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26
Planning UMTS Base Station Location: Optimization Models with Power Control and Algorithms
 IEEE Transactions on Wireless Communications
, 2003
"... Classical coverage models, adopted for secondgeneration cellular systems, are not suited for planning universal mobile telecommunication system (UMTS) base station (BS) location because they are only based on signal predictions and do not consider the traffic distribution, the signal quality requir ..."
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Cited by 64 (11 self)
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Classical coverage models, adopted for secondgeneration cellular systems, are not suited for planning universal mobile telecommunication system (UMTS) base station (BS) location because they are only based on signal predictions and do not consider the traffic distribution, the signal quality requirements, and the power control (PC) mechanism. In this paper, we propose discrete optimization models and algorithms aimed at supporting the decisions in the process of planning where to locate new BSs. These models consider the signaltointerference ratio as quality measure and capture at different levels of detail the signal quality requirements and the specific PC mechanism of the wideband CDMA air interface. Given that these UMTS BS location models are nonpolynomial (NP)hard, we propose two randomized greedy procedures and a tabu search algorithm for the uplink (mobile to BS) direction which is the most stringent one from the traffic point of view in the presence of balanced connections such as voice calls. The different models, which take into account installation costs, signal quality and traffic coverage, and the corresponding algorithms, are compared on families of small to largesize instances generated by using classical propagation models.
ConflictFree Colorings of Simple Geometric Regions with Applications to Frequency Assignment in Cellular Networks
, 2002
"... Motivated by a frequency assignment problem in cellular networks, we introduce and study a new coloring problem that we call Minimum ConflictFree Coloring (MinCFColoring). In its general form, the input of the MinCFcoloring problem is a set system (X, S), where each S 2 S is a subset of X . The ..."
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Cited by 60 (8 self)
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Motivated by a frequency assignment problem in cellular networks, we introduce and study a new coloring problem that we call Minimum ConflictFree Coloring (MinCFColoring). In its general form, the input of the MinCFcoloring problem is a set system (X, S), where each S 2 S is a subset of X . The output is a coloring of the sets in S that satisfies the following constraint: for every x 2 X there exists a color i and a unique set S 2 S, such that x 2 S and (S) = i. The goal is to minimize the number of colors used by the coloring .
Poweraware Base Station Positioning for Sensor Networks
 in Proc. IEEE Infocom
, 2004
"... We consider the problem of positioning data collecting base stations in a sensor network. We show that in general, the choice of positions has a marked influence on the data rate, or equivalently, the power efficiency, of the network. In our model, which is partly motivated by an experimental enviro ..."
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Cited by 40 (0 self)
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We consider the problem of positioning data collecting base stations in a sensor network. We show that in general, the choice of positions has a marked influence on the data rate, or equivalently, the power efficiency, of the network. In our model, which is partly motivated by an experimental environmental monitoring system, the optimum data rate for a fixed layout of base stations can be found by a maximum flow algorithm. Finding the optimum layout of base stations, however, turns out to be an NPcomplete problem, even in the special case of homogeneous networks. Our analysis of the optimum layout for the special case of the regular grid shows that all layouts that meet certain constraints are equally good. We also consider two classes of random graphs, chosen to model networks that might be realistically encountered, and empirically evaluate the performance of several base station positioning algorithms on instances of these classes. In comparison to manually choosing positions along the periphery of the network or randomly choosing them within the network, the algorithms tested find positions which significantly improve the data rate and power efficiency of the network.
Feasible Network Configurations for UMTS
, 2002
"... A model for the optimisation of the location and configuration of base stations in a UMTS network is described. The focus is primarily on modelling the configuration problem sufficiently accurate using mixedinteger variables and (essentially) linear constraints. These constraints reflect the limite ..."
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Cited by 22 (7 self)
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A model for the optimisation of the location and configuration of base stations in a UMTS network is described. The focus is primarily on modelling the configuration problem sufficiently accurate using mixedinteger variables and (essentially) linear constraints. These constraints reflect the limited downlink code capacity in each cell, the interference limitations for successful up and downlink transmissions, the need for sufficiently strong (cell) pilot signals, and the potential gain for mobiles from being in soft(er) handover. It is also explained how to use the model as a basis for rating network configurations.
Evolutionary multiobjective optimization for base station transmitter placement with frequency assignment
 IEEE Transactions on Evolutionary Computation
, 2003
"... We propose a new solution to the problem of positioning base station transmitters of a mobile phone network and assigning frequencies to the transmitters, both in an optimal way. Since an exact solution cannot be expected to run in polynomial time for all interesting versions of this problem (they a ..."
