International audience

The increasing demand for real-time, resource-efficient deep learning models has driven research into frugal object detection techniques, enabling deployment in edge computing, IoT, and mobile applications. This paper comprehensively reviews lightweight object detection architectures, including CNN-based, transformer-based, and hybrid models. It explores optimization techniques such as knowledge distillation, quantization, pruning, and neural architecture search (NAS). We analyze trade-offs between accuracy, computational efficiency, and power consumption and providing insights into their impact on various edge AI hardware platforms, including Jetson Nano, Google Edge TPU, and FPGA-based deployments. A comparative evaluation highlights the strengths and limitations of different frugal optimization strategies, emphasizing hybrid approaches that balance detection performance and efficiency. We also discuss challenges such as cross-hardware generalization, real-time adaptability, adversarial robustness, and explainability. Finally, we outline promising future research directions, including advancements in energy-efficient vision transformers, on-device continual learning, adaptive compression techniques, and sustainable AI solutions. This study serves as a roadmap for researchers and practitioners developing efficient object detection models for resource-constrained environments.

Unmanned Aerial Vehicles (UAVs) have seen extensive growth in both civilian and military sectors, driven by their versatility, ease of deployment, and expanding range of applications. However, this expansion has also exposed UAV systems to a growing number of cybersecurity threats. The MAVLink protocol, widely adopted for UAV-ground station communication, lacks native encryption, making it susceptible to interception and manipulation. This paper proposes a comprehensive solution based on the use of Hardware Security Modules (HSMs) to protect cryptographic keys and secure data transmission using the ChaCha20 encryption algorithm. Our approach integrates the HSM into the drone system, ensuring that sensitive keys are securely generated, stored, and accessed. We present the architecture, implementation details, and simulation results that confirm the feasibility and efficiency of the proposed solution, highlighting its potential to significantly enhance the security of UAV communications with minimal performance overhead.

The aim of this paper is to introduce a new Internet generation designed for 6G readiness. The 6G architecture is envisioned to rely on trust zones, termed as 'Edges'. Each Edge comprises nodes that incorporate small-scale data centers, enabling a significant portion of 6G queries to be processed locally. This local setup introduces distributed data centers within the Edge nodes that can be as small as embedded into a smartphone and facilitates serverless functions. Edge nodes proliferation offers 6G to create a new kind of infrastructure where nearby edge nodes can be accessed directly, in Device-to-Device (D2D) mode, rather than via the traditional vertical Internet architecture. 6G will therefore be made up of vertical, long-distance communications and short, horizontal distribution channels. The vertical aspect of the network is represented by the telecommunication operator’s infrastructure, which provides secure channels between trust zones. The horizontal network is a new domain addressed by both incumbent players and new entrants called the Internet of Edges [6]. The 'Cloud Continuum' encapsulates both horizontal and vertical networks. 6G like Internet of Edges infrastructure has been developed, tested, and is currently being commercialized by Green Communications.

Virtual Machine (VM) migration presents several advantages for both cloud operators and cloud users. The benefits of VM migration are amplified in the context of Joint-clouds, in which multiple clouds owned by distinct operators exchange VMs. However, inter-cloud VM migrations might require the usage of the Internet, which creates the possibility of external threats and therefore, a risk to the VMs' integrity. Thus, we propose a novel approach to secure VM migration for Joint-clouds. We consider both local migration and inter-cloud migration. Our solution is based on a multi-blockchain system, in which each cloud provider participates in the maintenance of a consortium blockchain to store relevant information about the migrations. In addition, each cloud operator might choose to keep a local blockchain to secure its local VM migrations. Therefore, inter-blockchain communication plays an important role in our work.

Summary Late detection of security breaches increases the risk of irreparable damages and limits any mitigation attempts. We propose a fast and accurate threat detection and prevention architecture that combines the advantages of real‐time streaming with batch processing over a historical database. We create a dataset by capturing both legitimate and malicious traffic and propose two ways of combining packets into flows, one considering a time window and the other analyzing the first few packets of each flow per period. We also investigate the effectiveness of our proposal on real‐world network traces obtained from a significant Brazilian network operator providing broadband Internet to their customers. We implement and evaluate three classification algorithms and two anomaly detection methods. The results show an accuracy higher than 95% and an excellent trade‐off between attack detection and false‐positive rates. We further propose an improved scheme based on software defined networks that automatically prevents threats by analyzing only the first few packets of a flow. The proposal promptly and efficiently blocks threats, is robust, and can scale up, even when the attacker employs spoofed IP.

The paradigm of Internet of Vehicles (IoV) as an extension to the Internet of Things (IoT) concept can assist the development of smart cities. IoV relies on vehicular communications to allow vehicles to communicate in real time with other vehicles, roadside infrastructure, and pedestrians. The main goal is to enable not only road safety services but also time-constrained IoT applications. In this context, Cellular Vehicle-to-Everything (C-V2X) communication is a prominent technology to accomplish IoV goals. Currently, there are two versions of C-V2X available, long-term evolution-V2X (LTE-V2X) and new radio-V2X (NR-V2X), and in both, mechanisms of resource allocation (RA) play an important role in their performance. Therefore, our goal in this article is to present an extensive state of the art of RA on C-V2X technology. Thus, we first present the main technical aspect related to LTE-V2X and NR-V2X technologies. Afterward, we present and categorize the related works for both technologies, pointing out their main differences, advantages, and drawbacks. Finally, we present the challenges, open issues, and future technical trends related to RA in C-V2X.

Summary The late detection of security threats causes a significant increase in the risk of irreparable damages and restricts any defense attempt. In this paper, we propose a sCAlable TRAffic Classifier and Analyzer (CATRACA). CATRACA works as an efficient online Intrusion Detection and Prevention System implemented as a Virtualized Network Function. CATRACA is based on Apache Spark, a Big Data Streaming processing system, and it is deployed over the Open Platform for Network Functions Virtualization (OPNFV), providing an accurate real‐time threat‐detection service. The system presents a friendly graphical interface that provides real‐time visualization of the traffic and the attacks that occur in the network. Our prototype can differentiate normal traffic from denial of service (DoS) attacks and vulnerability probes over 95% accuracy under three different datasets. Moreover, CATRACA handles streaming data under concept drift detection with more than 85% of accuracy.

The throughput supported by network interfaces can be hardly followed by the packet processing speed in software. The processing rate is bounded due to the overheads imposed by the architecture of the network stack. For this reason, multiple research proposals try to offload packet processing on different types of hardware like GPUs and FPGAs. In this paper we present an architecture which offloads the data plane packet processing on a programmable hardware with parallel processing capability. For this purpose, we use the MPPA (Massively Parallel Processor Array) smart NIC from Kalray which offers the ODP API that can be used for packet processing. Our goal is to build a full mesh non-blocking layer 2 network. We implemented a TRILL protocol on the MPPA processor, which can be used as a basis for fabric network, but some other protocol may be used as well. Our performance evaluation shows that we can process TRILL frames at full-duplex line-rate (up to 40Gbps) for different packet sizes while reducing latency.

Attackers create new threats and constantly change their behavior to mislead security systems. In this paper, we propose an adaptive threat detection architecture that trains its detection models in real time. The major contributions of the proposed architecture are: i) gather data about zero-day attacks and attacker behavior using honeypots in the network; ii) process data in real time and achieve high processing throughput through detection schemes implemented with stream processing technology; iii) use of two real datasets to evaluate our detection schemes, the first from a major network operator in Brazil and the other created in our lab; iv) design and development of adaptive detection schemes including both online trained supervised classification schemes that update their parameters in real time and learn zero-day threats from the honeypots, and online trained unsupervised anomaly detection schemes that model legitimate user behavior and adapt to changes. The performance evaluation results show that proposed architecture maintains an excellent trade-off between threat detection and false positive rates and achieves high classification accuracy of more than 90%, even with legitimate behavior changes and zero-day threats.

Topology discovery is one of the most critical tasks of Software-Defined Network (SDN) controllers. Current SDN controllers use the OpenFlow Discovery Protocol (OFDP) as the de-facto protocol for discovering the underlying network topology. In a previous work, we have shown the functional, performance and security limitations of OFDP. In this paper, we introduce and detail a novel protocol called secure and efficient OpenFlow Discovery Protocol sOTDP. sOFTDP requires minimal changes to OpenFlow switch design, eliminates major vulnerabilities in the topology discovery process and improves its performance. We have implemented sOFTDP as a topology discovery module in Floodlight for evaluation. The results show that our implementation is more secure than OFDP and previous security workarounds. Also, sOFTDP reduces the topology discovery time several orders of magnitude compared to the original OFDP and existing OFDP improvements.

