How Feedback Improves Coding Performance over Memoryless Channels

Speaker: Prof. Aaron Wagner
Affiliation: Cornell University


We introduce a novel mechanism, called timid/bold coding, by which feedback can be used to improve coding performance over some discrete memoryless channels (DMCs). For a certain class of DMCs, called compound dispersion channels, we show that timid/bold coding allows for an improved second-order coding rate compared with coding without feedback.  For DMCs that are not compound dispersion, we show that feedback does not improve the second-order coding rate; thus, we completely determine the class of DMCs for which feedback improves the second-order coding rate.  An upper bound on the second-order coding is provided for compound-dispersion DMCs. The main results are obtained by relating the analysis of feedback codes to certain controlled diffusions.  [This is joint work with Yucel Altug and Nirmal Shende.]


Aaron Wagner is a professor in the School of Electrical and Computer Engineering at Cornell University. He received the B.S. degree from the University of Michigan, Ann Arbor, and the M.S. and Ph.D. degrees from the University of California, Berkeley. During the 2005-2006 academic year, he was a Postdoctoral Research Associate in the Coordinated Science Laboratory at the University of Illinois at Urbana-Champaign and a Visiting Assistant Professor in the School of Electrical and Computer Engineering at Cornell.  He has received the NSF CAREER award, the David J. Sakrison Memorial Prize from the U.C. Berkeley EECS Dept., the Bernard Friedman Memorial Prize in Applied Mathematics from the U.C. Berkeley Dept. of Mathematics,  the James L. Massey Research and Teaching Award for Young Scholars from the IEEE Information Theory Society and teaching awards at the Department, College, and University level at Cornell.

For more information, contact Prof. Richard D. Wesel ()

Date(s) - May 23, 2019
2:00 pm - 3:00 pm

EE-IV Shannon Room #54-134
420 Westwood Plaza - 5th Flr., Los Angeles CA 90095