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MultiCell MIMO Cooperative Networks: A New Look at Interference
 J. Selec. Areas in Commun. (JSAC
, 2010
"... Abstract—This paper presents an overview of the theory and currently known techniques for multicell MIMO (multiple input multiple output) cooperation in wireless networks. In dense networks where interference emerges as the key capacitylimiting factor, multicell cooperation can dramatically improv ..."
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Abstract—This paper presents an overview of the theory and currently known techniques for multicell MIMO (multiple input multiple output) cooperation in wireless networks. In dense networks where interference emerges as the key capacitylimiting factor, multicell cooperation can dramatically improve the system performance. Remarkably, such techniques literally exploit intercell interference by allowing the user data to be jointly processed by several interfering base stations, thus mimicking the benefits of a large virtual MIMO array. Multicell MIMO cooperation concepts are examined from different perspectives, including an examination of the fundamental informationtheoretic limits, a review of the coding and signal processing algorithmic developments, and, going beyond that, consideration of very practical issues related to scalability and systemlevel integration. A few promising and quite fundamental research avenues are also suggested. Index Terms—Cooperation, MIMO, cellular networks, relays, interference, beamforming, coordination, multicell, distributed.
Downlink Channel Assignment and Power Control for Cognitive Radio Networks
, 2008
"... We consider a cognitive radio network in which a set of base stations make opportunistic spectrum access to support fixedlocation wireless subscribers within their cells. The spectrum of interest is divided into independent channels using frequency division multiple access (FDMA) and is licensed t ..."
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Cited by 14 (0 self)
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We consider a cognitive radio network in which a set of base stations make opportunistic spectrum access to support fixedlocation wireless subscribers within their cells. The spectrum of interest is divided into independent channels using frequency division multiple access (FDMA) and is licensed to the operator of a primary network. Channel assignment and power control must be carried out in the cognitive network so that no excessive interference is caused to users of the primary network. We are interested in the downlink channel/power allocation problem for the cognitive radio network, with the objective of maximizing the total number of active subscribers that can be supported. Here, we assume that each subscriber of the cognitive network can be either active or idle and only active subscribers require downlink transmission. We first consider the case when global knowledge of all active subscribers is available for making control decisions. In that case, a downlink channel/power allocation scheme that maximizes the number of supported subscribers can be obtained by solving a mixedinteger linear programming. We also propose a suboptimal scheme that can be obtained at lower complexity based on a dynamic interference graph. We then consider the case when control decisions can only be made based on local knowledge of active subscribers within each cell. For that, we propose a scalable twophase channel/power allocation scheme. Numerical results show the effectiveness of our proposed schemes.
Asymptotic optimality for distributed spectrum sharing using bargaining solutions
 IEEE Trans. Wireless Commun
, 2009
"... Abstract—Recent studies on spectrum usage reveal poor utilization, both spatially and temporally. Opportunistic use of licensed spectrum while limiting interference to primary users can enhance spectrum reuse and provide orders of magnitude improvement in available channel capacity. This calls for ..."
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Cited by 12 (2 self)
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Abstract—Recent studies on spectrum usage reveal poor utilization, both spatially and temporally. Opportunistic use of licensed spectrum while limiting interference to primary users can enhance spectrum reuse and provide orders of magnitude improvement in available channel capacity. This calls for spectrum sharing protocols that are dynamic, exible, and efcient, in addition to being fair to end users. We employ cooperative game theory to address the opportunistic spectrum access problem. Specically, we develop a gametheoretic model to analyze a scenario in which nodes in a wireless network seek to agree on a fair and efcient allocation of spectrum. First, we show that in high interference environments, the utility space of the game is nonconvex, making certain optimal allocations unachievable with pure strategies. To mitigate this, we show that as the number of channels available increases, the utility space approaches convexity, thereby making optimal allocations achievable with pure strategies. Second, by comparing and analyzing three bargaining solutions, we show that the Nash Bargaining Solution achieves the best tradeoff between fairness and efciency, using a small number of channels. Finally, we develop a distributed algorithm for spectrum sharing that is general enough to accomodate nonzero disagreement points, and show that it achieves allocations reasonably close to the Nash Bargaining Solution. Index Terms—Dynamic spectrum access, cooperation, game theory, radio resource management, Nash bargaining solution. I.
Economic Approaches for Cognitive Radio Networks: A Survey
"... Abstract Efficient resource allocation is one of the key concerns of implementing cognitive radio networks. Game theory has been extensively used to study the strategic interactions between primary and secondary users for effective resource allocation. The concept of spectrum trading has introduced ..."
