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213
Decentralized Dynamic Spectrum Access for Cognitive Radios: Cooperative Design of a Noncooperative Game
 IEEE TRANSACTIONS ON MOBILE COMUPTING
, 2009
"... We consider dynamic spectrum access among cognitive radios from an adaptive, game theoretic learning perspective. Spectrumagile cognitive radios compete for channels temporarily vacated by licensed primary users in order to satisfy their own demands while minimizing interference. For both slowly v ..."
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Cited by 28 (2 self)
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We consider dynamic spectrum access among cognitive radios from an adaptive, game theoretic learning perspective. Spectrumagile cognitive radios compete for channels temporarily vacated by licensed primary users in order to satisfy their own demands while minimizing interference. For both slowly varying primary user activity and slowly varying statistics of “fast” primary user activity, we apply an adaptive regret based learning procedure which tracks the set of correlated equilibria of the game, treated as a distributed stochastic approximation. This procedure is shown to perform very well compared with other similar adaptive algorithms. We also estimate channel contention for a simple CSMA channel sharing scheme.
Hierarchical SIR and Rate Control on the Forward Link for CDMA Data Users under Delay and Error Constraints
, 2001
"... In this paper, we study SIR and rate control for CDMA data users on the forward link under average or peak power constraints. The QoS for data users is specified by delay and error rate constraints as well as a family of utility functions representing the throughput and fairness among the data users ..."
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Cited by 27 (1 self)
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In this paper, we study SIR and rate control for CDMA data users on the forward link under average or peak power constraints. The QoS for data users is specified by delay and error rate constraints as well as a family of utility functions representing the throughput and fairness among the data users. It is found that the optimal SIR and rate control algorithm has an hierarchical structure which can be easily implemented in a distributed manner. The SIR targets can be adjusted independently by the mobiles using information specific to the individual users. The data rates can be adjusted jointly by the base station based on limited feedback from the mobiles. We also propose a 2level iteration algorithm for both the mobile and the base station to efficiently compute the SIR and data rates. Our results show that a flexible tradeoff between total system throughput (sum of rates achieved) and fairness (similarity in data rates) can be achieved by choosing appropriate utility functions used in this scheme.
Robust Modeling and Analysis for Wireless Data Resource Management
, 2003
"... Recent publications recognize that decentralized algorithms useful in wireless data applications can be obtained via microeconomics and game theory. In these studies, each agent maximizes, under appropriate rules and constraints, a qualityofservice (QoS) index. A key solution concept is a "Na ..."
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Cited by 26 (13 self)
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Recent publications recognize that decentralized algorithms useful in wireless data applications can be obtained via microeconomics and game theory. In these studies, each agent maximizes, under appropriate rules and constraints, a qualityofservice (QoS) index. A key solution concept is a "Nash equilibrium"; i.e., an allocation from which no agent is better off by unilaterally "deviating". The actual maximization may be made by software which may not be directly "controllable" by a human user. The model and, especially, the chosen QoS index should be as general as possible, so that the derived results be applicable to a wide variety of channel conditions, modulation schemes, and other physicallayer characteristics. Likewise, the chosen index should exhibit predictable and reliable technical behavior, without exacting a high complexity cost. This note describes a model, and particularly, a QoS index which can accommodate a wide variety of physical layer situations. The proposed index is shown to exhibit solid technical behavior, be physically significant, intuitively appealing, and applicable to a wide variety of physical layer situations. A game in which terminals carrying multirate traffic seek to maximize this index is analyzed, and closedform equilibrium conditions and power levels are derived "from first principles". All terminals want the same signaltointerference ratio (SIR), but some cannot reach the necessary power level. At equilibrium, a number of terminals transmit at full power, and others achieve the same optimal SIR. A basic rationale to search for these equilibria is provided.
EnergyEfficient Precoding for MultipleAntenna Terminals
, 2011
"... The problem of energyefficient precoding is investigated when the terminals in the system are equipped with multiple antennas. Considering static and fastfading multipleinput multipleoutput (MIMO) channels, the energyefficiency is defined as the transmission rate to power ratio and shown to be ..."
