Modeling and Mitigation of Time- and Frequency-Selective
Fading in Single- and Multi-Carrier Communications
Mr. Cihan Tepedelenlioglu
Dept. of Electrical and Computer Engineering
University of Minnesota
Minneapolis, Minnesota
Thursday, March 29th, 11:00 AM, ENS 637
cihan@ece.umn.edu
Abstract
The tremendous growth of wireless industry along with the limitations of its
resources has made modeling and mitigation of the wireless channel a subject
of paramount importance. Specifically, joint mitigation of time-selective and
frequency-selective fading is an important and challenging problem in mobile
communications. Relying on transmitter-induced redundancy using filterbanks,
we have developed novel channel estimation and symbol recovery approaches for
blind identification and equalization of time- and frequency-selective channels
where the time variation is modeled deterministically by a basis expansion.
The resulting algorithms enable the usage of a single antenna, dispense with
channel disparity conditions of existing approaches, and allow channel order
overestimation.
Towards the goal of modeling and mitigation of fading channels, estimation of
the statistical channel parameters is also needed. These parameters include,
local average power, maximum Doppler spread, the Ricean K factor, shadow
variance and correlation distance, all of which are crucial in assessing link
quality in wireless systems. We have developed novel estimators for these
parameters, and assessed their performance using analytical tools.
The ability of OFDM systems to mitigate frequency-selective channels is also
impaired by the presence of a carrier frequency offset (CFO), which is a form
of time-selectivity. We have developed a matrix-vector framework for OFDM
systems with CFOs in baseband, and used this framework in developing new
approaches for CFO estimation that do not suffer from the lack of
identifiability problems of current schemes.
Biography
Mr. Cihan Tepedelenlioglu is a graduate student with the Communication and
Signal Processing Laboratory at University of Minnesota under Prof. Georgios
B. Giannakis. His general interests lie in the area of modeling and
equalization of time- and frequency- selective fading channels, and
time-varying systems. Recently, he has been investigating how precoding at
the input can help in blind identification / equalization problems for
fading channels.
A list of Telecommunications and Signal Processing Seminars is available at
from the ECE department Web pages under "Seminars".
The Web address for the Telecommunications and Signal Processing Seminars is
http://anchovy.ece.utexas.edu/seminars