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Cited by 21 (0 self)
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We propose a new solution to the problem of positioning base station transmitters of a mobile phone network and assigning frequencies to the transmitters, both in an optimal way. Since an exact solution cannot be expected to run in polynomial time for all interesting versions of this problem (they are all NPhard), our algorithm follows a heuristic approach based on the evolutionary paradigm. For this evolution to be efficient, that is at the same time goaloriented and sufficiently random, problem specific knowledge is embedded in the operators. The problem requires both the minimization of the cost and of the channel interference. We examine and compare two standard multiobjective techniques and a new algorithm, the steady state evolutionary algorithm with Pareto tournaments (stEAPT). One major finding of the empirical investigation is a strong influence of the choice of the multiobjective selection method on the utility of the problemspecific recombination leading to a significant difference in the solution quality. I.
Station location  complexity and approximation
 IN PROCEEDINGS OF THE 5TH WORKSHOP ON ALGORITHMIC METHODS AND MODELS FOR OPTIMIZATION OF RAILWAYS (ATMOS ’05). IBFI DAGSTUHL
, 2005
"... We consider a geometric set covering problem. In its original form it consists of adding stations to an existing geometric transportation network so that each of a given set of settlements is not too far from a station. The problem is known to be NPhard in general. However, special cases with cert ..."
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Cited by 9 (0 self)
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We consider a geometric set covering problem. In its original form it consists of adding stations to an existing geometric transportation network so that each of a given set of settlements is not too far from a station. The problem is known to be NPhard in general. However, special cases with certain properties have been shown to be efficiently solvable in theory and in practice, especially if the covering matrix has (almost) consecutive ones property. In this paper we are narrowing the gap between intractable and efficiently solvable cases of the problem. We also present an approximation algorithm for cases with almost consecutive ones property.
Optimization problems and models for planning cellular networks
 Handbook of Optimization in Telecommunication, Eds. M. Resende and P. Pardalos
, 2006
"... Abstract: During the last decade the tremendous success of mobile phone systems has triggered considerable technological advances as well as the investigation of mathematical models and optimization algorithms to support planning and management decisions. In this chapter, we give an overview of some ..."
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Cited by 7 (2 self)
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Abstract: During the last decade the tremendous success of mobile phone systems has triggered considerable technological advances as well as the investigation of mathematical models and optimization algorithms to support planning and management decisions. In this chapter, we give an overview of some of the most significant optimization problems arising in planning second and third generation cellular networks, we describe the main corresponding mathematical models, and we briefly mention some of the computational approaches that have been devised to tackle them. For second generation systems (GSM), the planning problem can be subdivided into two distinct subproblems: coverage planning, in which the antennas are located so as to maximize service coverage, and capacity planning, in which frequencies are assigned to the antennas so as to maximize a measure of the overall quality of the received signals. For third generation systems (UMTS) network planning is even more challenging, since, due to the peculiarities of the radio interface, coverage and capacity issues must be simultaneously addressed.
Improving Customer Proximity to Railway Stations
 In Proc. CIAC 2003
, 2002
"... We consider problems of (nev) station placement along (existing) railvay tracks, so as to increase the number of users. We prove that, in spite of the NPhardness for the general version, some interesting cases can be solved exactly by a suitable dynamic programming approach. For variants in vhich ..."
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Cited by 5 (1 self)
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We consider problems of (nev) station placement along (existing) railvay tracks, so as to increase the number of users. We prove that, in spite of the NPhardness for the general version, some interesting cases can be solved exactly by a suitable dynamic programming approach. For variants in vhich ve also take into account existing connections betveen cities and railvay tracks (streets, buses, etc.) ve instead shov some hardness results.
Equivalence Problems for Boolean Constraint Satisfaction
, 2001
"... A Boolean constraint satisfaction instance is a conjunction of constraint applications, where the allowed constraints are drawn from a fi xed set C of Boolean functions. We consider the problem of determining whether two given constraint satisfaction instances are equivalent in the sense that they p ..."
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Cited by 5 (2 self)
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A Boolean constraint satisfaction instance is a conjunction of constraint applications, where the allowed constraints are drawn from a fi xed set C of Boolean functions. We consider the problem of determining whether two given constraint satisfaction instances are equivalent in the sense that they possess the same sets of satisfying assignments. We prove a Dichotomy Theorem by showing that for all sets C of allowed constraints, this problem is either polynomialtime solvable or coNPcomplete, and we give a simple criterion to determine which case holds. Another equivalence problem...