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Cited by 26 (10 self)
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The problem of energyefficient precoding is investigated when the terminals in the system are equipped with multiple antennas. Considering static and fastfading multipleinput multipleoutput (MIMO) channels, the energyefficiency is defined as the transmission rate to power ratio and shown to be maximized at low transmit power. The most interesting case is the one of slow fading MIMO channels. For this type of channels, the optimal precoding scheme is generally not trivial. Furthermore, using all the available transmit power is not always optimal in the sense of energyefficiency [which, in this case, corresponds to the communicationtheoretic definition of the goodputtopower (GPR) ratio]. Finding the optimal precoding matrices is shown to be a new open problem and is solved in several special cases: 1. when there is only one receive antenna; 2. in the low or high signaltonoise ratio regime; 3. when uniform power allocation and the regime of large numbers of antennas are assumed. A complete numerical analysis is provided to illustrate the derived results and stated conjectures. In particular, the impact of the number of antennas on the energyefficiency is assessed and shown to be significant.
Power Allocation Games for MIMO Multiple Access Channels with Coordination
, 2009
"... A game theoretic approach is used to derive the optimal decentralized power allocation (PA) in fast fading multiple access channels where the transmitters and receiver are equipped with multiple antennas. The players (the mobile terminals) are free to choose their PA in order to maximize their indiv ..."
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Cited by 26 (19 self)
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A game theoretic approach is used to derive the optimal decentralized power allocation (PA) in fast fading multiple access channels where the transmitters and receiver are equipped with multiple antennas. The players (the mobile terminals) are free to choose their PA in order to maximize their individual transmission rates (in particular they can ignore some specified centralized policies). A simple coordination mechanism between users is introduced. The nature and influence of this mechanism is studied in detail. The coordination signal indicates to the users the order in which the receiver applies successive interference cancellation and the frequency at which this order is used. Two different games are investigated: the users can either adapt their temporal PA to their decoding rank at the receiver or optimize their spatial PA between their transmit antennas. For both games a thorough analysis of the existence, uniqueness and sumrate efficiency of the network Nash equilibrium is conducted. Analytical and simulation results are provided to assess the gap between the decentralized network performance and its equivalent virtual multiple input multiple output system, which is shown to be zero in some cases and relatively small in general.
Balancing Supply and Demand of Bandwidth in Wireless Cellular Networks: Utility Maximization over Powers and Rates
 in Proc. IEEE INFOCOM
, 2004
"... In wireless cellular networks and wireless local area networks, nonlinear network utility maximization need to be conducted over both user rates and transmit powers. For each of the three cases considered in this paper, we present an algorithm that converges to the jointly optimal pair of rate vecto ..."
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Cited by 24 (1 self)
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In wireless cellular networks and wireless local area networks, nonlinear network utility maximization need to be conducted over both user rates and transmit powers. For each of the three cases considered in this paper, we present an algorithm that converges to the jointly optimal pair of rate vector and power vector. For the simple case when data rates are not limited by interferences, for example in singlecell downlink transmissions, Algorithm 1 we propose is an iterative bidding mechanism between the base station and mobile users, where knowledge about channel conditions and individual user utility functions is only needed locally at each user but not needed at the base station.
Convergence theorem for a general class of power control algorithms
 IEEE Transactions on Communications
, 2004
"... Abstract—We consider the convergence issues of distributed powercontrol algorithms for mobile cellular systems. A convergence theorem for powercontrol algorithms of canonical type is proved. Our result generalizes Yates ’ framework and provides a new outlook on the problem. The general applicabili ..."
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Cited by 22 (2 self)
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Abstract—We consider the convergence issues of distributed powercontrol algorithms for mobile cellular systems. A convergence theorem for powercontrol algorithms of canonical type is proved. Our result generalizes Yates ’ framework and provides a new outlook on the problem. The general applicability of the theorem is demonstrated by showing that many wellknown distributed algorithms are canonical. Furthermore, by devising some new discrete algorithms, we exemplify how the theorem can be used to aid new design. Index Terms—Canonical algorithm, distributed algorithms, framework, power control. I.
