Events Calendar

Unique Word Prefix OFDM: An Overview

Speaker: Prof. Dr.-Ing. habil. Johannes Huber, University of Erlangen-Nuremberg

Talk Title: Unique Word Prefix OFDM: An Overview

Abstract: In unique word OFDM (UW-OFDM), cyclic prefixes (CP) of usual OFDM are replaced by a deterministic sequence, the unique word (UW), for conversion of linear convolution due to a dispersive channel into cyclic convolution. This fixed UW may be employed for synchronization and/or channel estimation purposes etc. at the receiver side. In order to generate space for the UW, a block of zeros is created in time domain by means of appropriately loading of redundant subcarriers. By this, a systematic complex number Reed Solomon (RS) code construction is inherently introduced along the subcarriers which additionally can be exploited at the receiver by means of Bayesian linear data estimation (LMMSE) or decision-directed methods (SIC, Noise Prediction). A remaining problem in the UW-OFDM concept is the fact that the energy on the redundant subcarrier symbols contributes disproportionately to average symbol energy. Two methods for a reduction of this redundant energy are proposed, i.e. allowing some small systematic noise in the guard interval and spreading of redundant energy over all subcarrier symbols by which a nonsystematic complex number RS code construction is introduced. Numerical results and comparisons to usual CP-OFDM are presented for the example 802.11a WLAN standard which illustrate benefits of UW-OFDM.

Biography: Johannes Huber received the Dipl.-Ing. degree in electrical engineering from the Technische Universität München, Munich, Germany in 1977. From 1977 to 1982 he was research assistant at the Lehrstuhl für Nachrichtentechnik of the Universität der Bundeswehr München, Munich, from which he received the Dr.-Ing. degree with a thesis on coding for channels with memory. From 1982 to 1990, he was an Akademischer Oberrat at the Universität der Bundeswehr München, Munich and received the Dr.-Ing. habil. degree with a thesis on trellis coded modulation. In 1991 he joined the IBM Research Laboratory, Zurich, Switzerland. He is currently a Professor at the Friedrich-Alexander-University Erlangen-Nuremberg, Germany. He is a former: dean for student affairs, chairman of the department of electrical, electronic, and communication engineering and dean of the Technical Faculty. Dr. Huber is a Fellow of the IEEE, has served two terms on the Board of Governors for the IEEE Information Theory Society (1999-2001,2004-2006. In 2008, he was appointed a corresponding fellow of the Royal Society of Edinburgh. Since 2009, Dr. Huber is an ordinary fellow of the Bavarian Academy of Sciences and Humanities. Dr. Huber has held editorial positions for the IEEE Transactions on Communications and the International Journal on Electronics and Communications for which he has also served as editor-in-chief. Johannes Huber is author and co-author of textbooks on trellis coding and information combining. He has published more than 220 papers in international journals or conference records. Papers authored or co-authored by Johannes Huber were awarded the best paper award of the German Society of Information Technology (ITG) in 1988, 2000, and 2006. He received the Vodafone award for innovations in mobile communications 2004.

Host: Prof. Urbashi Mitra, ubli@usc.edu, x04667

Location: Henry Salvatori Computer Science Center (SAL) - 222

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos