Adaptive Chip-Level Channel Estimation for IMT-DS System: DL and UL

In this paper, chip-level adaptive channel estimation has been explored by using LMS algorithm for wideband CDMA channel estimation. The expression for the optimum step-size is modified for fading channel estimation problem. In addition, a new method is proposed to obtain channel estimates with known pilot symbols which is found to give better results than other methods. For slow fading channels, like pedestrian channel, LMS estimator with no update mode is found to give satisfactory results. For fast fading channels, like vehicular channel, a common decision directed technique of channel estimation is modified to be used at chip-level in the downlink (DL). A novel despreader-respreader based channel estimator has been proposed to obtain uplink channel estimates at chip level which resolves the deficiencies of conventional methods. The performance of Rake receiver with proposed channel estimation schemes for IMT-DS system – a 3G mobile communication standard – is evaluated in terms of BER. S. Faisal A. Shah received the B.S. degree from NED University of Engineering and Technology, Karachi, Pakistan, in 1998 and the M.S. degree from King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia, in 2001, both in Electrical Engineering. From 2001 to 2004, he was a Lecturer in Electrical & Electronics Engineering Department, University of Sharjah, UAE. In September 2004, he joined the Electrical and Computer Engineering Department of University of Minnesota, USA, as a research assistant where he is currently pursuing the Ph.D. degree in Electrical Engineering. His research interests include ultra-wideband communication systems, adaptive signal processing and its application to wireless communication systems. Asrar U.H. Sheikh graduated from the University of Engineering and Technology, Lahore, Pakistan with first class honours and received his M.Sc. and Ph.D. degrees from the University of Birmingham, England, in 1966 and 1969 respectively. After completing teaching assignments in several countries, he returned to Birmingham as a Research Fellow in 1975. He worked at Carleton University from 1981 to 1997, first as Associate Professor and later as a Professor and Associate Chairman for Graduate Studies. He was the Founder Director of PCS Research Laboratory at Carleton University. Before taking position of Bugshan/Bell Lab Chair in Telecommunications at King Fahd University of Petroleum and Minerals in April 2000, he was a Professor and Associate Head of the Department of Electronic and Information Engineering at Hong Kong Polytechnic University, where he was founding director of Wireless Information Systems Research (WISR) Centre. At KFUPM he established Telecommunications Research Laboratory. Professor Sheikh is the author of a recently published book, Wireless Communications - Theory & Techniques published by Kluwer Academic Publishers, Orwell, Mass., USA. He has published over 230 papers in international journals and conference proceedings. He also authored or co-authored 30 technical reports. Dr. Sheikh is a co-recipient of Paul Adorian Premium from IERE (London) for his work on impulsive noise characterization. He was awarded teaching achievement awards in 1984 and 1986, and Research Achievement Award in 1994, all by Carleton University. Dr. Sheikh is actively involved in several international conferences mainly as a member of Technical Program Committees. He has organized and chaired many technical sessions at several international conferences. He Chaired the Technical Program of VTC'98. He is an editor of IEEE Transaction on Wireless Communications, a Technical Associate Editor of IEEE Communication Magazine. He is on the Editorial Board of Wireless Personal Communications, and Wireless Communications and Mobile Computing. He was a co-guest editor of the Special Issue of WPC on Interference. Dr. Sheikh is also on the reviewer panels of many IEEE and IEE Transactions and Journals. Dr. Sheikh has been consultant to many private companies and government agencies. His current interests are in signal processing in communications, mitigation of interference, spread spectrum and 3G and beyond systems. His other interests include helping developing countries in education and research. He had assignments under UNDP's sustained Development Program. He is a Fellow of the IEEE and a Fellow of the IEE. Dr. Sheikh is listed in Marquis Who's Whos in the world and Who's Who in Science and Engineering.