Securing massive MIMO at the Physical Layer
Friday, April 15, 2016 - 1:00pm to 2:00pm
Packard 202
Can Emre Koksal (Ohio State University)
Abstract / Description: 

Massive MIMO is one of the highlights of the envisioned 5G communication systems. In the massive MIMO paradigm, the base station is equipped with a number of antennas, typically much larger than the number of users served. While many issues behind the design of multicellular massive MIMO systems have been studied extensively, security of massive MIMO has not been addressed in most part. In this talk, we provide a brief introduction to physical layer security and massive MIMO before we discuss major vulnerabilities of massive MIMO as well as potential defense strategies.

To that end, we consider a single-cell downlink massive MIMO system in the presence of attackers capable of simultaneous jamming and eavesdropping. We show that, classical attacks of data jamming and data eavesdropping can be simultaneously rendered useless: as the number of antennas grow, with proper precoding and power control, mobiles can simultaneously achieve (1) full equivocation without the need to use wiretap encoding under data eavesdropping and (2) no-attack achievable rates under data jamming. However, we introduce a new attack strategy that involves jamming pilot signals and eavesdropping in succession and show significant reductions in the achievable secrecy rate, even in the asymptotic regime in the number of antennas. To counter this attack, we develop a defense strategy in which we use a secret key to encrypt the pilot sequence assignments, rather than encrypt the data. We show that hiding the training signal assignments from the attacker enables the mobiles to achieve secure degrees of freedom, identical to the achievable degrees of freedom under no attack.


Can Emre Koksal received the B.S. degree in Electrical Engineering from the Middle East Technical University in 1996, and the S.M. and Ph.D. degrees from MIT in 1998 and 2002, respectively, in Electrical Engineering and Computer Science. He was a Postdoctoral Fellow at MIT until 2004, and a Senior Researcher at EPFL until 2006. Since then, he has been with the Electrical and Computer Engineering Department at Ohio State University, currently as an Associate Professor. His general areas of interest are wireless communication, communication networks, information theory, stochastic processes, and financial economics.

He is the recipient of the National Science Foundation CAREER Award in 2011, a finalist of the Bell Labs Prize in 2014, the OSU College of Engineering Lumley Research Award in 2011, and the co-recipient of an HP Labs - Innovation Research Award in 2011. The paper he co-authored was a best student paper candidate in MOBICOM 2005. A wireless energy harvesting technology he invented is being commercialized by Nikola Labs and is featured at various outlets including Forbes, Wired, Business Insider, Columbus Dispatch, and NPR. Currently, he is an Associate Editor for IEEE Transactions on Information Theory, IEEE Transactions on Wireless Communications, and Elsevier Computer Networks.