This paper presents NeuTM, a framework for network Traffic Matrix (TM) prediction based on Long Short-Term Memory Recurrent Neural Networks (LSTM RNNs). TM prediction is defined as the problem of estimating future network traffic matrix from the previous and achieved network traffic data. It is widely used in network planning, resource management and network security. Long Short-Term Memory (LSTM) is a specific recurrent neural network (RNN) architecture that is well-suited to learn from data and classify or predict time series with time lags of unknown size. LSTMs have been shown to model longrange dependencies more accurately than conventional RNNs. NeuTM is a LSTM RNN-based framework for predicting TM in large networks. By validating our framework on real-world data from GEANT network, we show that our model converges quickly and gives state of the art TM prediction performance.

This paper introduces NeuRoute, a dynamic routing framework for Software Defined Networks (SDN) entirely based on machine learning, specifically, Neural Networks. Current SDN/OpenFlow controllers use a default routing based on Dijkstra's algorithm for shortest paths, and provide APIs to develop custom routing applications. NeuRoute is a controller-agnostic dynamic routing framework that (i) predicts traffic matrix in real time, (ii) uses a neural network to learn traffic characteristics and (iii) generates forwarding rules accordingly to optimize the network throughput. NeuRoute achieves the same results as the most efficient dynamic routing heuristic but in much less execution time.

Energy consumption has become a key issue in the design of communication systems. Indeed, both for economic and green reasons, the concept of energy saving appears at an early stage of projects, fully integrating the list of expected performance, as well as throughput or security. In multihop wireless networks, several energy-aware approaches have been proposed with specific goals, such as network's lifetime or stability. To reduce the global energy consumption of such networks, we proposed in a previous work an optimal solution with interference consideration, based on mixed integer linear programming, to route a set of flows over a minimal number of nodes. Thus, without degrading flow rates, inactive nodes can be put in a sleep mode or be turned off to maximize energy savings. Indeed, the energy consumption related to communication is just a fraction of the total consumption of a node In this article, we are going a step further, by providing a metric to efficiently aggregate flows with classical shortest path algorithms. Thanks to a theoretical comparison and simulations, we demonstrate the significant gains can be obtained with our approach. Finally, we discuss on ways to implement our solution in existing routing protocols, in a fully distributed manner, and other considerations that may need to take on.

The number of devices connected through the Internet of Things (IoT) will significantly grow in the next few years while security of their interconnections is going to be a major challenge. For many devices in IoT scenarios, the necessary resources to send and receive bytes are extremely high and when such devices are powered with battery the amount of exchanged bytes directly impacts their life time. As a result, compression of existing protocols is a widely accepted technique to make IoT benefit from the protocols developed over the last decades. This paper presents ESP Header Compression (EHC), a framework that enables compression of packets protected with Encapsulating Security Payload (ESP). EHC is composed of EHC Rules, targeting the compression of a specific field and organized according to EHC Strategies. Further, the paper presents Diet-ESP, an EHC Strategy that highly reduces the networking overhead of ESP packets to address the IoT security and bandwidth requirements. Diet-ESP results in sending fewer bytes which in turn reduces the number of required radio frames and thus battery consumption. The measurements showed that sending 10 byte application data on IEEE 802.15.4 radio networks secured with the standard ESP requires sending an additional frame. This results into a 95% energy overhead compared to the unprotected data, while Diet-ESP results only in a 3% overhead compared to unprotected data. This small overhead is achievable with some compressions being performed within the ESP stack which requires altering the same. Nevertheless, Diet-ESP remains fully security compliant to ESP and performs better than any other compression framework as far as ESP is considered.

Over recent years, packet processing acceleration has become a hot topic. Indeed, several software solutions have been developed to offer the best possible performance. Recently, a new open source project has started called OpenDataPlane (ODP), this framework provides a set of APIs, configuration files, and other functions to accelerate packet processing and manage effectively the networking data plane. In this paper, we present our new Xen architecture, implemented within Metamorphic Networks "MNet" platform that integrates ODP in a privileged domain, called driver domain. This architecture allows us to associate ODP with virtual CPU cores in order to accelerate packet processing and improve the performance of our platform, without adding overhead in physical processors. The results of our experiments show that our new architecture improves packet processing performance by 15%, only using the virtual CPU resources.

Software-Defined Networking (SDN) controllers are considered as Network Operating Systems (NOSs) and often viewed as a single point of failure. Detecting which SDN controller is managing a target network is a big step for an attacker to launch specific/effective attacks against it. In this paper, we demonstrate the feasibility of fingerpirinting SDN controllers. We propose techniques allowing an attacker placed in the data plane, which is supposed to be physically separate from the control plane, to detect which controller is managing the network. To the best of our knowledge, this is the first work on fingerprinting SDN controllers, with as primary goal to emphasize the necessity to highly secure the controller. We focus on OpenFlow-based SDN networks since OpenFlow is currently the most deployed SDN technology by hardware and software vendors.

Cloud computing and Network Function Virtualization (NFV) represent together a promising solution for wireless network operators to improve business agility and cope with the continuing growth in data traffic. Furthermore, the use of edge clouds in association with a centralized cloud, referred to as the edge-central cloud, notably improves user experience while ensuring scalability and load balancing. In such carrier cloud environment, efficient management mechanisms for the Virtualized Network Functions (VNFs) are of crucial importance. In this paper, we introduce VNF placement and provisioning optimization strategies over an edge- central carrier cloud infrastructure taking into account Quality of Service (QoS) requirements (i.e., response time, latency constraints and real-time requirements) and using queuing and QoS models. Our main design goals are to optimize resource utilization, to prevent cloudlet overload, and to avoid violation of Service Level Agreement (SLA) requirements. Through extensive simulations, we show how a trade-off can be achieved between these conflicting objectives.

In this paper, we propose a novel 3D Underwater Wireless Sensor Network Deployment scheme for solid detection in rivers. Our objective is to minimize the number of deployed underwater sensors within a target field installation while ensuring i) the required Quality of Monitoring (QoM) (i.e., differentiated probabilistic detection) and ii) wireless network connectivity. To generate the best topology, we propose a novel deployment heuristic, named 3D-UWSN-Deploy, based on a subcube tessellation of the monitored field installation and a mixed integer linear program optimization. To gauge the effectiveness of 3D-UWSN-Deploy, we compare it with the most prominent related strategies. Simulation results show that our proposal is scalable and obtains the best performance in terms of cost deployment, quality of monitoring and connectivity.

Control plane distribution on Software Defined Networking enhances security, performance and scalability of the network. In this paper, we propose an efficient architecture for distribution of controllers. The main contributions of the proposed architecture are: i) A controller distributed areas to ensure security, performance and scalability of the network; ii) A single database maintained by a designated controller to provide consistency to the control plane; iii) An optimized heuristic for locating controllers to reduce latency in the control plane; iv) A resilient mechanism of choosing the designated controller to ensure the proper functioning of the network, even when there are failures. A prototype of the proposal was implemented and the placement heuristic was analyzed in real topologies. The results show that connectivity is maintained even in failure scenarios. Finally, we show that the placement optimization reduces the average latency of controllers. Our proposed heuristic achieves a fair distribution of controllers and outperforms the network resilience of other heuristics up to two times better.

Network Function Virtualisation (NFV) represents a promising solution for wireless network operators to improve business agility and cope with the continuing growth in data traffic. Furthermore, by virtualizing core network functions as well as radio-access network functions, NFV can effectively reduce the cost to deploy and operate large wireless networks. Face to this technology revolution, a new underlying cloud architecture is emerging. This architecture is based on the combination of edge clouds and a centralized cloud, referred to as the edge-central cloud. This notably improves user experience while ensuring scalability and load balancing. In such carrier cloud environment, efficient management mechanisms for the Virtual Network Functions (VNFs) are of crucial importance. In this paper, we introduce VNF placement and provisioning optimization strategies over an edge-central carrier cloud infrastructure taking into account QoS requirements (i.e., response time, latency constraints and real-time requirements) and using analytical and QoS models. Our main design goals are to optimize resource utilization, to prevent cloudlet overload, and to avoid violation of SLA requirements. We propose different solutions to achieve a trade-off between these conflicting objectives according to the wireless operator requirements. These solutions are evaluated through extensive simulations using different performance metrics and encouraging results are obtained.

In this paper, we propose a new approach for optimizing the handoff decision in femtocell networks using Hidden Markov Model. To do so, we formulate the handoff problem as an optimization problem whose objective is to find the best Femtocell Access Point (FAP) assignment strategy that minimizes the number of unnecessary handoffs while maintaining a good quality of wireless communications. We have used Hidden Markov Model prediction tools to predict the target FAP by observing the geographic positions of the mobile. To evaluate the effectiveness of our proposal, we conducted extensive simulations. Results show that our proposed approach minimizes the number of handoffs by up to 7 times and enhances the dwell time in the FAP by up to 42% in comparison with others handoff decision making strategies commonly used in related cellular modeling works.

