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From
•>>May 2006
Giuseppe Caire answers
a few questions about this month's fast moving front in the
field of Computer Science.
Field: Computer Science
On the achievable throughput of a multiantenna Gaussian broadcast channel
Authors: Caire,
G;Shamai, S
Journal: IEEE TRANS INFORM THEORY 32 2003, 49 (7): 1691-1706, JUL 2003
Addresses:
EURECOM, F-06904 Sophia Antipolis, France.
EURECOM, F-06904 Sophia Antipolis, France.
Technion Israel Inst Technol, Dept Elect Engn, IL-32000 Haifa, Israel.
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 Why
do you think your paper is highly cited?
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“...downloading large files and streaming
multimedia content has become the killer application for wireless systems.”
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Our paper posed a very relevant problem in wireless
communications. Namely, the capacity of a wireless downlink
channel when the base station has multiple antennas. This problem
belongs to a class of problems, called "non-degraded
broadcast channels" in information theory, for which there is
no known general capacity formula. Hence, it is difficult by its
very nature.
Furthermore, our paper provides the first (partial) solution to
the problem by providing the key elements that have been used by
following researchers to completely solve the problem in the two
years since our paper appeared.
Does
it describe a new discovery, methodology, or synthesis of knowledge?
It describes a new problem, and it provides both a partial
solution and the main tools for its complete solution.
Furthermore, these tools are not only mathematical artifacts
useful in proving theorems, but point to the very specific channel
coding and signal processing techniques that eventually will lead
to technological advances and practical implementations.
Could
you summarize the significance of your paper in layman’s terms?
The downlink—from base station to the mobiles—of a wireless
system has been recognized to be the system bottleneck of modern
data and multimedia-oriented wireless systems. This is because
downloading large files and streaming multimedia content has
become the killer application for wireless systems.
Our paper shows that it is indeed possible to increase the
downlink capacity by a factor equal to the number of antennas at
the base station. This paves the way for the implementation of
extremely efficient high data rate downlink systems, for better
services for wireless data and multimedia, which is the essence of
3G and the evolution thereof.
How
did you become involved in this research, and were there obstacles
along the way?
The impetus for research was inspired by practical problems and
also by a discussion with my coauthor, professor Shlomo
Shamai of the Technion - Israel
Institute of Technology in Haifa, Israel. The main obstacles were
of a theoretical nature and, since the problems were new,
we needed to develop new tools in order to solve them.
Giuseppe Caire (Professor)
EE Department, Viterbi School of Engineering
University of Southern California
Los Angeles, CA, USA
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