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Alumnus Fellow Sets Standard
Next Generation Wireless to Use New Transmit Diversity Scheme
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of this article.
 When
the International Telecommunications Union (ITU)
met last year, one of the standards adopted for the third generation
(3G) standard for cellular wireless communications was in part
developed by a former Bradley Fellow, R. Michael Buehrer (Ph.D.,
'96).
A Distinguished Member of the Technical Staff at Bell
Labs - Lucent Technologies, Buehrer was on a two-person team
that developed a transmit diversity method for cellular communications.
"It was pretty exciting," Buehrer said. "Rob Soni
and I were able to develop a concept, sit down and analyze it,
simulate it to show that it works, take it to the product and
standards people, and prove that it is useful." Soni is
also a Member of the Technical Staff who works in the wireless
communications area.
"We spent the better part of a year pushing the idea through
the global standards body," Buehrer remarked. "The
introduction to the politics of global standards was quite an
education." Without significant assistance from the Lucent
standards team regarding politics and other aspects of the standards
effort, their standard would not have gone through, he added.
While transmit diversity is not a new idea, only recently have
researchers spent significant time analyzing it and proposing
it for wireless standards. "In a wireless system, there
is a good bit of signal fading - you can be on your cell phone
and hear your call go out," Buehrer explained. "When
transmit diversity is used, two signals are sent to your receiver
simultaneously, so that if one fades, the other will not."
The method Buehrer and Soni developed improved upon older methods
by more judiciously using the two antennas at the base station.
"The method that was being proposed originally was highly
dependent on the error correction coding scheme used. Our new
method was not," he said.
When implemented, Buehrer's concept will help maintain signal
quality, which is even more critical in the coming third generation
products than it has been in current devices. Broadband 3G devices
are expected to deliver voice, video, and data, via wireless
cellular networks, at rates up to 2 Mbits per second. Typical
cell phones today employ rates of about 8 kbits per second.
Efficiently transmitting large amounts of data wirelessly is
the next frontier in telecommunications, he said. "A couple
of researchers have developed concepts that are going to open
wide the possibilities," he said. "We'll have the technology.
People actually will be able to have their telephone search the
Internet and download recipes, or homework."
A Corporate Researcher
A member of one of the last big, corporate research laboratories,
Buehrer works with Bell Labs' Wireless Signal Processing Group,
in the Advanced Wireless Technology Lab in Whippany, New Jersey.
He finds his time divided between applied and fundamental research
in transmit diversity and intelligent antenna concepts and multiuser
detection.
"We tend to move back and forth between projects,"
he said. "Some of our research is limited to product specific
tasks with a limited range of choices. Other projects are more
open ended and open to the researcher's interest." He has
developed a synergy between his applied and basic research projects.
"I learn a lot on the applied projects and often use that
experience to develop my own ideas of questions to pursue independently,"
he said.
"What I love most about a job in research is that it all
comes down to problem solving," he commented. "You
have a problem and a toolbox of ideas and concepts. You attack
that problem with all you have and develop new tools. Basically,
you decide what's wrong, and you fix it."
He also enjoys being able to publish some of his work. "Many
things are proprietary and cannot be released, but I'm able to
publish enough to keep in touch with the academic research community
and researchers at other companies." At last year's Annual
Virginia Tech Symposium on Wireless Personal Communications,
he presented papers on three different areas of his research.
The challenge in wireless research, he said, is "trying
to get your arms around a whole problem. It is easy, when you
are dealing with a whole cellular network, to focus on a small
part. Trying to understand the rest of the picture, however,
is the biggest challenge."
Buehrer has recently joined the faculty of the New Jersey Institute
of Technology as an adjunct professor. This semester, he is teaching
a course in communications systems. "What I enjoy about
teaching is that it gets me back to the fundamentals, which helps
my research. On the other hand, my research experience definitely
helps with teaching my class," he said.
A Leap to The Big Leagues
Buehrer said that he never imagined himself as a Ph.D. researcher
at a first-rate research laboratory. "I might have hoped
it, but I would not have believed it." He earned his B.S.
and M.S. degrees in EE at the University of Toledo, where he
fell in love with communications. The best teacher he had as
an undergraduate taught communications. "When you have a
good teacher, it makes it that much more interesting," he
commented. "That class sparked my interest."
He wanted to jump to a bigger school for his Ph.D. degree,
with the hopes of then being able to jump to one of the bigger
companies. It was a communications textbook written by Charles
Bostian and Tim Pratt that first interested him in Virginia Tech.
"I felt as though I knew Bostian and Pratt and some of the
work at Tech through their textbook," he said. When he was
offered the Bradley Fellowship, he chose Virginia Tech over the
University of Michigan.
"I was leaning toward Michigan, but when I saw how beautiful
Blacksburg was, and I was awarded the Fellowship, I came to Tech
and was able to participate in the excellent communications research
there." Buehrer did his dissertation under Brian Woerner
on The Application of Multiuser Detection to Cellular CDMA.
"Being able to do good work at a well known school made
all the difference," he said. "The Bradley Fellowship
played a large part in where I am today."
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