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38
Spectrum Sharing for Unlicensed Bands
 in IEEE DySPAN 2005
, 2005
"... We study a spectrum sharing problem in an unlicensed band where multiple systems coexist and interfere with each other. Due to asymmetries and selfish system behavior, unfair and inefficient situations may arise. We investigate whether efficiency and fairness can be obtained with selfenforcing spe ..."
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Cited by 157 (3 self)
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We study a spectrum sharing problem in an unlicensed band where multiple systems coexist and interfere with each other. Due to asymmetries and selfish system behavior, unfair and inefficient situations may arise. We investigate whether efficiency and fairness can be obtained with selfenforcing spectrum sharing rules. These rules have the advantage of not requiring a central authority that verifies compliance to the protocol. Any selfenforcing protocol must correspond to an equilibrium of a game. We first analyze the possible outcomes of a one shot game, and observe that in many cases an inefficient solution results. However, systems often coexist for long periods and a repeated game is more appropriate to model their interaction. In this repeated game the possibility of building reputations and applying punishments allows for a larger set of selfenforcing outcomes. When this set includes the optimal operating point, efficient, fair, and incentive compatible spectrum sharing becomes possible. We present examples that illustrate that in many cases the performance loss due to selfish behavior is small. We also prove that our results are tight and quantify the best achievable performance in a noncooperative scenario.
An introduction to convex optimization for communications and signal processing
 IEEE J. Sel. Areas Commun
, 2006
"... Abstract—Convex optimization methods are widely used in the ..."
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Cited by 29 (2 self)
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Abstract—Convex optimization methods are widely used in the
Maximizing Capacity in Arbitrary Wireless Networks in the SINR Model: Complexity and Game Theory
"... Abstract—In this paper we consider the problem of maximizing the number of supported connections in arbitrary wireless networks where a transmission is supported if and only if the signaltointerferenceplusnoise ratio at the receiver is greater than some threshold. The aim is to choose transmissi ..."
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Cited by 27 (2 self)
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Abstract—In this paper we consider the problem of maximizing the number of supported connections in arbitrary wireless networks where a transmission is supported if and only if the signaltointerferenceplusnoise ratio at the receiver is greater than some threshold. The aim is to choose transmission powers for each connection so as to maximize the number of connections for which this threshold is met. We believe that analyzing this problem is important both in its own right and also because it arises as a subproblem in many other areas of wireless networking. We study both the complexity of the problem and also present some game theoretic results regarding capacity that is achieved by completely distributed algorithms. We also feel that this problem is intriguing since it involves both continuous aspects (i.e. choosing the transmission powers) as well as discrete aspects (i.e. which connections should be supported).
Energyefficient resource allocation in wireless networks: An overview of gametheoretic approaches
 IEEE Signal Process. Magazine
, 2007
"... A gametheoretic model is proposed to study the crosslayer problem of joint power and rate control with quality of service (QoS) constraints in multipleaccess networks. In the proposed game, each user seeks to choose its transmit power and rate in a distributed manner in order to maximize its own ..."
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Cited by 22 (6 self)
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A gametheoretic model is proposed to study the crosslayer problem of joint power and rate control with quality of service (QoS) constraints in multipleaccess networks. In the proposed game, each user seeks to choose its transmit power and rate in a distributed manner in order to maximize its own utility while satisfying its QoS requirements. The user’s QoS constraints are specified in terms of the average source rate and an upper bound on the average delay where the delay includes both transmission and queuing delays. The utility function considered here measures energy efficiency and is particularly suitable for wireless networks with energy constraints. The Nash equilibrium solution for the proposed noncooperative game is derived and a closedform expression for the utility achieved at equilibrium is obtained. It is shown that the QoS requirements of a user translate into a “size ” for the user which is an indication of the amount of network resources consumed by the user. Using this competitive multiuser framework, the tradeoffs among throughput, delay, network capacity and energy efficiency are studied. In addition, analytical expressions are given for users ’ delay profiles and the delay performance of the users at Nash equilibrium is quantified.
A new decentralized power allocation strategy in singlehop wireless networks
 HOPKINS UNIVERSITY
, 2006
"... In this paper, a simple decentralized power allocation strategy is proposed, which relies on the local information in a singlehop wireless network with n links. The main goal of the strategy is to improve the average sumrate. We first define a new utilitybased framework, in which each user takes ..."
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Cited by 5 (4 self)
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In this paper, a simple decentralized power allocation strategy is proposed, which relies on the local information in a singlehop wireless network with n links. The main goal of the strategy is to improve the average sumrate. We first define a new utilitybased framework, in which each user takes into account the negative impact of its power increment on the other users performance. For large n and by knowing only the direct channel gain hii, the optimum strategy for user i is to transmit with full power or remain silent. The transmission policy is to compare hii with a prespecified threshold τn that is a function of n. Under a Rayleigh fading channel condition, it is demonstrated that among n pairs of nodes, the average number of active links is of order log n. Also, the average sumrate scales as Θ(log n). The performance of the proposed strategy is compared with that of the centralized power allocation scheme and the noncooperative power control games through simulation and the analytical arguments. The proposed onoff power allocation scheme has the advantage of not requiring a central controller. The proposed strategy relies on a one shot game with a simple structure, rather than the iterative mechanism used in the pricing algorithm. These properties make our scheme more practical in timevarying networks.
Fast algorithms and performance bounds for sum rate maximization in wireless networks
 in Proceedings of IEEE INFOCOM
, 2009
"... Abstract — Sum rate maximization by power control is an important, challenging, and extensively studied problem in wireless networks. It is a nonconvex optimization problem and achieves a rate region that is in general nonconvex. We derive approximation ratios to the sum rate objective by studying t ..."
