This paper focuses on the problem of workload placement in an InterCloud with the view of minimizing the carbon footprint of such a computing environment. In order to reduce the ecological impact of the data center Greenhouse Gas (GhG) emissions, this paper addresses the problem as a whole, by proposing a global mathematical formulation, based on the joint optimization of the Virtual Machine (VM) placement and their related traffics, along with a workload consolidation method and a cooling maximization technique that considers the dynamic behavior of the cooling fans. As the Virtual Machine Placement Problem (VMPP) is classified as an NP-hard problem, with the addition of the traffic embedding, the problem becomes more complex and stays NP-hard. Therefore, we propose a hybrid approach, for solving such problem and find good feasible solutions in a polynomial time. The results obtained from comparing with the exact method and other reference approaches help in assessing the efficiency of the proposed algorithm, as the carbon footprint costs are relatively close to the lower bound, with an average gap of about 3 percent, and found within a reasonable amount of time.

In this paper, we address the problem of Virtual Machine (VM) placement in an InterCloud with regard to the reduction of carbon footprint in such computing environment. In order to minimize data centers’ Greenhouse Gas (GhG) emissions, this paper proposes a mathematical formulation, where the placement approach is stated as a Mixed-Integer Nonlinear Programming (MINLP) problem which aims at minimizing the carbon footprint of the InterCloud. The proposed formulation presents an accurate carbon footprint evaluation based on joint optimization techniques, such as smart and performance-aware workload consolidation, along with cooling efficiency maximization, while considering the greenness factor of the data centers and the dynamic behavior of the equipment cooling fans. Simulations with an exact method showed that, compared with other baseline approaches, the proposed mathematical model leads to optimal configurations with minimal GhG emissions in a single cloud, as well as in an InterCloud environment, and can yield savings of up to 65 percent. The proposed model has also been compared with an approach that performs blind VM consolidation, and the obtained results showed that such model can simultaneously lead to VM configuration that yields the minimum carbon footprint while performing smart VM consolidation in order to prevent Service Level Agreement (SLA) violations.

This paper presents a brief review of the most important methods for node localization in Wireless Sensor Network (WSN). Among them are: Ad hoc Positioning System (APS), Anchor-Free Localization (AFL) and MoteTrack. Such methods may achieve good accuracy at the cost of extra hardware which needs to be present at each network node.

In this paper, we elaborate a set of scenarios and experiments for evaluating the impact of the physical environment on a Wireless Sensor Network (WSN). More specifically, a WSN application is implemented for collecting received signal strength indicator (RSSI) measurements in two different environments. The main contributions are twofold: boxplot diagrams are used for graphical comparison of RSSI measurements, and statistical analysis of variance (ANOVA) is performed for evaluating the impact of the physical environment on a WSN. Results analysis shows the conditions where the impact of the physical environment on a WSN is significant.

This paper proposes a mathematical model for assigning Node Bs to switches in UMTS networks, as well as an implementation of the tabu search metaheuristic for solving such a problem. In this model, the overall problem is divided into two assignment sub-problems: the assignment of a set of Node Bs to a set of radio network controllers (RNCs), and the assignment of those RNC concurrently to a set of voice switches (MSCs: Mobile Switching Centers) and a set of data switches (SGSNs: Serving GPRS Support Nodes). In order to solve the overall assignment problem, the proposed implementation defines a number of moves which enable to efficiently explore the set of possible solutions. Computational results enable to identify the parameters that are able to reduce the costs of the obtained solutions, as such costs are relatively close to the estimated lower bounds and found in reasonable computational time.

This paper proposes a new mathematical formulation to address the problem of cell assignment in UMTS network. To solve the problem, an adaptation of the tabu search metaheuristic is proposed. In this adaptation, applicable movements are well defined in order to efficiently explore the search space. Each movement has an associated gain that helps assess the degree of improvement of a current solution. Simulation results enable to evaluate the heuristic parameters that give the best solutions.

