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Channel assignment and graph multicoloring
, 2002
"... Cellular data and communication networks are usually modeled as graphs with each node representing a base station in a cell in the network, and edges representing geographical adjacency of cells. The problem of channel assignment in such networks can be seen as a graph multicoloring problem. We surv ..."
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Cellular data and communication networks are usually modeled as graphs with each node representing a base station in a cell in the network, and edges representing geographical adjacency of cells. The problem of channel assignment in such networks can be seen as a graph multicoloring problem. We survey the models, algorithms, and lower bounds for this problem.
The hierarchical model for load balancing on two machines
"... Following previous work, we consider the hierarchical load balancing model on two machines
of possibly di®erent speeds. We ¯rst focus on maximizing the minimum machine load and show
that no competitive algorithm exists for this problem. We overcome this barrier in two ways,
both related to previousl ..."
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Following previous work, we consider the hierarchical load balancing model on two machines
of possibly di®erent speeds. We ¯rst focus on maximizing the minimum machine load and show
that no competitive algorithm exists for this problem. We overcome this barrier in two ways,
both related to previously known models. The ¯rst one is fractional assignment, where each job
can be arbitrarily split between the machines. The second one is a semionline model where the
sum of jobs is known in advance. We design algorithms of best possible competitive ratios for
both these cases. Furthermore, we show that the combination of the two models leads to the
existence of an optimal algorithm (i.e., an algorithm of competitive ratio 1). This algorithm
is clearly optimal for the makespan minimization problem as well. For the latter problem, we
consider the fractional assignment model and design an algorithm of best possible competitive
ratio for it.
A multifrequency mac specially designed for wireless sensor network applications
 ACM Transactions in Embedded Computing Systems
"... Multifrequency media access control has been well understood in general wireless ad hoc networks, while in wireless sensor networks, researchers still focus on single frequency solutions. In wireless sensor networks, each device is typically equipped with a single radio transceiver and applications ..."
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Multifrequency media access control has been well understood in general wireless ad hoc networks, while in wireless sensor networks, researchers still focus on single frequency solutions. In wireless sensor networks, each device is typically equipped with a single radio transceiver and applications adopt much smaller packet sizes compared to those in general wireless ad hoc networks. Hence, the multifrequency MAC protocols proposed for general wireless ad hoc networks are not suitable for wireless sensor network applications, which we further demonstrate through our simulation experiments. In this article, we propose MMSN, which takes advantage of multifrequency availability while, at the same time, takes into consideration the restrictions of wireless sensor networks. In MMSN, four frequency assignment options are provided to meet different application requirements. A scalable media access is designed with efficient broadcast support. Also, an optimal nonuniform
Optimal Semionline Scheduling Algorithms on Two Parallel Identical Machines under a Grade of Service Provision
"... Abstract. This paper investigates semionline scheduling problems on two parallel identical machines under a grade of service (GoS) provision. We consider two different semionline versions where the optimal offline value of the instance is known in advance or the largest processing time of all jobs ..."
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Abstract. This paper investigates semionline scheduling problems on two parallel identical machines under a grade of service (GoS) provision. We consider two different semionline versions where the optimal offline value of the instance is known in advance or the largest processing time of all jobs is known in advance. Respectively for two semionline problems, we develop algorithms with competitive ratios of 3/2 and ( √ 5+1)/2, whichareshowntobeoptimal.
The dynamic frequency assignment problem
 European Journal of Operational Research
, 2009
"... In this paper, we consider a frequency assignment problem occurring in a military context. The main originality of the problem pertains to its dynamic dimension: new communications requiring frequency assignments need to be established throughout a deployment. The problem decomposes in three phase ..."
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In this paper, we consider a frequency assignment problem occurring in a military context. The main originality of the problem pertains to its dynamic dimension: new communications requiring frequency assignments need to be established throughout a deployment. The problem decomposes in three phases: assignment of an initial kernel of communications, dynamic assignment of new communication links and reparation when no assignment is possible. Different solution methods are proposed and many computational tests are carried out on realistic instances.
Online load balancing made simple: Greedy strikes back
 Journal of Discrete Algorithms
, 2003
"... We provide a new simpler approach to the online load balancing problem in the case of restricted assignment of temporary weighted tasks. The approach is very general and allows to derive online distributed algorithms whose competitive ratio is characterized by some combinatorial properties of the ..."
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We provide a new simpler approach to the online load balancing problem in the case of restricted assignment of temporary weighted tasks. The approach is very general and allows to derive online distributed algorithms whose competitive ratio is characterized by some combinatorial properties of the underlying graph representing the problem.
Optimal Online Algorithms on Two Hierarchical Machines with Resource Augmentation
"... Abstract. This paper investigates an online hierarchical scheduling problem with resource augmentation, i.e., the resources of the online algorithms are different from those of the offline algorithms. The machines are provided with different capacity according to their hierarchies. One with the hier ..."
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Abstract. This paper investigates an online hierarchical scheduling problem with resource augmentation, i.e., the resources of the online algorithms are different from those of the offline algorithms. The machines are provided with different capacity according to their hierarchies. One with the hierarchy 1 has a speed of s (q) in the online (offline) algorithms and can process all the jobs. The other with hierarchy 2 has a speed of 1 in the online/offline algorithms and can only process partial jobs. The objective is to minimize makespan. For any 0 <q,s<∞, wepresent optimal online algorithms with parametric competitive ratios. 1
A Mathematical Programming Approach for Online Hierarchical Scheduling
"... Abstract. This paper considers an online hierarchical scheduling problem on parallel identical machines. We are given a set of m machines and a sequence of jobs. Each machine has a different hierarchy, and each job also has a hierarchy associated with it. A job can be assigned to a machine only if i ..."
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Abstract. This paper considers an online hierarchical scheduling problem on parallel identical machines. We are given a set of m machines and a sequence of jobs. Each machine has a different hierarchy, and each job also has a hierarchy associated with it. A job can be assigned to a machine only if its hierarchy is no less than that of the machine. The objective is to minimize makespan. Two models are studied in the paper. For the fractional model, we present an improved algorithm and lower bounds. Both algorithm and lower bounds are based on solutions of mathematical programming. For any given m, our algorithm is optimal by numerical calculation. For the integral model, we present both a general algorithm for any m, and an improved algorithm with better competitive ratios of 2.333 and 2.610 for m = 4 and 5, respectively. 1
Genetic Tabu search for robust fixed channel assignment under dynamic traffic data
, 2011
"... The contribution of this work is twofold. Firstly, we introduce a new channel assignment model for GSM radio networks. In this model both spatial and temporal variations of traffic are taken into account in order to improve network capacity and robustness. Secondly, using this model, we develop an ..."
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The contribution of this work is twofold. Firstly, we introduce a new channel assignment model for GSM radio networks. In this model both spatial and temporal variations of traffic are taken into account in order to improve network capacity and robustness. Secondly, using this model, we develop an original and effective hybrid algorithm to get high quality frequency plans. This algorithm combines a problem specific crossover and a Tabu search procedure. The proposed model and hybrid algorithm are evaluated using both artificial and real data. Computational results allow us to confirm the effectiveness of the proposed approach.