Several works in the literature show that accurate estimations of the actual One-Way Delays (OWD) could improve the performance of various network protocol, such as Transport Control Protocol (TCP) throughput. With the emergence of multipath transport protocols like Multipath TCP or the Stream Control Transport Protocol (SCTP), the potential impact can be even higher. Indeed, as multipath transport protocols send data concurrently on heterogeneous paths, the knowledge of corresponding OWDs can greatly help mitigating packet arrival disorder. Theoretically, clock synchronization protocols between endpoints could ensure OWD knowledge, but their efficiency at the Internet scale is debatable. In practice, TCP uses the Round Trip Time (RTT) to take into account congestion or to compute retransmission timeouts, and the OWD is assumed to be half the RTT. However, numerous studies show that a majority of Internet connections experience latency asymmetry. In this paper, we propose a technique based on differential pacing over multiple paths to obtain an estimation of the difference in OWDs between the different paths, motivated by its strong utility for multipath transport protocols such as MPTCP and SCTP. Simulations show which are the interesting scenarios of application.

In this paper, we propose a new 2-Dimensional Underwater Barrier Deployment Algorithm (2D-UBDA) ensuring the barrier detection of toxic substances in a river. Our objective is to guarantee a full detection of chemical pollutant sources, while minimizing the deployment cost. To achieve this, first 2D-UBDA determines the potential deployment areas within a predefined target field installation and this, for each pollution source, by using a 3D-propagation model of a substance to predict its molarity in any point within the river. Then, based on an integer linear programming algorithm, 2D-UBDA selects the minimum number of sub-areas in which chemical sensors will be deployed by taking into consideration the intersections between the potential deployment zones of all pollution sources located upstream of the target field installation. To validate our proposal, the Pamplonita river located in Amazon rainforest is used as a case of study. Based on extensive simulations, 2D-UBDA outperforms the basic deployment strategies in terms of number of chemical sensors and successful detection of pollutant.

Femtocells are emerging as a key technology to improve coverage and network capacity in indoor environments. When femtocells use different frequency bands than macrocells (i.e., split-spectrum approach), femto-to-femto interference remains the major issue. In particular, congestion cases in which femtocell demands exceed the available resources raise several challenging questions: how much a femtocell can demand? how much it can obtain? and how this shall depends on the interference with its neighbors? Strategic interference management between femtocells via power control and resource allocation mechanisms is needed to avoid performance degradation during congestion cases. In this paper, we model the resource and power allocation problem as an operations research game, where imputations are deduced from cooperative game theory, namely the Shapley value and the Nucleolus, using utility components results of partial optimizations. Based on these evaluations, users' demands are first rescaled to strategically justified values. Then, a power-level and throughput optimization using the rescaled demands is conducted. The performance of the developed solutions is analyzed and extensive simulation results are presented to illustrate their potential advantages. In particular, we show that the Shapley value solution with power control offers the overall best performance in terms of throughput, fairness, spectrum spatial reuse, and transmit power, with a slightly higher time complexity compared to alternative solutions.

Recent studies have shown that the energy consumption of wireless access networks is a threat to the sustainability of mobile cloud services. Consequently, energy efficient solutions are becoming crucial for both local and wireless access networks. In this paper, we propose a flow-based management framework to achieve energy efficiency in campus networks. We address the problem from the dynamic perspective, where users come and leave the system in an unpredictable way. Specifically, we propose an online flow-based routing approach that allows dynamic reconfiguration of existing flows as well as dynamic link rate adaptation, while taking into account users' demands and mobility. Our approach is compliant with the emerging software defined networking (SDN) paradigm since it can be integrated as an application on top of an SDN controller. To achieve this, we first formulate the flow-based routing problem as an integer linear program (ILP). As this problem is known to be NP-hard, we then propose a simple yet efficient ant colony-based approach to solve the formulated ILP. Through extensive simulations, we show that our proposed approach is able to achieve significant gains in terms of energy consumption, compared to heuristic solutions and conventional routing solutions such as the shortest path (SP) routing, the minimum link residual capacity routing metric (MRC), and the load balancing (LB) scheme. In particular, we show that the energy consumption can be reduced by up to 7%, 35%, 44%, and 49% compared to Greedy-OFER, MRC, SP, and LB, respectively, while ensuring the required quality of service (QoS).

With the massive adoption of cloud-based services, high energy consumption and carbon footprint of cloud infrastructures have become a major concern in the IT industry. Consequently, many governments and IT advisory organizations have urged IT stakeholders (i.e., cloud provider and cloud customers) to embrace green IT and regularly monitor and report their carbon emissions and put in place efficient strategies and techniques to control the environmental impact of their infrastructures and/or applications. Motivated by this growing trend, we investigate, in this paper, how cloud providers can meet Service Level Agreements (SLAs) with green requirements. In such SLAs, a cloud customer requires from cloud providers that carbon emissions generated by the leased resources should not exceed a fixed bound. We hence propose a resource management framework allowing cloud providers to provision resources in the form of Virtual Data Centers (VDCs) (i.e., a set of virtual machines and virtual links with guaranteed bandwidth) across a geo-distributed infrastructure with the aim of reducing operational costs and green SLA violation penalties. Extensive simulations show that the proposed solution maximizes the cloud provider's profit and minimizes the violation of green SLAs.

The increasing adoption of server virtualization has recently favored three key technology advances in data-center networking: the emergence at the hypervisor software level of virtual bridging functions between virtual machines and the physical network; the possibility to dynamically migrate virtual machines across virtualization servers in the data-center network (DCN); a more efficient exploitation of the large path diversity by means of multipath forwarding protocols. In this paper, we investigate the impact of these novel features in DCN optimization by providing a comprehensive mathematical formulation and a repeated matching heuristic for its resolution. We show, in particular, how virtual bridging and multipath forwarding impact common DCN optimization goals, traffic engineering (TE) and energy efficiency (EE), and assess their utility in the various cases of four different DCN topologies. We show that virtual bridging brings a high performance gain when TE is the primary goal and should be deactivated when EE becomes important. Moreover, we show that multipath forwarding can bring relevant gains only when EE is the primary goal and virtual bridging is not enabled.

Nowadays, LTE-based femtocell technology is a promising solution offering high-speed services, enhanced indoor coverage and increased system capacity. In such multi-user wireless communication systems, intelligently allocating resources is the substantial aim towards interference mitigation and enhancing power and spectral efficiencies. In this paper, we propose a joint power and channel allocation with Adaptive Modulation and Coding (AMC) technique for downlink OFDMA-based LTE system, namely AMC-QRAP. As trade-off between distributed and centralized architectures, we consider a clustered network architecture. Users differentiation is taken into account to ensure Quality of Service (QoS) guarantee where premium High Priority HP users and best effort BE users are served by the network. Our allocation problem is resolved as an optimization model using linear programming. Extensive simulations prove that our proposal outperforms different techniques in the literature and considerably improve two previously proposed methods QP-FCRA and Q-FCRA. We consider different metrics for performance evaluation such as spectral efficiency, throughput satisfaction rate, user outage and transmission power.

Cars cruising for parking adds a non negligible amount to traffic congestion and CO2pollution. Hence, good parking management policies are required to reduce such discomfort. In this paper, we address this problem from two sides. First, we consider how local parking authorities called parking coordinators (PC) can optimize the distribution of the slots they manage through a full cooperation between them. Second, we model the problem as a congestion game, where vehicles act as players who will eventually choose the best parking garage for them, while minimizing the whole network cost. We study the effectiveness of both schemes (i.e, PC-aware and game theoretic approaches) in various contexts and compare them with the reference centralized model as well as a greedy approach. Simulation results show that our proposals provide high request satisfaction ratio, close to the optimal baseline approach and outperform the greedy method up to 30%, while ensuring a fair distribution of slots through the network.

The security of large applications and distributed systems is heavily dependent on Identity Management models and infrastructures. In this paper we introduce the Identity Management approach developed in the SecFuNet project, which emphasizes the use of smartcards to user authentication and user-centric attribute delivery policies. In current identity models, user attributes are stored in identity providers and any trust relationship may spread user information across trust networks formed among identity providers. In our approach, the user controls the release of his attributes that are stored in his own smartcard. Also, the approach makes use of secure elements and virtualization for protecting user information. This paper describes aspects of our authentication model and discusses the results obtained with a prototype implementation.

