Toronto
Networking Seminar 2006
Wireless
Network Information Theory
LiangLiang
Xie
University of Waterloo
Date:
February 3, 3pm
Location: BA1210 (Bahen Center)
Abstract
How
much information can a wireless network with a multiplicity of nodes
transport, and how should the nodes cooperate to transfer information?
We are interested in the best throughput performance a wireless network
can achieve. For this, one naturally turns to the field of information
theory. However, network information theory for communication channels
with multiple users is an area where even several simplest scenarios,
such as the interference channel and the relay channel, have not been
completely solved.
We formulate a model of wireless networks that particularly takes into
account the distances between nodes, and the resulting attenuation of
radio signals, and study a performance measure, the transport capacity,
that weights information by the distance over which it is transported.
We show that there is a dichotomy
between the regimes of high and low signal attenuations. In the high
signal attenuation regime, the transport capacity is bounded by a
constant multiple of the sum of the transmit powers of all the nodes in
the network. If the nodes are individually power limited, the transport
capacity consequently scales as O(n), where n is the number of nodes in
the network. However, in the low signal attenuation regime, there exist
networks that can provide unbounded transport capacity, even for fixed
total power. Moreover, there are special networks that can even attain
superlinear scaling. These examples show
that nodes can profitably cooperate over large distances using
coherence and multiuser estimation when the attenuation is low.
We
conclude with some open issues.
Bio:
Dr.
Xie is currently an Associate Professor at the Department of Electrical
and Computer Engineering, University of Waterloo. He received
the B.S. degree in mathematics from Shandong University, China and the
Ph.D. degree in control theory from the Chinese Academy of Sciences in
1995 and 1999, respectively. He was a Guest Researcher in the Automatic
Control Group, Linköping University, Sweden during 19992000
and a Postdoctoral Research Associate in the Coordinated Science
Laboratory, University of Illinois at UrbanaChampaign, USA during
20002002.
