Design of Cognitive Radio Systems Under Temperature-Interference Constraints: A Variational Inequality Approach

Daniel P. Palomar, Hong Kong University of Science and Technology (HKUST)


The concept of cognitive radio (CR) has recently received great attention from the research community as a promising paradigm to achieve efficient use of the frequency resource by allowing the coexistence of licensed (primary) and unlicensed (secondary) users in the same bandwidth. We propose a novel Nash equilibrium (NE) problem to model concurrent communications of cognitive secondary users who compete against each other to maximize their information rate. The formulation contains constraints on the transmit power (and possibly spectral masks) as well as aggregate interference tolerable at the primary users' receivers. The coupling among the strategies of the players due to the interference constraints presents a new challenge for the analysis of this class of Nash games that cannot be addressed using the game theoretical models proposed in the literature. For this purpose, we need the framework given by the more advanced theory of finite-dimensional Variational Inequalities (VI). This provides us with all the mathematical tools necessary to analyze the proposed NE problem (e.g., existence and uniqueness of the solution) and to devise alternative distributed algorithms along with their convergence properties.


Biography:  Daniel P. Palomar (S'99-M'03-SM'08) received the Electrical Engineering and Ph.D. degrees (both with honors) from the Technical University of Catalonia (UPC), Barcelona, Spain, in 1998 and 2003, respectively. Since 2006, he has been an Assistant Professor in the Department of Electronic and Computer Engineering at the Hong Kong University of Science and Technology (HKUST), Hong Kong. He has held several research appointments, namely, at King's College London (KCL), London, UK; Technical University of Catalonia (UPC), Barcelona; Stanford University, Stanford, CA; Telecommunications Technological Center of Catalonia (CTTC), Barcelona; Royal Institute of Technology (KTH), Stockholm, Sweden; University of Rome "La Sapienza", Rome, Italy; and Princeton University, Princeton, NJ. His current research interests include applications of convex optimization theory, game theory, and variational inequality theory to signal processing and communications. Dr. Palomar is an Associate Editor of IEEE Transactions on Signal Processing, a Guest Editor of the IEEE Signal Processing Magazine 2010 special issue on "Convex Optimization for Signal Processing," was a Guest Editor of the IEEE Journal on Selected Areas in Communications 2008 special issue on "Game Theory in Communication Systems," as well as the Lead Guest Editor of the IEEE Journal on Selected Areas in Communications 2007 special issue on "Optimization of MIMO Transceivers for Realistic Communication Networks." He serves on the IEEE Signal Processing Society Technical Committee on Signal Processing for Communications (SPCOM). He is a recipient of a 2004/06 Fulbright Research Fellowship; the 2004 Young Author Best Paper Award by the IEEE Signal Processing Society; the 2002/03 best Ph.D. prize in Information Technologies and Communications by the Technical University of Catalonia (UPC); the 2002/03 Rosina Ribalta first prize for the Best Doctoral Thesis in Information Technologies and Communications by the Epson Foundation; and the 2004 prize for the best Doctoral Thesis in Advanced Mobile Communications by the Vodafone Foundation and COIT.