Recently, LTE-based femtocell system has received significant attention as a promising solution offering high-speed services, enhanced indoor coverage and increased system capacity. Intelligently allocate resources in multi-user OFDMA-based network is the substantial aim towards interference mitigation and enhancing power and spectral efficiencies. In this paper, we propose a downlink joint resource allocation with Adaptive Modulation and Coding (AMC) technique for such system, namely AMC-QRAP. The proposal core is adjusting the transmission link to the channel status and users demand through the power control and suitable selection of the modulation/coding scheme. Clustered network is adopted and users differentiation is considered providing Quality of Service (QoS) in the network. Our resolution model is solved as an optimization problem using the linear programming. We show through extensive simulations the outperformance of our method compare to different state-of-the-art methods using different evaluation metrics.

Firewalls are the first defense line for the networking services and applications. With the advent of virtualization and Cloud Computing, the explosive growth of network-based services, investigations have emphasized the limitations of conventional firewalls. However, despite of being impressively significant to improve security, cloud-based firewalling approaches still experience severe performance and reliability issues that can lead to non use of these services by companies. Hence, our work presents an efficient architecture to manage performance and reliability on a hybrid cloud-based firewalling service. Being composed of a physical and a virtual part, the architecture follows an approach that supports and complements basic physical firewall functionalities with virtual ones. The architecture was deployed and experimental results show that the proposed approach improve the computational power of traditional firewall with the support of cloud-based firewalling service.

A present issue in the evolution of mobile cellular networks is determining whether, how and where to deploy adaptive content and cloud distribution solutions at the base station and backhauling network level. Intuitively, an adaptive placement of content and computing resources in the most crowded regions can grant important traffic offloading, improve network efficiency and user quality of experience. In this paper we document the content consumption in the Orange cellular network for the Paris metropolitan area, from spatial and application-level extensive analysis of real data from a few million users, reporting the experimental distributions. In this scope, we propose a hotspot cell estimator computed over user's mobility metrics and based on linear regression. Evaluating our estimator on real data, it appears as an excellent hotspot detection solution of cellular and backhauling network management. We show that its error strictly decreases with the cell load, and it is negligible for reasonable hotspot cell load upper thresholds. We also show that our hotspot estimator is quite scalable against mobility data volume and against time variations.

The Security for the Future Networks (SecFuNet) project proposes to integrate the secure microcontrollers in order to introduce, among its many services, authentication and authorization functions for Cloud and virtual environments. One of the main goals of SecFuNet is to develop a secure infrastructure for virtualized environments and Clouds in order to provide strong isolation among virtual infrastructures, and guarantee that one virtual machine (VM) should not interfere with others. The goal of this paper is to describe the implementation and the experimentation of the solution for identifying users and nodes in the SecFuNet architecture. In this implementation, we also employ low-cost smartcards. Only authorized users are allowed to create or instantiate virtual environments. Thus, users and hypervisors are equipped with secure elements, used to open TLS secure channels with strong mutual authentication.

Researchers agree on a basic, general and abstract definition that mobile cloud computing is a combination of mobile and cloud computing. Nevertheless, the location of the computation power is still controversial and varies from centralized servers located somewhere in the internet to a collection of mobile devices interested in processing certain tasks. Interestingly, all mobile cloud architectures tried to meet the expectations of mobile cloud through application layer solutions. Although of its innovation, mobile networks' physical layer is not optimized for similar applications, thus it affects the system's overall performance and cause mobile cloud architectures to fail in satisfying its goals such as increase in delay, increase in battery consumption etc. In this paper, we will discuss mobile cloud from telecommunication perspective to harmonize the physical layer of mobile networks (LTE and UMTS) with the application layer by proposing an innovative architecture. This new architecture keeps the mobile operator at the core of mobile cloud computing and offers revenue-making business model that motivates the operator to invest in this technology.

In lossy environment like wireless networks, random losses are treated by TCP as signals of congestion and TCP cuts down the sending rate, leading to the performance degradation. The practical network coding system TCP/NC can address this problem. TCP/NC masks the random losses by allowing the destination to acknowledge every degree of freedom even though original data is not decoded yet. Consequently, TCP smoothly reacts to random losses without reducing the performance. The sole problem from TCP/NC is that TCP/NC sends redundant traffic every pre-set interval which does not recover random losses in time. We suggest an end-to-end adaptive redundancy control based on re-designing the coding scheme from TCP/NC, called Dynamic Coding (DynCod). Our main idea is how the destination can inform to the source whether the latest data sent from the source is decodable or not and how many packet losses occur via acknowledgement packets. Particularly, we change the principle of the information delivered by TCP ACKs: the destination does not only acknowledge every degree of freedom, but also announces how many unseen packets (> 0) remain in the coding window. The source can be informed via TCP ACKs and adjust the number of redundant packets accordingly. We have compared the performances of DynCod and TCP/NC using NS-2. The simulation results show that DynCod outperforms the original TCP/NC in terms of throughput and packet delivery time.

Nowadays, the rapid growth of Cloud computing services is stressing the network communication infrastructure in terms of resiliency and programmability. This evolution reveals missing blocks of the current Internet Protocol architecture, in particular in terms of virtual machine mobility management for addressing and locator-identifier mapping. In this paper, we propose some changes to the Locator/Identifier Separation Protocol (LISP) to cope with this gap. We define novel control-plane functions and evaluate them exhaustively in the worldwide public LISP testbed, involving five LISP sites distant from a few hundred kilometers to many thousands kilometers. Our results show that we can guarantee service downtime upon live virtual machine migration lower than a second across American, Asian and European LISP sites, and down to 300 ms within Europe, outperforming standard LISP and legacy triangular routing approaches in terms of service downtime, as a function of datacenter-datacenter and client-datacenter distances.

Today's mobile terminals have several access network interfaces. New protocols have been proposed during the last few years to enable the concurrent use of multiple access paths for data transmission. In practice, the use of different access technologies is subject to different interconnection costs, and mobile users have preferences on interfaces jointly depending on performance and cost factors. There is therefore an interest in defining “light” multipath communication policies that are less expensive than greedy unconstrained ones such as with basic multipath TCP (MP-TCP) and that are strategically acceptable assuming a selfish endpoint behavior. With this goal, we analyze the performance-cost trade-off of multi-homed end-to-end communications from a strategic standpoint. We model the communication between multi-homed terminals as a specific non-cooperative game to achieve performance-cost decision frontiers. The resulting potential game always allows selecting multiple equilibria, leading to a strategic load-balancing distribution over the available interfaces, possibly constraining their use with respect to basic MP-TCP. By simulation of a realistic three-interface scenario, we show how the achievable performance is bound by the interconnection cost; we show that we can halve the interconnection cost with respect to basic (greedy) MP-TCP while offering double throughputs with respect to single-path TCP. Moreover, we evaluate the compromise between keeping or relaxing strategic constraints in a coordinated MP-TCP context.

Virtualization is a key technology to enable cloud computing. It enhances resource availability and offers high flexibility and cost effectiveness. However, the driver domain-based model for network I/O virtualization exhibit poor networking performance. In this paper, we evaluate the networking performance of VMs based on Xen. The I/O channel transferring packets between the driver domain and the VMs is shown to be the bottleneck. To overcome this limitation, we proposed a packet aggregation-based mechanism to transfer packets from the driver domain to the VM. Experimental performance evaluation showed that our proposal allows the VMs throughput to scale up at line rates. Furthermore, we studied the impact of the aggregation on the packets delay. For this purpose, we proposed a system modeling based on queuing theory. The proposed model allowed us to dynamically tune the aggregation mechanism to achieve the best tradeoff between the packets delay and throughput. The proposed I/O virtualization model henceforth satisfies the infrastructure providers to offer cloud computing services.

The last few years have witnessed an increase in energy consumption in Information and Communication Technology (ICT). Naturally, energy efficient solutions are becoming crucial for both local and wireless access networks. In this paper, we propose a new framework to support energy efficient management in Wireless Mesh Networks (WMNs). A key distinguishing feature of our solution is its online flow-based routing approach since existing flows are dynamically consolidated or even re-routed at fixed intervals according to live arrival and departure of mesh clients. The proposed solution is compliant with emerging Software Defined Networking (SDN) paradigm since it relies on a central controller to monitor and manage the network. To achieve this, we first formulate the problem as an integer linear program (ILP). As this problem is known to be NP-hard, we then propose a simple yet efficient Ant Colony-based approach to solve the formulated ILP problem. Through extensive simulations, we show that our proposed approach is able to achieve significant gains in terms of energy consumption, compared to conventional routing solutions such as the Shortest Path (SP) routing, the Minimum link Residual Capacity routing metric (MRC) and the load balancing (LB) scheme. Specifically, we show that our approach reduces the energy consumption by up to 13%, 20%, and 52%, compared to MRC, SP and LB, respectively, while achieving the required QoS.