Distributed InterferenceAware EnergyEfficient Power Optimization
"... Abstract—Power optimization techniques are becoming increasingly important in wireless system design since battery technology has not kept up with the demand of mobile devices. They are also critical to interference management in wireless systems because interference usually results from both aggr ..."
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Cited by 19 (1 self)
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Abstract—Power optimization techniques are becoming increasingly important in wireless system design since battery technology has not kept up with the demand of mobile devices. They are also critical to interference management in wireless systems because interference usually results from both aggressive spectral reuse and high power transmission and severely limits system performance. In this paper, we develop an energyefficient power optimization scheme for interferencelimited wireless communications. We consider both circuit and transmission powers and focus on energy efficiency over throughput. We first investigate a noncooperative game for energyefficient power optimization in frequencyselective channels and reveal the conditions of the existence and uniqueness of the equilibrium for this game. Most importantly, we discover a sufficient condition for generic multichannel power control to have a unique equilibrium in frequencyselective channels. Then we study the tradeoff between energy efficiency and spectral efficiency and show by simulation results that the proposed scheme improves both energy efficiency and spectral efficiency in an interferencelimited multicell cellular network. Index Terms—Interference, energy efficiency, power optimization, OFDM, noncooperative power control. I.
A repeated game formulation of energyefficient decentralized power control
 IEEE TRANS. ON WIRELESS COMMUNICATIONS
, 2010
"... Decentralized multiple access channels where each transmitter wants to selfishly maximize his transmission energyefficiency are considered. Transmitters are assumed to choose freely their power control policy and interact (through multiuser interference) several times. It is shown that the correspo ..."
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Cited by 18 (7 self)
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Decentralized multiple access channels where each transmitter wants to selfishly maximize his transmission energyefficiency are considered. Transmitters are assumed to choose freely their power control policy and interact (through multiuser interference) several times. It is shown that the corresponding conflict of interest can have a predictable outcome, namely a finitely or discounted repeated game equilibrium. Remarkably, it is shown that this equilibrium is Paretoefficient under reasonable sufficient conditions and the corresponding decentralized power control policies can be implemented under realistic information assumptions: only individual channel state information and a public signal are required to implement the equilibrium strategies. Explicit equilibrium conditions are derived in terms of minimum number of game stages or maximum discount factor. Both analytical and simulation results are provided to compare the performance of the proposed power control policies with those already existing and exploiting the same information assumptions namely, those derived for the oneshot and Stackelberg games.
Utilitybased powercontrol for a twocell CDMA data network
 IEEE Trans. Wireless Commun
, 2005
"... Abstract—Power allocation across users in two adjacent cells is studied for a codedivision multiple access (CDMA) data service. The forward link is considered and cells are modeled as onedimensional with uniformly distributed users and orthogonal signatures within each cell. Each user is assumed t ..."
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Cited by 17 (3 self)
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Abstract—Power allocation across users in two adjacent cells is studied for a codedivision multiple access (CDMA) data service. The forward link is considered and cells are modeled as onedimensional with uniformly distributed users and orthogonal signatures within each cell. Each user is assumed to have a utility function that describes the user’s received utility, or willingness to pay, for a received signaltointerferenceplusnoise ratio (SINR). The objective is to allocate the transmitted power to maximize the total utility summed over all users subject to power constraints in each cell. It is first shown that this optimization can be achieved by a pricing scheme in which each base station announces a price per unit transmitted power to the users, and each user requests power to maximize individual surplus (utility minus cost). Setting prices to maximize total revenue over both cells is also considered, and it is shown that, in general, the solution is different from the one obtained by maximizing total utility. Conditions are given for which independent optimization in each cell, which leads to a Nash equilibrium (NE), is globally optimal. It is shown that, in general, coordination between the two cells is needed to achieve the maximum utility or revenue. Index Terms—CDMA, data service, forward link, power control, pricing, resource allocation, revenue, surplus, utility. I.