Shannon meets von Neumann

Ankur A. Kulkarni
Vinod M. Prabhakaran
Tuesday, 17 Sep 2019, 14:30 to 15:30
A-201 (STCS Seminar Room)
Abstract: Networked systems like the Internet of Things are everywhere, transmitting sensitive information over media that are susceptible to variability or eavesdropping. How does one securely transmit information when the channel could be controlled by a malicious jammer? The solutions traditionally sought by information theorists have concentrated on what the communication system can achieve in the worst case over all possible scenarios; we call this the Shannon solution. However, one could also study this problem from the vantage point of a game between the communication system and the jammer and employ solution concepts from game theory to ‘solve’ the game and analyze the system; we refer to the resulting solution as the von Neumann solution. Thinking about the problem this way forces us to confront these two seemingly different perspectives and ask if they are compatible. While a Shannon solution always exists, we find that a von Neumann solution need not due inherent nonconvexities in the problem. And even both exist, do their answers coincide? If they don't, it may warrant revisiting some age-old notions.
We find that despite many reasons to be skeptical, the problem admits elegant solutions in the large blocklength limit, and in this limit the Shannon solution comes in harmony with the von Neumann solution. We show this for two models - one where the jammer's action does not change along the transmission and one where it does.
This is joint work with Ph.D. students Sharu Theresa Jose (now graduated) and Anuj Vora.
Bio: Ankur is an Associate Professor with the Systems and Control Engineering group at Indian Institute of Technology Bombay (IITB). He received his B.Tech. from IITB in 2006, followed by M.S. in 2008 and Ph.D. in 2010, both from the University of Illinois at Urbana-Champaign (UIUC). From 2010-2012 he was a post-doctoral researcher at the Coordinated Science Laboratory at UIUC. His research interests include information theory, the role of information in stochastic control, game theory, combinatorial coding theory problems, optimization and variational inequalities, and operations research. He is an Associate (from 2015–2018) of the Indian Academy of Sciences, Bangalore, a recipient of the INSPIRE Faculty Award of the Department of Science and Technology, Government of India, 2013, Best paper awards at the National Conference on Communications, Chennai, 2017, and Indian Control Conference 2018, runner up best paper award at the International Conference on Signal Processing and Communication (SPCOM), Bengaluru, 2018, Excellence in Teaching Award 2018 at IITB and the William A. Chittenden Award, 2008 at UIUC. He was a consultant to the Securities and Exchange Board of India on regulation of high frequency trading.