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113
Efficient Communication Strategies for AdHoc Wireless Networks
, 2000
"... An adhoc wireless network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. This type of network is of great importance in situations where it is very difficult to provide the necessary infrastructur ..."
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Cited by 37 (3 self)
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An adhoc wireless network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration. This type of network is of great importance in situations where it is very difficult to provide the necessary infrastructure, but it is a challenging task to enable fast and reliable communication within such a network. In this paper, we model and analyze the performance of socalled powercontrolled adhoc wireless networks: networks where the mobile hosts are able to change their transmission power. We concentrate on finding schemes for routing arbitrary permutations in these networks. In general, it is NPhard even to find a n 1 approximation for any constant to the fastest possible strategy for routing a given permutation problem on n mobile hosts. However, we here demonstrate that if we allow ourselves to consider slightly less general problems, efficient solutions can be found. We first demonstrate that there is a natural class of distributed schemes for handling nodetonode communication on top of which online route selection and scheduling strategies can be constructed such that the performance of this class of schemes can be exploited in a nearly optimal way for routing permutations in any static powercontrolled adhoc network. We then demonstrate
A Power Control Game Based on Outage Probabilities for Multicell Wireless Data Networks
 in Proc. of American Control Conference (ACC) 2004
, 2004
"... We present a gametheoretic treatment of distributed power control in CDMA wireless systems using outage probabilities. We prove that the noncooperative power control game considered admits a unique Nash equilibrium (NE) for uniformly strictly convex pricing functions and under some technical assump ..."
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Cited by 33 (11 self)
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We present a gametheoretic treatment of distributed power control in CDMA wireless systems using outage probabilities. We prove that the noncooperative power control game considered admits a unique Nash equilibrium (NE) for uniformly strictly convex pricing functions and under some technical assumptions on the SIR threshold levels. We analyze global convergence of continuoustime as well as discretetime synchronous and asynchronous iterative power update algorithms to the unique NE of the game. Furthermore, a stochastic version of the discretetime update scheme, which models the uncertainty due to quantization and estimation errors, is shown to converge almost surely to the unique NE point. We further investigate and demonstrate the convergence and robustness properties of these update schemes through simulation studies.
The minimum range assignment problem on linear radio networks
, 2000
"... Given a set of radio stations located on a line and an integer, the MIN ASSIGNMENT problem consists in finding a range assignment of minimum power consumption provided that any pair of stations can communicate in at most hops. Previous positive results for this problem are only known when or in the ..."
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Cited by 29 (7 self)
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Given a set of radio stations located on a line and an integer, the MIN ASSIGNMENT problem consists in finding a range assignment of minimum power consumption provided that any pair of stations can communicate in at most hops. Previous positive results for this problem are only known when or in the uniform chain case (i.e. when the stations are equally spaced). As for the first case, Kirousis, Kranakis, Krizanc and Pelc (1997) provided a polynomialtime algorithm while, for the second case, they derive a polynomialtime approximation algorithm. This paper presents the first polynomialtime, approximation algorithm for the MIN ASSIGNMENT problem. The algorithm guarantees a 2 approximation ratio and runs in time. We also prove that, for fixed and for “well spaced ” instances (a broad generalization of the uniform chain case), the problem admits a polynomialtime approximation scheme (PTAS). This result significantly improves over the approximability result given by Kirousis et al. Both our approximation results are obtained via new algorithms that exactly solve two natural variants of the MIN ASSIGNMENT problem: the problem in which every station must reach a fixed one in at most hops and the problem in which the goal is to select a subset of bases such that all the other stations must
Stochastic learning solution for distributed discrete power control game in wireless data networks
, 2008
"... Distributed power control is an important issue in wireless networks. Recently, noncooperative game theory has been applied to investigate interesting solutions to this problem. The majority of these studies assumes that the transmitter power level can take values in a continuous domain. However, r ..."
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Cited by 27 (0 self)
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Distributed power control is an important issue in wireless networks. Recently, noncooperative game theory has been applied to investigate interesting solutions to this problem. The majority of these studies assumes that the transmitter power level can take values in a continuous domain. However, recent trends such as the GSM standard and Qualcomm’s proposal to the IS95 standard use a finite number of discretized power levels. This motivates the need to investigate solutions for distributed discrete power control which is the primary objective of this paper. We first note that, by simply discretizing, the previously proposed continuous power adaptation techniques will not suffice. This is because a simple discretization does not guarantee convergence and uniqueness. We propose two probabilistic power adaptation algorithms and analyze their theoretical properties along with the numerical behavior. The distributed discrete power control problem is formulated as anperson, nonzero sum game. In this game, each user evaluates a power strategy by computing a utility value. This evaluation is performed using a stochastic iterative procedures. We approximate the discrete power control iterations by an equivalent ordinary differential equation to prove that the proposed stochastic learning power control algorithm converges to a stable Nash equilibrium. Conditions when more than one stable Nash equilibrium or even only mixed equilibrium may exist are also studied. Experimental results are presented for several cases and compared with the continuous power level adaptation solutions.
Models and Techniques for Communication in Dynamic Networks Christian
 In Proc. of the 19th Symp. on Theoretical Aspects of Computer Science (STACS
, 2001
"... In this paper we will present various models and techniques for communication in dynamic networks. Dynamic networks are networks of dynamically changing bandwidth or topology. Situations in which dynamic networks occur are, for example: faulty networks (links go up and down), the Internet (the bandw ..."
