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Opportunistic Communications and Distributed Beamforming in Wireless Networks
***CANCELLED***
Dr. Patrick Mitran
Thursday, March 29, 2007
2:00PM ~ 3:30PM Harris Engineering Center 125
Abstract
It is well known in communications theory that spatial diversity can
greatly increase reliability over quasi-static wireless networks. In
practice, however, space or cost constraints often limit the number of
physical antennae--and hence "virtual" arrays provide the only method by
which traditional multi-antenna gains may be achieved. Here we describe
two such schemes which rely on collaboration amongst nodes, both with and
without channel state information. We first propose a purely opportunistic
communications protocol and prove that cooperative error control codes
exist for which the intra-cluster negotiation penalty is small and almost
all the diversity gain of a traditional space-time codes may be realized.
We then propose a collaborative beamforming protocol in which each node is
assumed to have a single isotropic antenna, and nodes work together to
realize coherent superposition in the far field. We analyze the
performance of ad hoc phased arrays in this context, and derive
statistical properties of the resultant beampatterns as well as their
performance in terms of directivity and beamwidth as a function of
(random) array size and spatial distribution.
Short Bio
Patrick Mitran received the Bachelor's and Master's degrees in
electrical engineering, in 2001 and 2002, respectively, from McGill
University, Montreal, PQ, Canada, and the Ph.D. degree from the Division
of Engineering and Applied Sciences, Harvard University, Cambridge, MA in
2006. In 2005, he interned as a research scientist for Intel Corporation
in the Radio Communications Lab. Currently he is a lecturer in the
Division of Engineering and Applied Sciences, Harvard University.
Currently he is interested in the study of cooperation and cognition in
wireless networks both from an information theorectical viewpoint as well
as coding theory and signal processing perspectives. This includes such
aspects as capacity analysis, distributed source/channel coding and
network coding. He is also interested in channels with timing errors such
as seen in magnetic recording channels.
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