Reconfigurable Intelligent Surfaces

[Tim Cash]

What is RIS?
Intelligent control of Meta-material surfaces to modify key performance
parameters to improve power beaming.

When is it available?
Today

Why do we care?

The loss mechanisms in wireless power transmission include:
free space path loss
reflection losses
diffraction losses
scattering losses
meta-material surface efficiencies

Making use of reconfigurable intelligent surfaces (RIS) will allow
efficient power beaming through intelligent control of physical properties:

Modulate Transmit Power to match receiver site(s) requirements
Modulate Efficiency of Transmit and Receive Operations within defined,
achievable limits
Match the dispatch-able energy of a single site to multiple diverse
rectennae across space
Allow for several simultaneous beams across multiple transmit and
receive sites
Match the Power Purchase Agreement (PPA) to physical conditions of
diverse locations at all times of day or night
Optimize the O&M operations across the life cycle for a power beaming
system using >100% online operational components so that maintenance can
be performed without affecting the load side demand

Emerging paradigm towards next generation of wireless power transmission:
− Breaking free from the postulate that regards the wireless power
environment as “fixed and uncontrollable”
− Introduce means to allow "programming" the wireless power environment
− Simple model of wireless power beaming environment: An assembly of
fixed power transmitters and receivers without flexibility in their
operational environment is old thinking
− Reconfigurable Intelligent Surfaces (RIS) allow a flexible design and
operational environment
− RIS Enabling technology: Metamaterial

Smart Power Beaming Environment (SPBE), SW Defined Environment (SDE)

RIS or intelligent reflecting surface (IRS) tune wireless power
transmission environments to allow energy efficiencies of transmitters
and rectennae to be modulated in real time through use of:

− Reconfigurable reflect arrays
− Liquid crystal meta-surfaces
− Programmable meta-materials

RIS will allow us to design the power beaming parameters, ie power
beaming efficiencies
We will be able to program the wireless power parameters in advance or
on the fly
RIS enabling technology is metamaterials
RIS is a 2D surface which can be placed somewhere in the environment
Change of RIS surface parameters done on the fly
Change of RIS power beaming angles done on the fly

There are different types of meta-materials and various frequency ranges
that they support
Silicon based varactor and pin diode based, or liquid crystal based
meta-materials
Control of impedance and reflection of EM Waves using Meta-materials
Varactor control impedance via voltage of impinging EM wave
Control of absorption of EM wave via meta-material
There are transparent meta-materials as well
Frequency range, power consumption of RIS are important KPI parameters

REFERENCES
Proceedings of the IEEE
Special Issue: Reconfigurable Intelligent Surfaces
Volume 110, Issue 9
September 2022
https://proceedingsoftheieee.ieee.org/september-2022/

SPECIAL ISSUE ON RECONFIGURABLE
INTELLIGENT SURFACES
Edited by M. Di Renzo and S. Tretyakov
https://spcc.committees.comsoc.org/special-interest-groups/sig-reflections/

Emerging Technology Initiative on Reconfigurable Intelligent Surfaces
(ETI-RIS): https://riseti.committees.comsoc.org/

Best Readings in RISs:
https://www.comsoc.org/publications/best-readings/reconfigurable-intelligent-surfaces

IEEE Proceedings Special Issue on RIS:
https://ieeexplore.ieee.org/xpl/mostRecentIssue.jsp?punumber=5

man-made structures become more and more electronically active, with
integrated electronics and wireless communication making the entire
environment intelligent
IEEE TRANSACTIONS ON SIGNAL PROCESSING, VOL. 66, NO. 10, MAY 15, 2018