Cloud Computing offers elasticity and enhances resource utilisation. This is why its success strongly depends on the efficiency of the physical resource management. This paper deals with dynamic resource reconfiguration to achieve high resource utilisation and to increase Cloud providers income. We propose a new adaptive virtual network resource reconfiguration strategy named VNR-GA to handle dynamic users' needs and to adapt virtual resource allocation according to the applications' requirements. The proposed algorithm VNR-GA is based on Genetic metaheuristic and takes advantage of resources migration techniques to recompute the resource allocation of instantiated virtual networks. In order to optimally adapt the resource allocation according to customers' needs growth, the main idea behind the proposal is to sequentially generate populations of reconfiguration solutions that minimise both the migration and mapping cost and then select the best reconfiguration solution. VNR-GA is validated by extensive simulations and compared to the most prominent related strategy found in literature (i.e., SecondNet). The results obtained show that VNR-GA reduces the rejection rate of i) virtual networks and ii) resource upgrade requests and thus enhances Cloud Provider revenue and customer satisfaction. Moreover, reconfiguration cost is minimised since our proposal reduces both the amount of migrated resources and their new mapping cost.

In this paper, we study the wireless sensor network deployment for water pollution monitoring in the Amazon rainforest rivers. Our objective consists in minimising the number of deployed geographical field installations along the river, while ensuring the detection of the substance spilled in the given river regardless of the position of its source. A geographical field installation is formed by a set of barrier coverage underwater sensors which detect the pollutant if its molarity in the water is greater than a predefined threshold. Indeed, the substance molarity is inversely proportional to the moving distance. To generate the best topology, we propose a sub-optimal novel geographic Installation Field Deployment Algorithm based on the Backtracking heuristic named BT-FIDA. Since the river has a several forks, in order to reduce the number of installation fields, BT-FIDA minimises the rate of at least 2-covered river segments. The simulation results obtained show that our proposal minimises the number of field installations (i.e., deployment cost) while minimising the rate of areas which are miss-covered and over-covered.

Femtocell provisioning is emerging as a key technology to improve coverage and network capacity in indoor environments. When femtocells use different frequency bands than macrocells (i.e., split-spectrum approach), femto-to-femto interference remains the major issue. In particular, congestion cases in which femtocell demands exceed the available resources pose an important challenge. In this paper, we propose a joint resource and power allocation strategy for the management of interference in cooperative femtocell networks. We model the resource and power allocation problem as an operations research game, where imputations are deduced from cooperative game theory, namely the Shapley value and the Nucleolus, using utility components results of partial optimizations. The performance of the developed solutions is analyzed and extensive simulation results are presented to illustrate their potential advantages. In particular, we show that the Shapley value solution with power control offers the overall best performance in terms of throughput, fairness, and transmit power, compared to alternative solutions.

Cloud networking imposes new requirements in terms of connection resiliency and throughput among virtual machines, hypervisors and users. A promising direction is to resort to multipath communications, yet existing protocols still struggle to take advantage of the path diversity offered by IP networks. Multipath TCP (MPTCP) can create several TCP subflows on different interfaces and concurrently forward data on these subflows. Current MPTCP implementations create a full mesh of subflows between IP endhosts, which may be suboptimal according to the topology. We propose to rely on topology information brought by an external protocol in order to improve the MPTCP subflow management; we resort to the Locator/Identifier Separation Protocol (LISP) to retrieve IP path diversity information, to then accordingly create MPTCP subflows. We report noticeable benefits obtained using a large-scale Cloud access test bed, and we describe further work we are conducting in this sense.

In Vehicular Ad-hoc Networks (VANETs), node authentication is an inherent problem since nodes enter and leave the network freely. In wireless networks, the management of identities becomes important because of the propagation medium, where problems such as the loss of node's privacy, the disclosure of personal information, and particularly identity theft and impersonation should be avoided. This paper proposes a pseudonym-based identification scheme that assures security and revocation of identities protecting identity data through advanced cryptography. The presented scheme is based on the generation of a pseudonym formed by node's real identity and an identifier assigned by a trusted third party (Identity Management Server, IMS) after an identification process. The IMS helps to achieve the privacy desired by nodes and the traceability required by law enforcement.

Nowadays, the huge worldwide mobile-phone penetration is increasingly turning the mobile network into a gigantic ubiquitous sensing platform, enabling large-scale analysis and applications. In recent years, mobile data-based research reaches important conclusions about various aspects of human mobility patterns and trajectories. But how accurately do these conclusions reflect the reality? In order to evaluate the difference between the reality and the approximation methods, we study in this paper the error between real human trajectory and the one obtained through mobile phone data using different interpolation methods (linear, cubic, nearest and spline interpolations) while taking into account some mobility parameters. From extensive evaluations based on real cellular network activity data of the Boston metropolitan area, we show that the linear interpolation offers the best estimation for sedentary people and the cubic one for commuters. Moreover, the nearest interpolation appears as the best one for “ordinary people” doing regular stops and standard displacements. Another important experimental finding described in this paper is that trajectory estimation methods show different error regimes whether used within or outside the “territory” of the user defined by the radius of gyration.

Recent research shows that random linear network coding is adapted into current network systems to provide transmission reliability. In lossy environments, like wireless networks, a redundancy control is also needed to mitigate losses. Some implementations suggest adding a fixed amount of redundant packets per batch. This solution poses the risk of wasting bandwidth by over-redundancy or unsuccessful decoding due to packet insufficiency, dramatically degrading the performance. In this paper, we present the Adaptive Redundancy Control for Network Coding (ARC) that adds redundant packets dynamically to mitigate losses. First, ARC is based on the use of MAC acknowledgements as a feedback on the state of link quality. Second, instead of determining the correct number of redundant packets, we decide to find the suitable time to send the redundant packets to cover losses. We design the multi-batch coding scheme that continuously streams new packets while interpreting the received MAC acknowledgements as the feedback on the state of link quality. The state of link quality will be rechecked before every transmission to deduct if it is appropriate for pumping the redundant packets or transmitting the new data. We implemented and compared ARC with 802.11 and FRC - Fixed Redundancy Control in NS-2. Results show that ARC outperforms 802.11 and FRC.

In the last few years, femtocells have gained a great deal of interest as an emerging wireless and mobile access technology to improve indoor coverage and network capacity. In such an environment, mobility management is one of the major concerns that may limit the wide deployment and adoption of such networks. In this paper, we investigate the handover procedure for the two-tier macro/femto LTE networks. An optimized handover algorithm with an efficient call admission control has been proposed and described. Our proposed scheme is mainly designed to reduce the number of unnecessary handovers and to maintain the communication quality during the handover. The choice of the femtocell target takes into account the direction of the mobile user, its velocity and the quality of the signal. Performance evaluation results show that our algorithm minimizes both the number of hand-in and the handover drop rate. Besides, the signal quality in terms of SINR after the hand-in is maintained higher than a fixed threshold, which maximizes the sojourn time of the mobile user within the selected femtocell.

Cloud computing promises to provide on-demand computing, storage, and networking resources. However, most cloud providers simply offer virtual machines (VMs) without bandwidth and delay guarantees, which may hurt the performance of the deployed services. Recently, some proposals suggested remediating such limitation by offering virtual data centers (VDCs) instead of VMs only. However, they have only considered the case where VDCs are embedded within a single data center. In practice, infrastructure providers should have the ability to provision requested VDCs across their distributed infrastructure to achieve multiple goals including revenue maximization, operational costs reduction, energy efficiency, and green IT, or to simply satisfy geographic location constraints of the VDCs. In this paper, we propose Greenhead, a holistic resource management framework for embedding VDCs across geographically distributed data centers connected through a backbone network. The goal of Greenhead is to maximize the cloud provider's revenue while ensuring that the infrastructure is as environment-friendly as possible. To evaluate the effectiveness of our proposal, we conducted extensive simulations of four data centers connected through the NSFNet topology. Results show that Greenhead improves requests' acceptance ratio and revenue by up to 40 percent while ensuring high usage of renewable energy and minimal carbon footprint.

Wireless mesh networks (WMNs) are emerging as a key solution to provide broadband and mobile wireless connectivity in a flexible and cost-effective way. In suburban areas, a common deployment model relies on orthogonal frequency division multiple access (OFDMA) communications between mesh routers (MRs), with one MR installed at each user premises. In this paper, we investigate a possible user cooperation path to implement strategic resource allocation in OFDMA WMNs, under the assumption that users want to control their interconnections. In this case, a novel strategic situation appears: How much an MR can demand, how much it can obtain, and how this shall depend on the interference with its neighbors. Strategic interference management and resource allocation mechanisms are needed to avoid performance degradation during congestion cases between MRs. In this paper, we model the problem as a bankruptcy game taking into account the interference between MRs. We identify possible solutions from cooperative game theory, namely the Shapley value and the nucleolus, and show through extensive simulations of realistic scenarios that they outperform two state-of-the-art OFDMA allocation schemes, namely, centralized-dynamic frequency planning, and frequency-ALOHA. In particular, the nucleolus solution offers best performance overall in terms of throughput and fairness, at a lower time complexity.

