[CPCC] TALK: New Results in Multi-User Information Theory Thu 10/18 1 PM

Ender Ayanoglu ayanoglu at uci.edu
Tue Oct 16 15:59:16 PDT 2007


                                TALK

        Degrees of Freedom of Wireless Interference Networks

                                by

                        Prof. Syed A. Jafar
                             EECS Dept
              The Henry Samueli School of Engineering
                             UC Irvine

                     October 18, 2007, Thursday
                             1-2:30 PM
                       Engineering Tower 331


                              Abstract

The talk will present new insights into the capacity of fully
connected wireless networks with finite number of nodes through
capacity approximations that are accurate to within a bounded constant
for all SNR.  While the best known outerbound for the K user
interference channel states that there cannot be more than K/2 degrees
of freedom, it has been conjectured that in general the constant
interference channel with any number of users has only one degree of
freedom. In this talk, we show that K/2 degrees of freedom can be
achieved by channel design, i.e., if the nodes are allowed to choose
the best constant, finite and non-zero channel coefficient
values. Even if channel coefficients cannot be controlled by the nodes
but are selected by nature, i.e., randomly drawn from a continuous
distribution, the total number of spatial degrees of freedom for the K
user interference channel is almost surely K/2 per orthogonal time and
frequency dimension. In other words we will show how to achieve K/2
interference free channels per time and frequency dimension in a K
user interference network of single antenna nodes. Thus, only half the
spatial degrees of freedom are lost due to distributed processing of
transmitted and received signals on the interference channel. We will
also characterize the benefits of cognitive message sharing among
nodes from a degrees of freedom perspective.


                        Speaker's Biography

Syed Ali Jafar received the B. Tech. degree in Electrical Engineering
from the Indian Institute of Technology (IIT), Delhi, India in 1997,
the M.S.  degree in Electrical Engineering from California Institute
of Technology (Caltech), Pasadena USA in 1999, and the Ph.D. degree in
Electrical Engineering from Stanford University, Stanford, CA USA in
2003. His industry experience includes positions at Lucent Bell Labs,
Qualcomm Inc., and Hughes Software Systems. He is currently an
Assistant Professor in the Department of Electrical Engineering and
Computer Science at the University of California Irvine, Irvine, CA
USA. His research interests include multiuser information theory and
wireless communications. Dr.  Jafar received the NSF CAREER award and
the UC Irvine Engineering Faculty of the Year award in 2006. Dr. Jafar
serves as the Editor for Wireless Communication Theory and CDMA for
the IEEE Transactions on Communications.



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