In heterogeneous wireless networks, mobile users are able to move from their home networks to different foreign networks while maintaining access capability to their subscribed services, which refers to global mobility. One of the key challenges in global mobility management is intersystem location management, which consists of keeping track of mobile users who roam into foreign networks. This paper presents an overview of mobility management in heterogeneous wireless networks and introduces a scheme which improves location management efficiency in terms of total signaling costs and intersystem paging delay. More specifically, cost reduction reaches about 50% when comparing the proposed architecture with conventional architectures.

One of the most challenging problems in global mobility management is location management which consists of keeping track of mobile users who leave their home network and roam into foreign networks that use different technologies and protocols. In this paper, we propose a model which improves location management efficiency in heterogeneous wireless networks. Such a model essentially consists of adding at the boundary location area between two different subsystems a specialized equipment called LR-ING (location register and Internetworking gateway) which is connected to the home location register (HLR) of both subsystems. Numerical results reveal that the proposed scheme enables to significantly reduce the signaling cost generated by the databases.

This paper proposes to model each cell of future wireless networks as a G/G/c/c queueing system. As such a model has not been explicitly addressed in the literature, we apply maximum entropy principles to evaluate both traffic distribution and blocking probability within each cell. Analysis of numerical results enables to specify the conditions under which the system offers good quality of service in terms of blocking probability. More specifically, such an analysis reveals that coefficient of variation of call arrivals has more impact over the blocking probability than coefficient of variation of channel holding time.

The next-generation (NG) wireless systems are envisioned to integrate the current communication systems into a seamless infrastructure, capable of allowing mobile users (MU) to access a wide range of high bandwidth wireless services. This integration of heterogeneous networks makes it difficult to locate MU as these MU move across networks using different access technologies and protocols. In this context, global roaming management constitutes a challenging problem. This paper presents an efficient approach which facilitates interoperability between heterogeneous networks during global roaming situations. Preliminary results reveal that such an approach significantly improves the performance of the NG wireless systems in terms of generated signaling traffic and response time during the global roaming process.

The "explosive growth in bursty traffic" changes the network dynamics and requires a good evaluation of various classes of service when designing an access network. From a topological standpoint, the multiservice networks in this paper are heterogeneous systems which integrate both a core and some wireless access networks into an infrastructure similar to third-generation wireless networks. Such networks require reliable and cost-effective solutions to the problem of selecting access technologies for satisfying performance and quality of service requirements related to the services and applications envisioned. This paper analyzes the reliability aspects of some access network topologies to insure a certain level of quality of service at the lowest cost for the end users. It considers a mass market equivalent to 1.6 million subscribers, the objective being to determine the cost the users are ready to pay to benefit from services and applications provided by these multiservice networks. For these purposes, the relative behavior of 3 access-network topologies are studied: the tree with parallel backup links, the ring, and the partially meshed topologies. In ring topology, simulation results show that a great connectivity in the access network is not justified in terms of reliability requirements; the partially meshed topology, even if it has redundant links which affect its cost, outperforms the tree with parallel backup links; and the ring topology is more reliable in terms of disconnected sessions than the tree topology. By considering both reliability and cost, a tree with parallel backup links appears the best topology for the access network and its cost is acceptable for the end user. This study can be extended by: (1) establishing the cost as a function of the quality of service; (2) optimizing the partially meshed topology for more reliable networks; and (3) defining a (shaping) policy to deal with a variety of traffic schemes.

As the speed and number of LANs continue to increase higher and higher demand is placed on wide area networks. To support the tremendous traffic and to avoid link congestion, such networks should utilize a robust routing strategy. This paper proposes a routing algorithm called MINDEL for assigning flows to distributed network links. With polynomial complexity this algorithm tends to minimize each packet delay by avoiding as much as possible the congested routes. Numerical results confirm the efficiency of such an algorithm, particularly for large networks, which convinces us that it could be efficiently used in high-speed networks.