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Abstract
The objective
of this tutorial is to illustrate
that the principle of superposition
of power is not valid in electrical
engineering, and hence not applicable
to analysis of multi antenna systems.
In electrical engineering, it is
the voltage and the current that
can be superposed and that is why
another name of it is field theory,
as the voltages and the currents
are the results of the fields. Examples
will be presented to illustrate
how the Maxwellian physics can be
introduced to improve the performance
of multi antenna systems. This group
also includes MIMO systems. Consider
two plane waves of respective power
densities 100 and 1 W/m2
that are allowed to interact with
each other. Even though one of the
waves is only 1% in power density
of the other, if the two waves interfere
constructively or destructively,
the resulting variation in the power
density received is not 101 or 99
W/m2 but rather
  or
 resulting
in 121 or 81 W/m2 – a
40% change and not 1%, since it
is the field or voltages or currents
that can be added in the electrical
engineering context, and not the
powers. Hence, the first objective
of this presentation is to define
the appropriate metric for comparison
of performance between various multiantenna
systems.
Also, we examine
the phenomenon of height-gain
in wireless cellular communication,
and illustrate that under the current
operating scenarios where the base
station antennas are deployed over
a tall tower, the field strength
actually decreases with the height
of the antenna over a realistic
ground and there is no height gain
in the near field. Therefore, to
obtain a scientifically meaningful
operational environment the vertically
polarized base station antennas
should be deployed closer to the
ground. Also, when deploying antennas
over tall towers it may be more
advantageous to use horizontally
polarized antennas than vertically
polarized for communication in cellular
environments. Examples will be presented
to illustrate these cases. In addition
we discuss what is the criterion
for the far field of an antenna
over an imperfect ground plane.
This is quite significant as an
antenna has no defined radiation
pattern in the near field!
In addition,
when comparing the performance between
systems, the input power needs to
be the same for all the systems.
It becomes clear that the use of
the Hartley definition of channel
capacity is more appropriate to
use for a multiantenna system rather
than the Shannon Channel capacity
which uses the superposition of
power as Shannon did not develop
the theory for wireless systems
where interference is present and
the limiting factor is not background
thermal noise. From a physics perspective,
it is illustrated that a 1×1 SISO
system may perform better than a
2×2 MIMO system. However, as the
concept of channel capacity is developed
on purely mathematical grounds based
on entropy, it is difficult to relate
the physics to the mathematics as
the capacity is defined with respect
to background thermal noise whereas
no receiver can accept a signal
weaker than 100 µV/m in the absence
of interference, which is far above
the background noise. One of the
goals is also to illustrate that
an N×N MIMO system
does not necessarily have better
performance than N separate
SISO systems, using the same total
input power.
Finally, an embarrassingly
simple solution is presented based
on reciprocity that can decouple
all the receive channels leading
to uncoupled MISO systems which
can operate in any environment and
under all scenarios. In this situation,
it is not even necessary to characterize
the electromagnetic environment
through a singular value decomposition.
Examples will be presented to illustrate
this scenario and compare its performance
with conventional systems illustrating
that this system can perform equally
well and sometimes better than a
MIMO system.
About the speakers
Tapan K. Sarkar
received
the B.Tech. degree from the Indian
Institute of Technology, Kharagpur,
in 1969, the M.Sc.E. degree from
the University of New Brunswick,
Fredericton, NB, Canada, in 1971,
and the M.S. and Ph.D. degrees from
Syracuse University, Syracuse, NY,
in 1975.
From 1975 to
1976, he was with the TACO Division
of the General Instruments Corporation.
He was with the Rochester Institute
of Technology, Rochester, NY, from
1976 to 1985. He was a Research
Fellow at the Gordon McKay Laboratory,
Harvard University, Cambridge, MA,
from 1977 to 1978. He is now a Professor
in the Department of Electrical
and Computer Engineering, Syracuse
University. His current research
interests deal with numerical solutions
of operator equations arising in
electromagnetics and signal processing
with application to system design.
He obtained one of the “best solution”
awards in May 1977 at the Rome Air
Development Center (RADC) Spectral
Estimation Workshop. He received
the Best Paper Award of the IEEE
Transactions on Electromagnetic
Compatibility in 1979 and in the
1997 National Radar Conference.
He has authored or coauthored more
than 300 journal articles and numerous
conference papers and 32 chapters
in books and fifteen books, including
his most recent ones, Iterative
and Self Adaptive Finite-Elements
in Electromagnetic Modeling
(Boston, MA: Artech House, 1998),
Wavelet Applications in Electromagnetics
and Signal Processing (Boston,
MA: Artech House, 2002), Smart
Antennas (IEEE Press and John
Wiley & Sons, 2003), History
of Wireless (IEEE Press and
John Wiley & Sons, 2005), and
Physics of Multiantenna Systems
and Broadband Adaptive Processing
(John Wiley & Sons, 2007), Parallel
Solution of Integral Equation-Based
EM Problems in the Frequency Domain
(IEEE Press and John Wiley
& Sons, 2009), and Time and Frequency
Domain Solutions of EM Problems
using Integral Equations and a Hybrid
Methodology (IEEE Press and
John Wiley & Sons, 2010) .
Dr. Sarkar is
a Registered Professional Engineer
in the State of New York. He received
the College of Engineering Research
Award in 1996 and the Chancellor’s
Citation for Excellence in Research
in 1998 at Syracuse University.