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Cited by 26 (2 self)
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In this paper we will present various models and techniques for communication in dynamic networks. Dynamic networks are networks of dynamically changing bandwidth or topology. Situations in which dynamic networks occur are, for example: faulty networks (links go up and down), the Internet (the bandwidth of connections may vary), and wireless networks (mobile units move around). We investigate the problem of how to ensure connectivity, how to route, and how to perform admission control in these networks. Some of these problems have already been partly solved, but many problems are still wide open. The aim of this paper is to give an overview of recent results in this area, to identify some of the most interesting open problems and to suggest models and techniques that allow us to study them.
Distributed power control for time varying wireless networks: Optimality and convergence
 in Proceedings: Allerton Conference on Communications, Control, and Computing
, 2003
"... This paper presents a new distributed power control algorithm for adhoc wireless networks in random channel environments. Previous work in this area has focused on distributed power control for adhoc networks with fixed channels. We show that the algorithms resulting from such formulations do not ..."
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Cited by 22 (1 self)
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This paper presents a new distributed power control algorithm for adhoc wireless networks in random channel environments. Previous work in this area has focused on distributed power control for adhoc networks with fixed channels. We show that the algorithms resulting from such formulations do not accurately capture the dynamics of a timevarying channel. The performance of the network, in terms of power consumption and generated interference, can be severely degraded when a power control algorithm designed for a deterministic channel is applied to a random channel. In particular, some wellknown strong optimality results for such algorithms no longer hold. In order to address these problems we propose a new criterion for power optimality in adhoc wireless networks. We then show that the optimal power allocation for this new criterion can be found through an appropriate stochastic approximation algorithm. Ultimately, the iterations of the stochastic approximation algorithm can be decoupled to form an optimal fully distributed online power control algorithm for adhoc wireless networks with timevarying channels. 1
Design and Performance Analysis of Wireless Network
, 2000
"... In this thesis we are concerned with the problems of data transport in wireless networks. We study some issues related to the design and performance evaluation of multihop wireless networks, also known as ad hoc networks. The rst issue that we address is the power requirement for assuring connectivi ..."
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Cited by 22 (3 self)
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In this thesis we are concerned with the problems of data transport in wireless networks. We study some issues related to the design and performance evaluation of multihop wireless networks, also known as ad hoc networks. The rst issue that we address is the power requirement for assuring connectivity of wireless networks. Employing some results from continuum percolation theory, we obtain a precise characterization of the critical transmission range of nodes in a wireless network such that the network is connected with probability approaching one as the number of nodes increases. We next analyze the traÆccarrying capacity of multihop wireless networks. We show that under some noninterference models motivated by current technology, the average throughput obtained by nodes in a twodimensional wireless network decreases as the reciprocal of the square root of the number of nodes in the network. We also show that a similar cube root law holds for threedimensional wireless networks. In doing so, we determine the VapnikChervonenkis dimensions of certain geometric sets, which may be of independent interest. We also study wireless networks in a more informationtheoretic framework, which allows
Control of Mobile Communications with Time Varying Channels in Heavy Traffic
 IEEE Trans. Automat. Control
, 2001
"... Consider a system with a xed number (K) of remote units and a single base transmitter with time varying (and perhaps correlated) connecting channels. Data to be transmitted to the remote units arrives according to some random process and is queued according to its destination. The forward link is tr ..."
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Cited by 22 (4 self)
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Consider a system with a xed number (K) of remote units and a single base transmitter with time varying (and perhaps correlated) connecting channels. Data to be transmitted to the remote units arrives according to some random process and is queued according to its destination. The forward link is treated. Power is to be allocated to the K channels in a queue and channel state dependent way to minimize some cost criterion. The modeling and control problem can be quite difficult. The channel time variations (fading) are fast and the bandwidth and data arrival rates are high. Owing to the complexity of the physical problem and the high speed of both the fading and arrival and service rates, an asymptotic or averaging method is promising. A heavy traffic analysis is done. By heavy traffic, we mean that on the average there is little server idle time and little spare power over the "average" requirements. Heavy traffic analysis has been very helpful in simplifying analysis of both controlled and uncontrolled problems in queueing and communications networks. It tends to eliminate unessential detail and focus on the fundamental issues of scaling and parametric dependencies. To illustrate the scope of the method, a variety of models are considered. The basic model assumes that the channel state is known or can be well estimated and that given the channel state there is a well defined rate of transmission per unit power. Then convergence of the controlled scaled queue lengths is shown. The scaling is different from the usual in heavy traffic work, and the limit Wiener process depends only on the channel state process and not on the...
Controlling QoS by Integrated Power Control and Link Adaptation in Broadband Wireless Networks
, 1999
"... . We propose and analyze the performance of an algorithm for integrated power control and adaptive modulation/coding to achieve a specified range of packet error rate for realtime applications in broadband wireless packetswitched networks. The algorithm applies the Kalmanfilter method [1] for p ..."
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Cited by 20 (5 self)
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. We propose and analyze the performance of an algorithm for integrated power control and adaptive modulation/coding to achieve a specified range of packet error rate for realtime applications in broadband wireless packetswitched networks. The algorithm applies the Kalmanfilter method [1] for power control, and adapts packet transmission to an appropriate modulation level, according to the packet error requirement, and the radio and interference conditions. A new criterion for maintaining stable transmission power is derived. Based on the criterion, the proposed technique performs the link adaptation and adjusts transmission power to achieve the specified packet error rate. The effectiveness of the proposed method is demonstrated by several numerical examples. 1 INTRODUCTION Customers' demand for broadband network services has been growing significantly as telecommuting and Internet access become increasingly popular. In the very near future, broadband services are also exp...