@article{3373973c01ef4b3b9abbb330e654ae3f,

title = "Game theory and power control in ultrawideband networks",

abstract = "This paper describes a theoretical framework for the design and analysis of power control algorithms for high-throughput wireless networks using ultrawideband (UWB) technologies. The tools of game theory are shown to be expedient for deriving scalable, energy-efficient, distributed power control schemes to be applied to a population of battery-operated user terminals in a rich multipath environment. In particular, the power control issue is modeled as a dynamic noncooperative game in which each user chooses its transmit power so as to maximize its own utility, which is defined as the ratio of throughput to transmit power. Although distributed (noncooperative) control is known to be suboptimal with respect to the optimal centralized (cooperative) solution, it is shown via large-system analysis that the game-theoretic distributed algorithm based on Nash equilibrium exhibits negligible performance degradation with respect to the centralized socially optimal configuration. The framework described here is general enough to also encompass the analysis of code division multiple access (CDMA) systems and to show that UWB slightly outperforms CDMA in terms of achieved utility at the Nash equilibrium.",

keywords = "Energy efficiency, Frequency-selective multipath, Game theory, Impulse radio, Large-system analysis, Nash equilibrium, Power control, Ultrawideband",

author = "Giacomo Bacci and Marco Luise and Poor, {H. Vincent}",

note = "Funding Information: In this paper, we have shown how to formulate the distributed power control problem in the uplink of a (large) IR-UWB wireless network in terms of game theory. The main concern in the identification of the game is power efficiency. This leads us to the use of a utility function that maximizes the life of a battery-operated terminal: the ratio between the correctly delivered bits in a packet versus the energy spent to deliver those bits. When each user adopts a best-response strategy, which consists of updating its transmit power according to the throughput obtained at the access point, all users achieve a unique stable equilibrium from which no terminal wishes to unilaterally deviate (the Nash equilibrium). Our large-system analysis suggests that this happens irrespective of the statistics of the channel taps (assuming a tapped-delay line model), and of the kind of Rake receiver that is adopted at the access point to cope with multipath propagation. Such analysis is fairly general and captures a few different scenarios: the wireless channel can be either frequency-selective with exponential decay, or frequency-flat, or frequency-selective with flat power delay profile; the receiver can be either partial- or all-Rake with maximal ratio combining. Our (closed-form) result for the distributed power control can be compared with the optimal power allocation in a social sense, which corresponds to a centralized solution under the control of the access point. The typical degradation in terms of energy efficiency of distributed control with respect to such an optimum turns out to be negligible. This paves the way for the use of game-theoretic power control techniques in wireless networks when energy efficiency is the main concern. We also have shown that our framework and the relevant conclusions are further applicable to classical random CDMA, which pays only a small degradation in terms of achieved utility with respect to IR-UWB. The resource allocation schemes presented in this overview can be further refined by considering mixed strategies , where the user terminals choose their transmit powers according to an optimal probability distribution . This introduces additional signal processing at the mobile terminal, which however does not represent a technological limit. On the other hand, enlarging the set of allowable powers might increase the potentiality of the power control algorithm. An alternative approach to pure energy-efficiency-driven control would be replacing the goodput of the link with its Shannon capacity [19] , assuming that the terminal uses adaptive coding and modulation (ACM) to stay as close as possible to capacity for each channel condition. Further benefits can be provided by devising more elaborate cross-layer optimizations, which consider other aspects of the network. As an example, medium access control (MAC) schemes can also be considered as part of a more general resource allocation strategy due to the competitive (and hence game-theoretic) nature of the medium contention. Some results along these lines are found in [37] . If power allocation is designed jointly with the MAC strategy according to the utility-maximizing criteria described above, more effective resource allocation is guaranteed to all the terminals in the network. Giacomo Bacci received the B.E. and the M.E. degrees in telecommunications engineering from the University of Pisa, Pisa, Italy, in 2002 and 2004, respectively. He is currently working toward the Ph.D. degree in information engineering at the same university. Since 2005, he has been with the Department of Information Engineering at the University of Pisa. In 2006, he was a visiting student research collaborator at the Department of Electrical Engineering at Princeton University, Princeton, NJ. His research interests are in the areas of digital communications, signal processing and estimation theory. His current research topics focus on power control for multiple-access wireless networks and time delay estimation for satellite positioning systems and wireless communications. Marco Luise is a Full Professor of Telecommunications at the University of Pisa, Italy. After receiving his M.E. and Ph.D. degrees in electronic engineering from the University of Pisa, he was a Research Fellow of the European Space Agency (ESA) at ESTEC Noordwijk, The Netherlands, and a Researcher of the Italian National Research Council (CNR), at the CSMDR Pisa. Prof. Luise co-chaired four editions of the Tyrrhenian International Workshop on Digital Communications, was the General Chairman of the URSI Symposium ISSSE{\textquoteright}98, and the General Chairman of EUSIPCO 2006 in Florence, Italy. Prof. Luise is a Senior Member of the IEEE and served as an Editor for Synchronization of the IEEE Transactions on Communications , and as an Editor for Communications Theory of the European Transactions on Telecommunications. He is the co-Editor-in-Chief of the recently founded International Journal of Navigation and Observation, and acts as the General Secretary of the Italian Association GTTI, Gruppo Telecomunicazioni Teoria dell{\textquoteright}Informazione. He has authored more than 150 publications on international journals and contributions to major international conferences, and holds a few international patents. His main research interests lie in the area of wireless communications, with particular emphasis on CDMA/multicarrier signals and satellite communications and positioning. H. Vincent Poor received the Ph.D. degree in EECS from Princeton University in 1977. From 1977 until 1990, he was on the faculty of the University of Illinois at Urbana-Champaign. Since 1990 he has been on the faculty at Princeton, where he is the Michael Henry Strater University Professor of Electrical Engineering and Dean of the School of Engineering and Applied Science. Dr. Poor{\textquoteright}s research interests are in the areas of stochastic analysis, statistical signal processing and their applications in wireless networks and related fields. Among his publications in these areas is the recent book MIMO Wireless Communications (Cambridge University Press, 2007). Dr. Poor is a member of the National Academy of Engineering, a Fellow of the American Academy of Arts and Sciences, and a former Guggenheim Fellow. He is also a Fellow of the IEEE, the Institute of Mathematical Statistics, the Optical Society of America, and other organizations. In 1990, he served as President of the IEEE Information Theory Society, and in 2004–07 he served as the Editor-in-Chief of the IEEE Transactions on Information Theory . Recent recognition of his work includes the 2005 IEEE Education Medal and the 2007 IEEE Marconi Prize Paper Award. ",

year = "2008",

month = mar,

doi = "10.1016/j.phycom.2008.01.004",

language = "English (US)",

volume = "1",

pages = "21--39",

journal = "Physical Communication",

issn = "1874-4907",

publisher = "Elsevier",

number = "1",

}