He was an Associate Editor for feature
articles of the IEEE Antennas and
Propagation Society Newsletter (1986-1988),
Associate Editor for the IEEE Transactions
on Electromagnetic Compatibility
(1986-1989), Chairman of the Inter-commission
Working Group of International URSI
on Time Domain Metrology (1990–1996),
distinguished lecturer for the Antennas
and Propagation Society from (2000-2003),
Member of Antennas and Propagation
Society ADCOM (2004-2007), on the
board of directors of ACES (2000-2006),
vice president of the Applied Computational
Electromagnetics Society (ACES),
and a member of the IEEE Electromagnetics
Award board (2004-2007). He is currently
an associate editor for the IEEE
Transactions on Antennas and Propagation.
He is also on the editorial board
of Digital Signal Processing – A
Review Journal, Journal of Electromagnetic
Waves and Applications and Microwave
and Optical Technology Letters.
He is the chair of the International
Conference Technical Committee of
IEEE Microwave Theory and Techniques
Society # 1 on Field Theory and
Guided Waves. He is a member of
Sigma Xi and International Union
of Radio Science Commissions A and
B.
He is also the
president of OHRN Enterprises, Inc.,
a small business incorporated in
New York state (1985) performing
various research work for various
organizations in system analysis.
He received Docteur
Honoris Causa both from Universite
Blaise Pascal, Clermont Ferrand,
France in 1998 and from Politechnic
University of Madrid, Madrid, Spain
in 2004. He received the medal of
the friend of the city of Clermont
Ferrand, France, in 2000.
Magdalena
Salazar-Palma
was born in Granada,
Spain. She received the MS and PhD
degrees in Ingeniero de Telecomunicación
(Electrical and Electronic Engineer)
from Universidad Politécnica
de Madrid (UPM), Spain. She
has been Profesor Colaborador
and Profesor Titular de Universidad
at the Department of Signals,
Systems and Radiocommunications,
UPM. Since 2004 she has been
with the Department of Signal Theory
and Communications, College of Engineering,
Universidad Carlos III de Madrid,
Spain, where she is Catedrático
(Full Professor) and Chairperson
of the Department. She has developed
her research in the areas of electromagnetic
field theory; computational and
numerical methods for microwave
passive components and antenna analysis;
network and filter theory and design;
design, simulation, optimization,
implementation, and measurement
of microwave circuits both in waveguide
and integrated (hybrid and monolithic)
technologies; and history of telecommunications.
She has authored
6 books and 23 contributions (chapters
or articles) for books published
by international editorial companies,
13 contributions for academic books
and notes, 61 papers in scientific
journals, 225 papers in international
conferences, symposiums, and workshops,
69 papers in national conferences
and more than 80 project reports,
short course notes, and so on. She
has coauthored two European patents
and one US patent, and several software
packages for the analysis and design
of microwave and millimeter wave
passive components, antennas and
antenna arrays, as well as computer
aided design (CAD) of advanced filters
and multiplexers for space applications.
She has delivered numerous invited
presentations, lectures, and seminars.
She has lectured in a number of
short courses, some of them in the
frame of Programs of the European
Community and others in conjunction
with IEEE International AP-S Symposium
and IEEE MTT-S Symposium. She has
participated at different levels
(researcher or principal investigator)
in a total of 80 research projects
and contracts, financed by international,
European, and national institutions
and companies, among them: the National
Science Foundation, USA; the European
Office of Aerospace Research and
Development of the Air Force Office
of Scientific Research (one of the
Air Force Research Laboratory Directorates),
USA; the European Union; Spain Inter-ministry
Commission of Science and Technology
(CICYT), Spain Ministry of Education
and Culture (MEC), and Council of
Education of the Regional Government
of Madrid (CAM). She has assisted
the Spain National Agency of Evaluation
and Prospective (ANEP) and the Spain
Inter-ministry Commission of Science
and Technology (CICYT) in the evaluation
of projects, research grants applications,
and so on. She is member of the
Accreditation Committee of Full
Professors of the Spanish Agency
of Quality Evaluation and Accreditation
(ANECA). She has also served in
several evaluation panels of the
Commission of the European Communities.
She has been a member of the editorial
board of three scientific journals.
She has been associated editor of
several scientific journals, among
them, IEEE Antennas and Wireless
Propagation Letters. She is associated
editor of the European Microwave
Association Proceedings and the
International Journal of Antennas
and Propagation. She is member of
the Technical Program Committees
of several international and national
symposiums and reviewer for different
international scientific journals,
symposiums, and editorial companies.
She is a registered engineer in
Spain. She has received two individual
research awards.
Since 1989, she
has served IEEE under different
volunteer positions: vice chairperson
and chairperson of IEEE Spain Section
AP-S/MTT-S Joint Chapter, chairperson
of IEEE Spain Section, Membership
Development Officer of IEEE Spain
Section, member of IEEE Region 8
Committee, member of IEEE Region
8 Nominations and Appointments Subcommittee,
chairperson of IEEE Region 8 Conference
Coordination Subcommittee, member
of IEEE WIE Committee, liaison between
IEEE WIE Committee and IEEE Regional
Activities Board, chairperson of
IEEE Women in Engineering (WIE)
Committee, member of IEEE Ethics
and Member Conduct Committee, member
of IEEE History Committee, member
of IEEE MGAB (Member and Geographic
Activities Board) Geographic Unit
Operations Support Committee, and
member of IEEE AP-S Administrative
Committee. Presently she is serving
as member of IEEE Spain Section
Executive Committee (officer for
Professional Development), member
of IEEE MTT-S Subcommittee # 15,
member of IEEE AP-S Transnational
Committee. In December 2009 she
was elected 2011 President of IEEE
AP-S Society, acting as President
Elect during 2010 and Past President
from 2012 onwards.
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