Summary of Activities/Interests
Research Interests: (i) The Analysis and Design of Graph-Based Codes (supported by NSF): This research focuses on the physical layer of digital communication system design � in particular on the analysis, design, and implementation of capacity-approaching low-density parity-check (LDPC) codes for practical communication environments. In the last ten years, the area of channel coding has undergone a revolutionary change with the growing popularity of graph-based codes and iterative decoding algorithms. These coding methods, which include both turbo codes and LDPC codes, approach the limits of channel coding performance promised by Shannon in his landmark 1948 paper. Currently, these codes are in the process of replacing conventional error control techniques in numerous digital communication and storage standards, including, among others, deep-space communication, next-generation wireless transmission, last-mile cable transmission, digital video broadcasting, and high-density digital magnetic recording. The research addresses several issues related to graph-based codes. In particular, it focuses on the analysis, design, and implementation of LDPC convolutional codes, which have several advantages compared to LDPC block codes, but have not received much attention from the research community. Conventional convolutional codes, on the other hand, have had a transformative effect in numerous practical communication environments, and the same is likely to be true in the capacity-approaching world of LDPC codes. We emphasize bridging the gap between advanced theoretical research and realistic practical implementations. In particular, we are concerned with adapting LDPC convolutional code designs to various industry standards that require flexibility in both frame length and code rate and with developing VLSI implementations of hardware decoders that can be tested under real operating conditions. (ii) Distributed Error-Correction Strategies in Wireless Networks (supported by NSF): Networked wireless communications over multiple hops is rapidly emerging as the main architecture of future wireless systems, including multihop extensions of cellular and WiFi networks, mesh networks, and sensor networks. Common among these types of networks is that they are not completely unstructured (or ad hoc) networks, but traffic is routed and accumulated towards a common destination. Due to this characteristic property, we refer to such networks as Networks with Traffic Accumulation, or NETAs. Traffic accumulation creates hot spots or bottlenecks around the common destination because of the increased traffic load and interference. Despite the severity of the hot spot problem, no efficient strategies to cope with it have been proposed in the literature. This research addresses the hot spot issue in NETAs by developing new distributed error correction strategies tailored to two important subclasses - line networks and tree networks. In line networks, we investigate distributed channel coding protocols using serially concatenated and protograph-based constructions to strengthen the error correction capability near the destination without sacrificing bandwidth efficiency. Both the fundamental properties and the design of such protocols are considered. In tree networks, several source nodes may wish to employ a common relay node to broadcast their information to multiple destination nodes, which may also have access to side information from overheard source messages. We explore a novel approach, where each source uses a distinct low rate code for transmission to the relay, and decoded messages are re-encoded using a high rate nested code. In addition, interlayer issues are considered, in particular the joint design of efficient channel access and routing schemes together with the proposed coding schemes. (iii) Low Latency Code Design for Satellite Communications (supported by NASA): The goals of this research are to investigate low latency code designs in support of NASA�s digital satellite communication systems. Preliminary work has established that, for decoding latencies less than a few thousand information symbols, conventional non-iterative decoding techniques, such as Viterbi decoding or sequential decoding of large constraint length convolutional codes, will outperform modern iterative decoding techniques based on low-density parity-check codes. However, this preliminary study considered only code rates of 1/2 and decoded bit-error-rates of 10-4. In this study, we are investigating the tradeoffs between iterative and non-iterative decoding techniques on a broader scale. In particular, we intend to identify code designs and associated decoding methods to achieve a fixed latency constraint for a variety of code rates and performance specifications. Our goal is to provide NASA with the best overall coding strategies to employ in low latency applications. We are focusing our research effort on the additive white Gaussian noise channel model most commonly encountered in satellite communication.
Ph.D., University of Notre Dame, 1969
Daniel J. Costello, Jr. was born in Seattle, WA, on August 9, 1942. He received the B.S.E.E. degree from Seattle University, Seattle, WA, in 1964, and the M.S. and Ph.D. degrees in electrical engineering from the University of Notre Dame, Notre Dame, IN, in 1966 and 1969, respectively. In 1969 he joined the faculty of the Illinois Institute of Technology, Chicago, IL, as an Assistant Professor of Electrical Engineering. He was promoted to Associate Professor in 1973, and to Full Professor in 1980. In 1985 he became Professor of Electrical Engineering at the University of Notre Dame, Notre Dame, IN, and from 1989 to 1998 served as Chairman of the Department of Electrical Engineering. He also was a Research Associate at Cornell University (Summer 1971) and a Visiting Professor at Notre Dame (1983-84), the Swiss Federal Institute of Technology (Spring 1995), the University of Hawaii (Fall 1998), and the Technical University of Munich (Summer/Fall 2001, Summer 2003, Summer 2005). He has served as a professional consultant for Western Electric, Illinois Institute of Technology Research Institute, Motorola Communications, Digital Transmission Systems, Tomorrow, Inc., and Kirkland and Ellis. In 1991, he was selected as one of 100 Seattle University alumni to receive the Centennial Alumni Award in recognition of alumni who have displayed outstanding service to others, exceptional leadership, or uncommon achievement. In 1999, he received a Humboldt Research Prize from the Alexander von Humboldt Foundation in Germany. In 2000, he was named the Leonard Bettex Professor of Electrical Engineering at Notre Dame. Dr. Costello has been a member of IEEE since 1969 and was elected Fellow in 1985. Since 1983, he has been a member of the Information Theory Society Board of Governors on three separate occasions, and in 1986 he served as President of the BOG. From 1992-1995 he was Chair of the Conferences and Workshops Committee and from 2001-2002 Chair of the Fellows Committee of the BOG. He has also served as Associate Editor for Communication Theory for the IEEE Transactions on Communications, as Associate Editor for Coding Techniques for the IEEE Transactions on Information Theory, and as Co-Chair of the IEEE International Symposia on Information Theory in 1988 in Kobe, Japan, in 1997 in Ulm, Germany, and in 2004 in Chicago, IL. In 2000, he was selected as a recipient of an IEEE Third Millennium Medal. He was co-recipient of the 2009 IEEE Donald G. Fink Prize Paper Award, which recognizes an outstanding survey, review, or tutorial paper in any IEEE publication issued during the previous calendar year. Dr. Costello's research interests are in the area of digital communications, with special emphasis on error control coding and coded modulation. He has numerous technical publications in his field, and in 1983 co-authored a textbook entitled "Error Control Coding: Fundamentals and Applications", the 2nd edition of which was published in 2004.