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Abstract Efficient resource allocation is one of the key concerns of implementing cognitive radio networks. Game theory has been extensively used to study the strategic interactions between primary and secondary users for effective resource allocation. The concept of spectrum trading has introduced a new direction for the coexistence of primary and secondary users through economic benefits to primary users. The use of price theory and market theory from economics has played a vital role to facilitate economic models for spectrum trading. So, it is important to understand the feasibility of using economic approaches as well as to realize the technical challenges associated with them for implementation of cognitive radio networks. With this motivation, we present an extensive summary of the related work that use economic approaches such as game theory and/or price theory/market theory to model the behavior of primary and secondary users for spectrum sharing and discuss the associated issues. We also propose some open directions for future research on economic aspects of spectrum sharing in cognitive radio networks.
QueueAware Distributive Resource Control for DelaySensitive TwoHop
 MIMO Cooperative Systems”, IEEE Trans. Signal Proc
, 2011
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1Energyefficient Resource Allocation for Uplink OFDMA Systems Using Correlated Equilibrium
"... Abstract—In this work, we propose a correlated equilibrium (CE)based energyefficient resource allocation scheme for uplink OFDMA systems. At first, we construct an energyefficient resource allocation game, where each subcarrier is viewed as a player to choose the most satisfying user, and the obj ..."
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Abstract—In this work, we propose a correlated equilibrium (CE)based energyefficient resource allocation scheme for uplink OFDMA systems. At first, we construct an energyefficient resource allocation game, where each subcarrier is viewed as a player to choose the most satisfying user, and the objective is to balance the tradeoff between the total energy efficiency and the fairness. Since the CE can achieve better performance by helping the noncooperative players coordinate their strategies, we employ the CE to analyze the proposed game. Next, we derive the condition under which the CE is Pareto optimal and employ linear programming duality to show its closedform expressions. Furthermore, we present a linear programming method and a distributed algorithm based on the regret matching procedure to implement the CE, respectively. Simulation results demonstrate that our scheme is able to achieve good convergence, Pareto optimality, and fairness. Index Terms—OFDMA, correlated equilibrium, regret matching, linear programming, energy efficiency, resource allocation. I.
Downlink Channel Assignment and Power Control for Cognitive Radio Networks Using Game Theory
"... Abstract—We consider a cognitive radio network in which a set of base stations make opportunistic spectrum access to support cognitive radios within their cells. As the spectrum of interest is licensed to the operator of a primary network, channel assignment and power control must be carried out in ..."
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Abstract—We consider a cognitive radio network in which a set of base stations make opportunistic spectrum access to support cognitive radios within their cells. As the spectrum of interest is licensed to the operator of a primary network, channel assignment and power control must be carried out in the cognitive network so that no excessive interference is caused to users of the primary network. Given this constraint, we are interested in the downlink channel/power allocation problem, with the objective of maximizing the total number of supported CRs. Since the problem belongs to the class of NPhard problems, it is desirable to model and analyze it using game theory. First, we formulate the problem as a noncooperative game. For distributed power allocation, we use Iterative Water Filling algorithm. Numerical results show that the pure noncooperative game may result in nonconvergence or many undesirable Nash equilibria with few supported CRs. To enhance the performances Nash bargaining solution (NBS) is used. NBS requires the cooperation between BSs but still power allocation is done in a distributed manner using ITW. Index Terms—Cognitive radio network, iterative water filling, noncooperative game, cooperative game and Nash bargaining solution. I.
Contents lists available at ScienceDirect Chemical Physics Letters
"... journal homepage: www.elsevier.com/locate/cplett Firstprinciples study of the B or Ndoping effects on chemical bonding ..."
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journal homepage: www.elsevier.com/locate/cplett Firstprinciples study of the B or Ndoping effects on chemical bonding
Contents 1 Spectrum Sharing Games of Network Operators and Cognitive Radios
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1ClosedForm DelayOptimal Power Control for Energy Harvesting Wireless System with Finite Energy Storage
"... Abstract—In this paper, we consider delayoptimal power control for an energy harvesting wireless system with finite energy storage. The wireless system is powered solely by a renewable energy source with bursty data arrivals, and is characterized by a data queue and an energy queue. We consider a d ..."
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Abstract—In this paper, we consider delayoptimal power control for an energy harvesting wireless system with finite energy storage. The wireless system is powered solely by a renewable energy source with bursty data arrivals, and is characterized by a data queue and an energy queue. We consider a delayoptimal power control problem and formulate an infinite horizon average cost Markov Decision Process (MDP). To deal with the curse of dimensionality, we introduce a virtual continuous time system and derive closedform approximate priority functions for the discrete time MDP at various operating regimes. Based on the approximation, we obtain an online power control solution which is adaptive to the channel state information as well as the data and energy queue state information. The derived power control solution has a multilevel waterfilling structure, where the water level is determined jointly by the data and energy queue lengths. We show through simulations that the proposed scheme has significant performance gain compared with various baselines. I.