Date: February 3, 2006

Time: 3:00 p.m.

Location: Centergy One 5186

Speaker(s): Dr. Xiaoli Ma

Title: Channel Shortening Equalization for Differential OFDM Systems

Abstract:
In orthogonal frequency division multiplexing (OFDM) systems, the length of cyclic prefix (CP) has to be greater than the length of channel impulse response to avoid inter-block interference. Not long enough CP degrades the system performance dramatically. However, a long CP costs extra bandwidth and reduces power efficiency. On the other hand, excessive training and blind estimation for long channels may cost extra bandwidth and computational complexity. This paper designs a channel shortening filter for differential OFDM systems through unknown multipath channels with long delay spreads. Without introducing extra redundancy, we design a low-complexity but efficient channel shortening equalizer (CSE). Our design bypasses the channel estimation, and improves bandwidth and power efficiencies. Adaptive CSE is also proposed when the channel is slow time-varying. Our design is easy to be implemented at both transmitter and receiver. Simulation results corroborate the merits of our design.

Bio:
Dr. Ma received the B.S. degree in Automatic Control from Tsinghua University, Beijing, China in 1998, the M.S. degree in Electrical Engineering from the University of Virginia in 2000, and the Ph.D. degree in Electrical Engineering from the University of Minnesota in 2003. After receiving her Ph.D., she joined the Department of Electrical and Computer Engineering at Auburn University, where she served as an assistant professor until 2005. Since spring 2006, she has been with the School of Electrical and Computer Engineering at Georgia Tech.

Date:	February 3, 2006
Time:	3:00 p.m.
Location:	Centergy One 5186
Speaker(s):	Dr. Xiaoli Ma
Title:	Channel Shortening Equalization for Differential OFDM Systems
Abstract:	In orthogonal frequency division multiplexing (OFDM) systems, the length of cyclic prefix (CP) has to be greater than the length of channel impulse response to avoid inter-block interference. Not long enough CP degrades the system performance dramatically. However, a long CP costs extra bandwidth and reduces power efficiency. On the other hand, excessive training and blind estimation for long channels may cost extra bandwidth and computational complexity. This paper designs a channel shortening filter for differential OFDM systems through unknown multipath channels with long delay spreads. Without introducing extra redundancy, we design a low-complexity but efficient channel shortening equalizer (CSE). Our design bypasses the channel estimation, and improves bandwidth and power efficiencies. Adaptive CSE is also proposed when the channel is slow time-varying. Our design is easy to be implemented at both transmitter and receiver. Simulation results corroborate the merits of our design.
Bio:	Dr. Ma received the B.S. degree in Automatic Control from Tsinghua University, Beijing, China in 1998, the M.S. degree in Electrical Engineering from the University of Virginia in 2000, and the Ph.D. degree in Electrical Engineering from the University of Minnesota in 2003. After receiving her Ph.D., she joined the Department of Electrical and Computer Engineering at Auburn University, where she served as an assistant professor until 2005. Since spring 2006, she has been with the School of Electrical and Computer Engineering at Georgia Tech.