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17
Coordinated Target Assignment and Intercept for Unmanned Air Vehicles
, 2002
"... This paper presents an endtoend solution to the battlefield scenario where M unmanned air vehicles are assigned to strike N known targets, in the presence of dynamic threats. The problem is decomposed into the subproblems of (1) cooperative target assignment, (2) coordinated UAV intercept, (3) pat ..."
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Cited by 155 (16 self)
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This paper presents an endtoend solution to the battlefield scenario where M unmanned air vehicles are assigned to strike N known targets, in the presence of dynamic threats. The problem is decomposed into the subproblems of (1) cooperative target assignment, (2) coordinated UAV intercept, (3) path planning, and (4) feasible trajectory generation. The design technique is based on a hierarchical approach to coordinated control. Detailed simulation results are presented.
Stochastic local search algorithms for the graph set Tcolouring . . .
 APPROXIMATION ALGORITHMS AND METAHEURISTICS; COMPUTER AND INFORMATION SCIENCE SERIES
, 2005
"... The graph set Tcolouring problem (GSTCP) generalises the classical graph colouring problem; it asks for the assignment of sets of integers to the vertices of a graph such that constraints on the separation of any two numbers assigned to a single vertex or to adjacent vertices are satisfied and some ..."
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Cited by 16 (3 self)
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The graph set Tcolouring problem (GSTCP) generalises the classical graph colouring problem; it asks for the assignment of sets of integers to the vertices of a graph such that constraints on the separation of any two numbers assigned to a single vertex or to adjacent vertices are satisfied and some objective function is optimised. Among the objective functions of interest is the minimisation of the difference between the largest and the smallest integers used (the span). In this article, we present an experimental study of local search algorithms for solving general and large size instances of the GSTCP. We compare the performance of previously known as well as new algorithms covering both simple construction heuristics and elaborated stochastic local search algorithms. We investigate systematically different models and search strategies in the algorithms and determine the best choices for different types of instance. The study is an example of design of effective local search for constraint optimisation problems.
On the design and capacity planning of a wireless local area network
 IEEE Conference on Network Operations and Management Symposium
, 2000
"... The design of a wireless local area network (WLAN) has two major issues: determining the best placement of base stations (BS) and assigning the frequency channels for those stations. The correct BS placement minimizes installation costs. The adequate channel assignment reduces signal interference a ..."
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Cited by 15 (0 self)
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The design of a wireless local area network (WLAN) has two major issues: determining the best placement of base stations (BS) and assigning the frequency channels for those stations. The correct BS placement minimizes installation costs. The adequate channel assignment reduces signal interference and improve network throughput. This paper reports a real experience where we applied the concepts of two classical outdoor problems namely the optimal base placement problem and the fixed channel assignment problem to build a WLAN in an indoor environment.
Topological Lower Bounds for the Chromatic Number: A Hierarchy
 JAHRESBER. DEUTSCH. MATH.VEREIN
, 2004
"... Kneser's conjecture, first proved by Lovasz in 1978, states that the graph with all k element subsets of 2, . . . , n} as vertices and all pairs of disjoint sets as edges has chromatic number n2k+ 2. Several other proofs have been published (by Barany, Schrijver, Dol'nikov, Sarkari ..."
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Cited by 14 (1 self)
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Kneser's conjecture, first proved by Lovasz in 1978, states that the graph with all k element subsets of 2, . . . , n} as vertices and all pairs of disjoint sets as edges has chromatic number n2k+ 2. Several other proofs have been published (by Barany, Schrijver, Dol'nikov, Sarkaria, Krz, Greene, and others), all of them based on the BorsukUlam theorem from algebraic topology, but otherwise quite di#erent. Each can be extended to yield some lower bound on the chromatic number of an arbitrary graph. We show
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 8 (3 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.
Models and methods for frequency allocation with cumulative interference constraints
"... We consider a realistic modelling of interferences for frequency allocation in hertzian telecommunication networks. In contrast with traditional interference models based only on binary interference constraints, this new approach considers the case of a receiver disrupted simultaneously by several ..."
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Cited by 3 (2 self)
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We consider a realistic modelling of interferences for frequency allocation in hertzian telecommunication networks. In contrast with traditional interference models based only on binary interference constraints, this new approach considers the case of a receiver disrupted simultaneously by several senders yielding cumulative disruptions that are modelled through a unique nonbinary constraint. To deal with these complex constraints, we propose extensions of classical integer linear programming formulations. On a set of realistic instances provided by the CELAR, we propose several exact and heuristic solution methods including branch and cut, constraint programming, and large neighbourhood search. We also compare the performances of our best methods with those of existing heuristics and we show how the enduser benefits from using the cumulative model instead of the traditional one.
Wireless communication
"... Optimally choosing operating parameters for access points in an enterprise wireless LAN environment is a difficult and wellstudied problem. Unlike past work, the SMARTA selfmanaging wireless LAN architecture dynamically adjusts both access point channel assignments and power levels in response to ..."
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Optimally choosing operating parameters for access points in an enterprise wireless LAN environment is a difficult and wellstudied problem. Unlike past work, the SMARTA selfmanaging wireless LAN architecture dynamically adjusts both access point channel assignments and power levels in response to measured changes in the wireless environment to optimize arbitrary objective functions, while taking into account the irregular nature of RF propagation, and working with unmodified legacy clients. We evaluate the SMARTA architecture through simulation and show that our solution is not only feasible, but also provides significant improvements over existing approaches. For example, in a realistic scenario, SMARTA can provide 50 % more throughput and 40 % lower mean perpacket delay than a handoptimized configuration. Moreover, SMARTA can automatically reconfigure channels and power levels in response to both small and large changes in the RF environment due to client movement.
Complexity of different ILP models of the frequency assignment problem
, 2012
"... The frequency assignment problem (FAP) arises in wireless communication networks, such as cellular phone communication systems, television broadcasting, WLANs, and military communication systems. In all these applications, the task is to assign frequencies to a set of transmitters, subject to interf ..."
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The frequency assignment problem (FAP) arises in wireless communication networks, such as cellular phone communication systems, television broadcasting, WLANs, and military communication systems. In all these applications, the task is to assign frequencies to a set of transmitters, subject to interference constraints. The exact form of the constraints and the objective function vary according to the specific application. Integer linear programming (ILP) is widely used to solve the different flavors of the FAP. For most FAP versions, there are more than one natural ILP formulations, e.g. using a large number of binary variables or a smaller number of integer variables. A common experience with these solution techniques, as well as with NPhard optimization problems in general, is a high variance in problem complexity. Some problem instances are tremendously hard to solve optimally. There are also examples of relatively big problem instances that are nevertheless quite easy to solve. In general, it is hard to predict how long it will take to solve a given problem instance. This
Algorithms, Experimentation, Performance
"... Frequency planning is a very important task for current GSM operators. In this work we present a new mathematical formulation of the problem in which the frequency plans are evaluated by using accurate interference information coming from a real GSM network. We have developed an ant colony optimizat ..."
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Frequency planning is a very important task for current GSM operators. In this work we present a new mathematical formulation of the problem in which the frequency plans are evaluated by using accurate interference information coming from a real GSM network. We have developed an ant colony optimization (ACO) algorithm to tackle this problem. After accurately tuning this algorithm, it has been compared against a (1,10) Evolutionary Algorithm (EA). The results show that the ACO clearly outperforms the EA when using different time limits as stopping condition for a rather extensive comparison.