With the massive deployment of sophisticated personal devices equipped with different access technologies for both wireless and cellular, mobile users should benefit from service continuity anytime anywhere. This paper seeks to bring seamless connectivity and performance continuity to the mobile users according to their needs and preferences. To this end, it focuses on handover decision that determines the need to initiate the handover and select the best access network. Handover decision in heteregeneous environments is a typical multi-objectives decision issue that requires efficient decision strategies. In this article, we propose an innovative handover decision scheme based on utility theory principles to deal effectively with the challenges revealed by the dynamic, probabilistic, and technological aspects of the multi-objectives decision problem. Our model is based on a single-criterion utility function that rates user satisfaction and captures sensitivity for each decision criterion. As well, an adaptive multi-criteria utility function is defined according to user preferences. Performance of the proposed handover decision strategy is evaluated via extensive simulation studies. Obtained results show that our strategy outperforms other handover decision schemes, which confirm the suitability and the efficiency of our solution.

Nowadays, wireless networks with heterogeneous technologies are largely deployed and, mobile terminals have multiple interfaces to access these networks. This raises many research issues such as the simultaneous access to heterogeneous networks and the mobility management. This paper proposes to manage the mobility of a terminal in this context. In particular, we want to guarantee that, while a terminal is moving from a given network to a different one, the quality of service of its applications will be maintained. For this purpose, we combine a multi-homing protocol (SHIM6) with an IMS architecture. The protocol SHIM6 ensures a seamless change of networks without any application disruption. The IMS architecture allows the establishment of multimedia session with quality of service. Our solution can manage the inter-domain mobility of a terminal in a reactive and proactive mode. For this purpose, we implement a SIP proxy inside the mobile terminal. The experimental evaluation shows the feasibility of the SHIM6-IMS integration and a considerable reduction of the handover delay.

Cloud computing is an emergent paradigm that allows to customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose to integrate an SLA-based Dynamic Bandwidth Allocator (DBA) in a virtualized cloud environment. DBA manages bandwidth allocation efficiently through allocating bandwidth according to the application requirements and the established agreement. It also adjusts the allocated bandwidth dynamically upon change and reduces physical resources usage by dropping packets in the virtual machines rather than the driver domain. Through experimental evaluation we showed the efficacy of the proposed algorithm and the agreements respect.

The context of our work is mobile multi-homed terminals in a heterogeneous environment. We propose a solution for seamless terminal mobility in an intra-domain context. We combine a multi-homing protocol (SHIM6), which ensures seamless network change, with the IMS architecture, which allows the establishment of multimedia session with Quality of Service. Our proposal allows a mobile terminal to change its access network seamlessly, without any application disruption. To achieve this, we implement a Proxy-SIP inside the terminal to manage session establishment. The proposed scheme can manage access network change in two modes: reactive and proactive. A testbed allowed us to show the feasibility of our approach and the gain obtained by considerably reducing the handover delay and, thus, data loss.

In this paper, we propose a new dynamic adaptive virtual network resource allocation strategy named Adaptive-VNE to deal with the complexity and the inefficiency of resource allocation. The proposal coordinates virtual node and virtual link mapping stages. The main idea behind the proposal is take advantage of unused bandwidth with respect to the occupancy rate of embedded virtual links. Hence, the unused bandwidth will be reassigned to incoming virtual network requests. To do so, Adaptive-VNE adopts the “divide and conquer” strategy. It divides the virtual network request topology into many star topologies. Then, the mapping of each piece within the whole topology is formulated as a K-supplier problem and resolved by an approximation bottleneck algorithm. To generate the global virtual network topology, Adaptive-VNE uses a backtracking algorithm in order to minimise the global mapping cost. Note that the proposal forecasts usage rate of virtual links and adapts their bandwidth reservation. Adaptive-VNE was validated by simulations and compared to the related strategies found in literature. The results obtained show that, contrarily to static bandwidth allocation approaches, the adaptive strategy maximises substrate bandwidth usage while the virtual links' bottleneck rate is minimised. Moreover, the congestion periods are minimised and during the bottleneck the bandwidth satisfaction is maximised. Finally, Adaptive-VNE improves performances in terms of acceptance rate of virtual networks and revenue of infrastructure providers.

This paper proposes a new joint power control and resource allocation algorithm in OFDMA femtocell networks. We consider both QoS constrained high-priority (HP) and best-effort (BE) users having different types of application and bandwidth requirements. Our objective is to minimize the transmit power of each femtocell, while satisfying a maximum number of HP users and serving BE users as well as possible. This optimization problem is multi-objective NP-hard. Hence, we propose a new scheme based on clustering and taking into account QoS requirements of users. We show by extensive network simulation results that our proposal outperforms three state of the art schemes (Centralized-Dynamic Frequency Planning, C-DFP, Distributed Random Access, DRA and Distributed Resource Allocation with Power Minimization, DRAPM as well as our previous proposal, FCRA, in both low and high density networks. The results concern the rate of rejected users, the throughput satisfaction rate, the spectrum spatial reuse, fairness, as well as computation time.

Femtocells have recently appeared as a viable solution to enable broadband connectivity in mobile cellular networks. Instead of redimensioning macrocells at the base station level, the modular installation of short-range access points can grant multiple benefits, provided that interference is efficiently managed. In the case where femtocells use different frequency bands than macrocells (i.e., split-spectrum approach), interference between femtocells is the major issue. In particular, congestion cases in which femtocell demands exceed the available bandwidth pose an important challenge. If, as expected, the femtocell service is going to be separately billed by legacy wire-line Internet Service Providers, strategic interference management and resource allocation mechanisms are needed to avoid performance degradation during congestion cases. In this paper, we model the resource allocation in cooperative femtocell networks as a bankruptcy game. We identify possible solutions from cooperative game theory, namely the Shapley value and the Nucleolus, and show through extensive simulations of realistic scenarios that they outperform two state-of-the-art schemes, namely Centralized-Dynamic Frequency Planning, C-DFP, and Frequency-ALOHA, F-ALOHA. In particular, the Nucleolus solution offers best performance overall in terms of throughput and fairness, at a lower time complexity.

Recently, operators have resorted to femtocell networks in order to enhance indoor coverage and increase system capacity. Nevertheless, to successfully deploy such solution, efficient resource allocation algorithms and interference mitigation techniques should be deployed. The new applications delivered by operators require large amounts of network bandwidth. Whereas, some customers may want to pay more in exchange for a better quality of service (QoS), some others need less resources and can be charged accordingly. Hence, we consider an OFDMA femtocell network serving both QoS constrained high-priority (HP) and best-effort (BE) users. Our objective is to satisfy a maximum number of HP users while serving BE users as well as possible. This optimization problem is multi-objective NP-hard. For this aim, we propose in this paper a new resource allocation and admission control algorithm, called Q-FCRA, based on clustering and taking into account QoS requirements. We show by extensive network simulation results that our proposal outperforms two state of the art schemes (Centralized-Dynamic Frequency Planning, C-DFP, and Distributed Random Access, DRA) as well as our previous proposal, FCRA, in both low and high density networks. The results concern the number of accepted users, the fairness, the throughput satisfaction rate and the spectrum spatial reuse.

Wireless Mesh Networks (WMNs) are emerging as a key solution to provide broadband and mobile wireless connectivity in a flexible and cost effective way. In suburban areas, a common deployment model relies on OFDMA communications between mesh routers (MRs), with one MR installed at each user premises. In this paper, we investigate a possible user cooperation path to implement strategic resource allocation in OFDMA WMNs, under the assumption that users want to control their interconnection. In this case, a novel strategic situation appears: how much a MR can demand, how much it can obtain and how this shall depend on the interference with its neighbors. Strategic interference management and resource allocation mechanisms are needed to avoid performance degradation during congestion cases between MRs. In this paper, we model the problem as a bankruptcy game taking into account the interference between MRs. We identify possible solutions from cooperative game theory, namely the Shapley value and the Nucleolus, and show that they outperform two state-of-the-art schemes, namely Centralized-Dynamic Frequency Planning, C-DFP, and Frequency-ALOHA, F-ALOHA. In particular, the Nucleolus solution offers best performance overall in terms of throughput and fairness.