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Cited by 5 (2 self)
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Abstract — Sum rate maximization by power control is an important, challenging, and extensively studied problem in wireless networks. It is a nonconvex optimization problem and achieves a rate region that is in general nonconvex. We derive approximation ratios to the sum rate objective by studying the solutions to two related problems, sum rate maximization using an SIR approximation and maxmin weighted SIR optimization. We also show that these two problems can be solved very efficiently, using much faster algorithms than the existing ones in the literature. Furthermore, using a new parameterization of the sum rate maximization problem, we obtain a characterization of the power controlled rate region and its convexity property in various asymptotic regimes. Engineering implications are discussed for IEEE 802.11 networks. Index Terms — Duality, Distributed algorithm, Power control, Weighted sum rate maximization, Nonnegative matrices and applications,
Distributed power control for cognitive user access based on primary link control feedback
 In IEEE Infocom. IEEE
, 2010
"... Abstract—We venture beyond the “listenbeforetalk ” strategy that is common in many traditional cognitive radio access schemes. We exploit the bidirectional nature of most primary communication systems. By intelligently choosing their transmission parameters based on the observation of primary use ..."
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Cited by 3 (2 self)
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Abstract—We venture beyond the “listenbeforetalk ” strategy that is common in many traditional cognitive radio access schemes. We exploit the bidirectional nature of most primary communication systems. By intelligently choosing their transmission parameters based on the observation of primary user (PU) communications, secondary users (SUs) in a cognitive network can achieve higher spectrum usage while limiting their interference to the PU. Specifically, we propose that the SUs listen to the PU’s feedback channel to assess their interference on the primary receiver (PURx), and adjust radio power accordingly to satisfy the PU’s interference constraint. We investigate both centralized and distributed power control algorithms without active PU cooperation. We show that the PU feedback information inherent in many twoway primary systems can be used as important coordination signal among multiple SUs to distributively achieve a joint performance guarantee on the primary receiver’s quality of service. data link control information is available in many practical systems, e.g., power control feedback in CDMA cellular systems [6], channel quality indicator (CQI) feedback in HSDPA [6], and ACK/NACK feedback in cellular and WiFi networks [6], [7]. Such feedback information from the PU receiver can serve as a good indicator of the actual (often aggregated) impact of the SU interference on the reception quality of the PU communication link. SURx PUTx
A NonCooperative Power Control Game for Secondary Spectrum Sharing
"... Abstract—Limited spectrum resources, inefficient spectrum usage and increasing wireless communication necessitates a paradigm shift from the current fixed spectrum management policy to a more flexible one. With the Federal Communications Commission’s (FCC) spectrum policy reform, secondary spectrum ..."
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Cited by 2 (0 self)
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Abstract—Limited spectrum resources, inefficient spectrum usage and increasing wireless communication necessitates a paradigm shift from the current fixed spectrum management policy to a more flexible one. With the Federal Communications Commission’s (FCC) spectrum policy reform, secondary spectrum sharing has become a viable and promising option. In this paper, we study power control for spectrum sharing among secondary users with interference temperature limit (ITL) constraints at measurement points. Each secondary user will adjust its own transmission power to make sure the overall interference at the measurement points does not exceed the required ITL. Under the assumption that each secondary user is selfish and rational while there is only limited coordination between primary users and secondary users, we study the distributed power control scheme for secondary users. In our proposed system model, secondary users generating the highest interference at a measurement point will back off their transmissions if the ITL is exceeded. A noncooperative power control game among secondary users is proposed to maximize each user’s utility. We identify the Nash equilibrium of the proposed game and analyze its property. Simulations are conducted to demonstrate that the proposed solution can achieve a satisfactory performance in terms of the total transmitting rate of all the secondary users. I.
Maximizing Sum Rates in Gaussian Interferencelimited Channels
, 2008
"... We study the problem of maximizing sum rates in Gaussian interferencelimited channels. We show that this maximum problem can be restated as a maximization problem of a convex function on a closed convex set. We suggest three algorithms to find the exact and approximate values of the optimal rates. ..."
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Cited by 2 (2 self)
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We study the problem of maximizing sum rates in Gaussian interferencelimited channels. We show that this maximum problem can be restated as a maximization problem of a convex function on a closed convex set. We suggest three algorithms to find the exact and approximate values of the optimal rates.
EnergyRobustness Tradeoff in Cellular Network Power Control
"... Abstract — In the seminal paper by Foschini and Miljanic in 1993, a distributed power control algorithm was developed to meet SIR targets with minimal powers in cellular network uplinks. Since the SIR on an active link may dip below the SIR target during the transient after a new user enters the cel ..."
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Cited by 1 (0 self)
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Abstract — In the seminal paper by Foschini and Miljanic in 1993, a distributed power control algorithm was developed to meet SIR targets with minimal powers in cellular network uplinks. Since the SIR on an active link may dip below the SIR target during the transient after a new user enters the cell, Bambos et al. proposed an active link protection algorithm to provide robustness, at the expense of higher energy consumption. This paper examines the tradeoff between energy and robustness. An optimization problem is formulated where robustness is captured in the constraint and the price of robustness penalized in the objective function. A distributed algorithm is developed to solve this problem. Local convergence and optimality of equilibrium are proved for the algorithm. The objective function modulates the tradeoff between energy and robustness, and between energy and speed of admission, as illustrated through a series of numerical experiments. A parameterized family of objective functions is constructed to control the transient and equilibrium properties of robust distributed power control.