Downlink Beamforming for Mobile Communications
Mr. Alberto Arredondo
Electrical and Computer Engineering
The University of Texas at Austin
Austin, TX
Wednesday, November 28th, 9:00 AM, ENS 637
alberto@ece.utexas.edu
Abstract
This dissertation introduces modeling and prediction of the
downlink spatial signature. The primary application of this technique is
to time-division duplex communications systems. In such systems, downlink
beamforming based on spatial signatures suffers when the mobile user is
truly mobile. In these cases, the uplink spatial signature no longer
resembles the downlink spatial signature. I will show that the spatial
signature behavior with mobile movement can be modeled as an
autoregressive process. The coefficients derived from observations of the
uplink spatial signatures can be used to successfully predict the downlink
spatial signatures that follow. The predictions increase the downlink
received power or signal-to-interference ratio, depending on the downlink
beamforming method used, by as much as 10 dB in comparison to beamforming
without prediction. These predictions can be used instead of channel
coding to double the data throughput and allow reliable communication to
two co-channel users traveling as fast as 105 km/h in urban,
non-line-of-site environments. The talk will include the consideration of
issues necessary for the practical implementation of downlink beamforming
with prediction in frequency-division duplex systems.
Biography
Alberto Arredondo began his undergraduate studies at the University of
Texas at Austin in the summer of 1990 and earned his bachelor of science
degree in electrical engineering in August of 1994. He officially
received his master of science degree at the University of California at
Berkeley in December of 1996. He returned to the University of Texas in
the fall of 1996 to pursue doctoral studies under the direction of Prof.
Guanghan Xu. He is the primary author of 2 conference papers, 1 journal
paper, and has 2 manuscripts under review in IEEE Transactions on
Communications. He worked as a technical consultant to Fulbright &
Jaworski, L.L.P. in Austin during 1998 and 1999.
A list of Telecommunications and Signal Processing Seminars is available at
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