Today's mobile terminals have several access network interfaces. In practice, the use of different access technologies is subject to different interconnection costs, and mobile users have preferences on interfaces jointly depending on performance and cost factors. There is therefore an interest in defining “light” yet rational multipath communication policies less expensive than greedy ones such as with basic Multipath TCP (MP-TCP). We analyze the performance-cost trade-off of multi-homed end-to-end communications from a strategic standpoint. We model the communication between multi-homed terminals as a multi-criteria non-cooperative game so as to achieve performance-cost decision frontiers. The resulting potential game always allows to select multiple equilibria, which correspond to a strategic load-balancing distribution over the available interfaces, possibly constraining their use with respect to basic MP-TCP. We specify how the resulting model may be in practice implemented by users willing to jointly control the interconnection cost and the performance, based on user Quality of Experience (QoE) assessments. By simulation of a realistic 3-interface scenario, we show how the achievable performance is bound by the interconnection cost; we show that we can halve the interconnection cost with respect to basic (greedy) MP-TCP under a reasonable trade-off, while offering double throughputs with respect to single-path TCP.

In wireless mesh networks, network coding can be adapted and deployed for performance enhancement. Some early results such as COPE, BEND and DCAR show that the use of network coding can outperform the original 802.11 networks. However, these network coding architectures have two limitations: (i) the coding chances inevitably depend on the established route, (ii) traffic is strictly coded based on the two-hop coding pattern. In this paper, a novel and enhanced network coding architecture, Distributed Opportunistic Diffused Encoding (DODE), is proposed. DODE combines (i) the diffused gain from BEND and (ii) the generalized coding condition from DCAR to completely solve the limitations present in the three previous propositions. In addition, we propose a routing metric called Shortest Path with Enriched Neighborhood routing Metric (SPENM) which allows DODE to follow the most enriched coding chance path and also to enjoy the diffused gain. We implement DODE system in NS-2. The simulation results show that DODE outperforms 802.11, COPE, BEND and DCAR.

Cloud computing is an emergent paradigm that allows customers to rent infrastructure, platforms and software as a service. With resource sharing and reuse through virtualization technology, cloud environments become even more cost effective and flexible. Nevertheless, networking within virtualized cloud still presents some challenges in performance and resource allocation. In this paper, we propose DBA-VM, a Dynamic Bandwidth Allocator for Virtual Machines with regard to the established SLAs. The proposed scheme enforces the isolation between the virtual machines through the transmission bandwidth adjustment at the network I/O channel. The experimental performance evaluation shows that DBA-VM allows to the virtualized system to respect each virtual machine SLA while reducing the global physical resources (CPU and memory) consumption.

Technology advances and services of modern networks have noticeably complicated their management such that in the near future it will be almost unfeasible for human administrators to monitor them. To manage this complexity, IBM has proposed the autonomic paradigm with its four self-management properties. Autonomic computing/networking intends to design computing architecture capable to self-adapt its configuration and to self-optimize its performance depending on its state in order to fulfil high-level goals predefined by the human operator. In this research work, we introduce AutoXL, a cross-layer autonomic architecture. AutoXL adopts a Knowledge plane and a Policy plane. The Knowledge plane is responsible of the management of knowledge (local and network-wide) which enables an autonomic element to be self-aware of its environment. The Policy plane is responsible of managing policies guiding the autonomic element to achieve the predefined objectives. Furthermore, we propose guidelines for autonomic architectures evaluation.

In Cognitive Radio Networks (CRN), the appearance of more active primary users (PUs) might require blocking of one or more secondary user (SU) transmissions to maintain interference constraints at PU receivers and Quality of Service (QoS) constraints of SUs. In general, SU transmitters need to adjust their transmission powers to maintain these constraints at all times. In this paper, we are interested in maximizing the number of concurrent SU flows under new PU arrivals and performing power allocation for SU links belonging to maintained data flows to maximize the minimum flow capacity. In particular, we develop a flow maintenance and power control scheme to solve this problem, which is referred to as Flow-Based Power Control (FBPC). The proposed scheme comprises two phases where we attempt to find a best set of flows with maximum size in the first phase and maximize the minimum flow capacity through power control in the second phase. To reduce computation complexity required in the first phase, we develop a flow combination metric, which is used to find the best flow combination. Moreover, we formulate power allocation problem that maximizes the minimum flow capacity and show how to transform it into a geometric convex program. Numerical results are presented to show the efficiency of the proposed flow combination metric and the desirable performance of the proposed two-phase flow maintenance and power control scheme.

Sky computing is a promising concept enabling a flexible deployment of geographical distributed applications. Whereas, it is faced with a fundamental challenge which is: “efficient resource utilisation” within Cloud's infrastructure. Hence, a high flexible and intelligent resource allocation scheme is necessary to accommodate unpredictable and variable users demands. This paper tackles the fundamental challenge of efficient resource allocation within Cloud's backbone network. The ultimate goal is to satisfy the Cloud's user requirements while maximising Cloud provider's revenue. The problem consists in embedding virtual networks within substrate infrastructure. A new dynamic adaptive virtual network resource allocation strategy named Backtracking-VNE is investigated to deal with the complexity of resource provisioning within Cloud network. The proposal coordinates virtual nodes and virtual links mapping stages to optimise resources usage. Moreover, thanks to forecasting module, Backtracking-VNE guarantees an efficient resources share between embedded virtual links with respect to their occupancy. We demonstrate through extensive simulations that contrarily to static bandwidth allocation approaches, Backtracking-VNE enhances substrate bandwidth usage whilst minimising virtual links congestion. Acceptance rate of virtual networks and Cloud providers income are also improved compared with related strategies.

In wireless mesh networks for unicast traffic, opportunistic network coding are specifically introduced for improved network utilization. Some recent practical implementations like COPE, BEND, DCAR and DODE have shown the promising results over the original 802.11 conventional forwarding mechanism. For better performance, the aim of all mentioned network coding implementations is trying to find more and more coding chances in network topologies. However, they restricted the finding within a simple rule "a pair of coder and decoder". For every coded packet (the combination of natives packets of traffic flows) sent on the traffic flow, we always have one coder (which creates the coded packet) and one decoder (which retrieves the desired packet for the destination). The trivial rule limited coding chances much. In this paper, we are loosing this noose: we decouple the coding and decoding functions from strictly a pair of coder and decoder. For one coder, we can have multiple decoders on the path (up to the number of other traffic flows involved in the coding). With this, more coding chances are found, thus, improving the network performance. We extend our proposed DODE with this new idea, called Distributed Opportunistic and Diffused Coding with Multiple Decoders - DODEX. We implement DODEX system in NS-2. The simulation results show that DODEX can outperform its previous introducing systems.

An important design goal for wireless local area networks (WLANs) is the performance. It is well known that the major issue challenge to the performance in WLANs is the wireless interference. This leads to an ambience that depends on the channel assignments among interfering access points (AP). Due to the limited number of non-overlapping channels, severe interference scenarios may arise if an unappropriate spectrum planning is considered. In our study we considered WLANs scenarios where APs belong to different administrative domains, a common situation in dense urban deployments. In such environment the use of centralized algorithms is not appropriate and the already proposed distributed methods do no guarantee optimal channel assignment. In this paper, we formalize the channel allocation as a distributed constraint optimization problem (DCOP) and propose a new cooperative channel allocation strategy using the distributed pseudo tree-optimization procedure (DPOP). The adjacent channel interference is analytically formulated for DPOP. The simulation results show that the proposed strategy always achieves the optimal solution and is scalable in terms of the number of exchanged messages.

The performance of a wireless local area network depends on the channel assignments among neighboring access points (APs). The limited number of non-overlapping channels may lead to severe interference scenarios if no appropriated spectrum planning is employed. Additionally, in dense urban areas it is usual to find wireless networks scenarios with interfering APs belonging to different administrative domains. In such cases the use of centralized algorithms is not feasible and the already proposed distributed methods do not guarantee optimal channel assignment. In this paper, we formalize the channel allocation as a distributed constraint optimization problem and propose a new cooperative channel allocation strategy using the distributed pseudotree-optimization procedure (DPOP). The adjacent channel interference is analytically formulated for DPOP. The simulation results show that the proposed strategy always achieves the optimal solution and is scalable in terms of the number of exchanged messages.

An important characteristic in trust management frameworks is how nodes obtain information about the trustworthiness of other nodes. Some trust management models are based on local information, while others use both information of neighbors and remote nodes. Despite the wide of information used, the existing trust monitoring approaches are mainly based either on passive monitoring mechanisms or on active monitoring mechanisms. While passive monitoring suffers from limitations ranging from strict antenna requirements to high battery use, active dissemination alternatives generate extra overhead to the resource constrained mobile ad hoc networks (MANETs). In this paper, we propose a new knowledge monitoring scheme for trust management on MANETs based on autonomic principles. The proposed scheme minimizes the overhead using transiting packets on the network to update nodes knowledge about other nodes trustworthiness. Simulation results show that the proposed mechanism improves significantly the performance of underlying network, providing a sufficient correct knowledge about nodes trustworthiness required by trust management frameworks.

