The Role of Feedback in Communication

Speaker: Young-Han Kim,
UC San DiegoAbstract: Many common communication situations are over inherently two-way channels, such as telephone systems, digital subscriber lines (DSL), cellular networks, and the Internet. In fact, even ``point-to-point'' systems, where the end goal is to transfer information in one direction, often give rise to two-way communication scenarios due to the presence of feedback. In such systems, one can receive feedback from the other end of the channel, which can be used to improve the quality of communication. Although feedback is present in many communication systems, and is being used in certain primitive forms as in channel estimation and automatic repeat request (ARQ), the theory behind its use is far from complete.In this talk, we focus on two recent findings in information theory to discuss the role of feedback in communication networks. Our first result characterizes the feedback capacity of nonwhite Gaussian channels, answering a long-standing open problem studied by many researchers, and shows how dramatic performance improvements can be achieved with optimal use of feedback. Our second result proposes an efficient and robust coding method for more realistic systems with noisy feedback. Although this coding method is still at a conceptual level, it brings up a new paradigm of cross-layer design.Based on joint work with Tsachy Weissman and Amos Lapidoth.Biography: Young-Han Kim is an assistant professor in the Department of Electrical and Computer Engineering at the University of California, San Diego. Professor Kim's research primarily focuses on network information theory and the role of feedback in communication networks.
More broadly, he is interested in statistical signal processing and information theory, with applications in communication, control, computation, networking, data compression, and learning.Professor Kim received his B.S. degree with honors in Electrical Engineering from Seoul National University, in 1996, where he was a recipient of the General Electric Foundation Scholarship. After a three-and-half-year stint as a software architect at Tong Yang Systems, Seoul, Korea, working on several industry projects such as developing the communication infrastructure for then newly opening Incheon International Airport, he resumed his graduate studies at Stanford University, and received his Ph.D. degree in Electrical Engineering (M.S. degrees in Statistics and in Electrical Engineering) in 2006. Professor Kim is a recipient of the 2008 NSF Faculty Early Career Development (CAREER) Award. Host: Urbashi Mitra, ubli@usc.edu, EEB 540, x04667

Location: Frank R. Seaver Science Center (SSC) - 319

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos