VISORSURF: A Hardware Platform for Software-driven Functional Metasurfaces (GA 736876).
Copyright held by authors.
tile acts as the object’s “
representative,” connecting to the external world.
Figure 4 illustrates the integration
of the programmable wireless environment to common network infrastructure
using the software-defined networking
(SDN) paradigm. 1 SDN has gained significant momentum due to the clear separation it enforces between the network control logic and the underlying hardware.
An SDN controller abstracts the hardware specifics (“southbound” direction)
and presents a uniform programming
interface (“northbound”) that allows the
modeling of network functions as applications. In this paradigm, HyperSurface
tiles are treated as wave “routers,” while
the commands to serve a set of users, for
example, as in Figure 2, are produced by
a wireless environment control application. The application takes as input the
user requirements and the global policies and calculates the fitting air paths. A
control loop is established with existing
device position discovery and access control applications, constantly adapting to
The scalability of the novel program-
mable wireless environments is a prior-
ity, both in software and hardware. In
terms of software, the additional over-
head comes from the optimization ser-
vice, as shown in Figure 4. As described,
however, the optimization pertains
to finding objective-compliant paths
within the graph of tiles, which is a well-
studied and tractable problem in clas-
sic networking. In terms of hardware,
the IoT gateway approach promotes
miniaturization, low manufacturing
cost, and minimal energy consump-
tion of electronics, favoring massive tile
deployments to cover an environment.
Moreover, the choice of metasurfaces
as the means for exerting electromag-
netic control has distinct scalability and
functionality benefits over alternatives.
Metasurfaces comprise thin metallic el-
ements and simple two-state switches,
facilitating their manufacturing using
large-area electronics methods (LAE)
for ultra-low production cost. 9 LAE can
be manufactured using conductive
ink-based printing methods on flexible
and transparent polymer films, incor-
porating simple digital switches such
as polymer diodes. 9 On the other hand,
alternatives such as antenna arrays8 re-
quire transceivers with accurate state
control and real-time signal-processing
capabilities, posing scalability consid-
erations in terms of size, power, and
Despite their simpler design, metasurfaces constitute the state of the art
in range of wave interaction types, and
with unique granularity. Advanced
frequency filtering, polarization control, and arbitrary radiation-pattern-shaping functions can be potentially
used for remodulating or “repairing”
waves in the course of their propagation. Even in simple wave routing and
absorbing functions, metasurfaces
provide a degree of direction control
so granular that it has been used for the
formation of holograms. 4 A high degree
of control granularity is required for 5G
ultra-high frequency communications,
as discussed earlier in this Viewpoint.
Moreover, novel dynamic metasurface
designs employ graphene, offering operation at the range of terahertz. 10
The design and implementation of
HyperSurfaces is a highly interdisciplinary task involving physics, material sciences, electrical engineering,
and informatics. The combined expertise of all these disciplines results
in significant value: programmable
wireless environments can be enabled for the first time, allowing for
programmatic customization of the
laws of electromagnetic propagation,
to the benefit of wireless devices. Programmable environments provide
a novel perspective for wireless communications, where the usual rigid
channel models are replaced by a
customizable software process. Apart
from unprecedented capabilities in
wireless systems, this new perspective can pave the way for a completely
new class of software applications,
with rich interactions with existing
a novel perspective