Research

My main research spans information and communication theories, communication for networked control systems, convex optimization and state estimation.

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Information measures and Statistics

In this research, we study various properties of information measures, such as, directed information, causally condition directed information and its variants. We also study the optimal transport problem furnished with an information theoretic constraint and derive upper bounds using tools from functional analysis, measure theory, information geometry etc.

Selected Publications

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Source coding and rate distortion theory

In this research direction, we study generalizations of classical source coding and Shannon's rate distortion theory. We ask questions like, for instance, how source coding and rate distortion theory can be applied to delay-constrained dynamical systems, or what are the performance limitations of block sequential source coding when the receiver decodes the message non-causally?

Selected Publications

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Joint source-channel coding

In this research direction, we study linear and non-linear source-channel coding schemes to achieve optimal or near-optimal performance within a delay constrained point-to-point system or a delay constrained network.?

Selected Publications

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Feedback capacity of channels with memory

In this research direction, we are interested in computing the (ergodic) channel capacity of (finite alphabet) noisy channels with memory and/or feedback. Ergodic feedback capacity is one of the fundamental characterizations in communication theory because it gives theoretical limitations on the least upper bound of allowable rate conveyed through a communication channel. However, characterizing the ergodic channel capacity of a communication system that is often expressed as an intractable optimization problem is not an easy task, let alone finding analytical expressions to such characterizations. In information theory, ergodic channel capacity is computed in closed form expressions for simple memoryless channels (defined either on finite or continuous alphabet spaces) For these simple channel models it is well-known that the presence of noiseless feedback often makes the coding much simpler but it cannot outperform the ergodic channel capacity without noiseless feedback. Unfortunately, this is not the case for channels with memory and, thus, to arrive to similar conclusions as those deduced for the class of memoryless channels, one has to characterize and then find analytical or computable expressions for specific classes of channels with memory.

Selected Publications

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Communication and Coding for Networked Control Systems

In this research direction, we are interested in identifying fundamental performance limitations and practical coding schemes for single closed loop control systems, extensions to problems with side information and to multi-loop closed loop systems which are the epitomy of a networked control system. To do it, we use tools from estimation theory, identification and optimization.

Selected Publications

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Coordination and Cooperation in Network Topologies

In this research direction, we are interested in coordination and cooperation of nodes (or agents) of an abstract network topology. We ask fundamental questions such as, how an agent can coordinate its actions with another agent when they communicate, or, what type of coordination can be established if the communication between two agents is partially lost? There are two types of coordination thus far using information theoretic tools, empirical and strong coordination. Our research is mainly focused in empirical coordination that can be established using modified techniques from source coding theory. In addition, we are also interested in understanding strong coordination because this type of coordination seems more appealing as it takes into account common information between agents which is a fundamental concept to further understand the cooperation between nodes in multi-agent systems.

Selected Publications

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Information Theoretic Privacy/Secrecy for Networks

Information theoretic secrecy comprises of a crypto-system that needs to be studied using information theoretic tools. This encrypted system cannot be broken even if the eavesdropper/adversary has unlimited computing power and is considered crypto-analytically unbreakable if the adversary does not have enough information to break the encryption. The precursor of the concept of information theoretic secure communication was Claude Shannon with his seminal paper back in 1949. After that work many notable researchers tried to understand information theoretic secrecy from different perspectives using different information measures and coding schemes.

Selected Publications

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Strategic Information Transmission/Non-cooperative Games

We use tools from game theory to study non-cooperative communication setups. For instance, we study Nash equilibria and Stackelberg equilibria in a communication setup with a type of side information. For the Nash equilibria there are two individual players (i.e., encoder/decoder) who choose their actions independently to minimize a prespecified cost assigned to each player. For the Stackelberg equilibria the two players cooperate to minimize the prespecified cost.

Selected Publications