Due to the raising dependence of people on critical applications and wireless networks, high level of reliability, security and availability is claimed to assure secure and reliable service operation. Wireless ad hoc networks (WANETs) experience serious security issues even when solutions employ preventive or reactive security mechanisms. In order to support both network operations and security requirements of critical applications, we present SAMNAR, a Survivable Ad hoc and Mesh Network ARchitecture. Its goal lies in managing adaptively preventive, reactive and tolerant security mechanisms to provide essential services even under attacks, intrusions or failures. We use SAMNAR to design a path selection scheme for WANET routing. The evaluation of this path selection scheme considers scenarios using urban mesh network mobility with urban propagation models, and also random way point mobility with two-ray ground propagation models. Results show the survivability achieved on routing service under different conditions and attacks.

In this paper we address the problem of virtual network reconfiguration. In our previous work on virtual network embedding strategies, we found that most virtual network rejections were caused by bottlenecked substrate links while peak resource use is equal to 18%. These observations lead us to propose a new greedy Virtual Network Reconfiguration algorithm, VNR. The main aim of our proposal is to 'tidy up' substrate network in order to minimise the number of overloaded substrate links, while also reducing the cost of reconfiguration. We compare our proposal with the related reconfiguration strategy VNA-Periodic, both of them are incorporated in the best existing embedding strategies VNE-AC and VNE-Greedy in terms of rejection rate. The results obtained show that VNR outperforms VNA-Periodic. Indeed, our research shows that the performances of VNR do not depend on the virtual network embedding strategy. Moreover, VNR minimises the rejection rate of virtual network requests by at least ≃83% while the cost of reconfiguration is lower than with VNA-Periodic.

Network virtualization is a promising technology that offers high levels of flexibility, isolation, extensibility and cost-effectiveness. In this paper, we focus on router virtualization. We evaluate the forwarding performance of virtual routers when the data plane runs in the guests. This scenario offers a high level of isolation and flexibility, however, it suffers from performance limitations due to the virtualization overhead. We show that the he I/O communication between the driver domain and the guests is the bottleneck. To overcome this limitation, we propose a new packets aggregation mechanism that transfers groups of packets between the driver domain and the guests. This enhancement makes the forwarding performance of one guest scale up to 1600 Kp/s. Furthermore, we propose a dimensioning tool in order to determine the maximum achievable throughput with regard to the container size.

In this paper, we address a virtual network embedding problem. Indeed, our objective is to map virtual networks in the substrate network with minimum physical resources while satisfying its required QoS in terms of bandwidth, power processing and memory. In doing so, we minimize the reject rate of requests and maximize returns for the substrate network provider. Since the problem is NP-hard and to deal with its computational hardness, we propound a new scalable embedding strategy named \texttt{VNE-AC} based on the Ant Colony metaheuristic. The intensive simulations and evaluation results show that our proposal enhances the substrate provider's revenue and outperforms the related strategies found in current literature.

Recently, operators have resorted to femtocell networks in order to enhance indoor coverage and quality of service since macro-antennas fail to reach these objectives. Nevertheless, they are confronted to many challenges to make a success of femtocells deployment. In this paper, we address the issue of resources allocation in femtocell networks using OFDMA technology (e.g., WiMAX, LTE). Specifically, we propose a hybrid centralized/distributed resource allocation strategy namely Femtocell Cluster-based Resource Allocation (FCRA). Firstly, FCRA builds disjoint femtocell clusters. Then, within a cluster the optimal resource allocation for each femtocell is performed by its cluster-head. Finally, the contingent collisions among different clusters are fixed. To achieve this, we formulate the problem mathematically as Min-Max optimization problem. Performance analysis shows that FCRA converges to the optimal solution in small-sized networks and outperforms two prominent related schemes (C-DFP and DRA) in large-sized ones. The results concern the throughput satisfaction rate, the spectrum spatial reuse, and the convergence time metrics.

The extreme dynamics of wireless multi-hop networks (WMN) - those that use multiple wireless links to forward data - require self-configuration solutions in every communication layer. Self-configuration demands mechanisms for information sharing, as well as specific decision-making algorithms for each service or application. Self-configuration must also be embedded in the communication layers in order to cope with changes in the wireless environment. This article is a digest of the three contributions of, which investigated the self-configuration tasks of programmability, sharing of information and specialized control loops for WMN. First, we designed a middleware, based on the Information Plane (InP) concept, to ease the programmability and sharing of information among nodes. Next, we proposed two InP-based control loops for WMN: one for data rate and transmission power aware routing, and another for mobile context-aware peer-to-peer services.

Router virtualization seems as the obvious next step to system virtualization and the key to easily deploy and manage next generation overlay virtual networks. In this paper, we investigate the viability of virtual routers on a Xen-based system. We first evaluate the system throughput when achieving forwarding in the virtual routers. Then, we consider the context where virtual routers are dedicated to flows of different types and propose a mechanism to guarantee the required throughput and latency to real time applications while maintaining an optimal aggregated system throughput. We achieved this through both configuring the Xen Credit scheduler and establishing priorities between packets in the driver domain before switching them to the target virtual router.

Virtual routers on commodity hardware are an attractive solution for service providers that look for extensibility, flexibility, reuse and low deployment cost. However, these routers still suffer from performance limitations due to the virtualization overhead and the commodity hardware architecture itself. In this paper, we first evaluate the baseline forwarding performance of virtual routers based on a Xen environment. Then, we show that the memory latency is the bottleneck. Hence, we propose a Fast Bridge that demultiplexes incoming packets and then transfers them to the destined guest machines. It constructs packets containers in the driver domain, based on their destination and their delay constraints. Then it transfers them as a unit to the guests. This allows transferring more packets and fastest memory access and results in a much better throughput with an acceptable guaranteed delay.

In this paper, we address the radio resource utilization efficiency in single channel wireless mesh networks (WMNs) while considering the mobility of users and when multiple simultaneous connections on the same channel exist in the network. To achieve this, we use clustering. We first identify through analytical models and simulations the cases where clustering is helpful. Building on these results, we propose two clustering schemes that take into consideration the mobility properties of users in order to improve the WMN performance. We prove that both schemes can achieve significant gains in terms of radio resource utilization, especially when the number of simultaneous connections in the network increases. Specifically, we show that the first scheme fits better low-connected wireless mesh networks, whereas the second scheme is more suitable for highly-connected networks.

In this paper, we will address a WSN deployment problem. The main objectives are i) reduce the cost of deployment, ii) ensure the requested event detection probabilities, iii) guarantee the network connectivity, and iv) maximize the lifetime of the network. We will formalize the problem as multi-objective combinatorial optimization problem. To resolve the problem, we will propose a new deployment algorithm named MODA. It will be based on evolutionary and neighborhood search algorithms. The obtained results are better than the deployment strategies found in the literature.

This paper presents a new metric for routing in wireless mesh networks (WMNs). The proposed metric does not only consider the quality of wireless links to choose a high throughput path between a pair of nodes, but it also includes the resulting interference introduced by using such links. The philosophy behind this metric is to choose a good path for an arriving connection, not necessarily the best in terms of throughput, but that alleviates the resulting interference in order to preserve good paths for the subsequent arriving connections. In doing so, we find that our metric significantly outperforms previously proposed routing metrics when multiple concurrent flows are considered in the network. The total network throughput is indeed increased.

Quality of service (QoS) is a key problem in wireless environments where bandwidth is scarce and channel conditions are time varying and sometimes implies highly packet losses. IEEE 802.11b/g/a wireless LAN (WLAN) are the most widely used WLAN standards today, and the IEEE 802.11e QoS enhancement standard exists and introduces QoS support for multimedia applications. This paper presents a class based admission control algorithm for 802.11e based wireless local area networks. The strengths of our admission control is dynamicity and flexibility of the algorithm, which adapts to the situation of the BSS, like global load, number of best effort AC, and position of QSTA by report of QAP, thing that have never been taken together, but each solutions have used a point of sight separately. Thus it achieves higher throughput than other admission control for 802.11 e. The idea which consists of changing parameters [AIFSN, CWmin and CWmax] of best effort flows, for decreasing collisions, is used, so we think that it is an efficient way to protect QoS flows from best effort flows, and to allow reducing then number of collisions. So we increase AIFSN [best effort flow], CWmin and CWmax only at 70% of load of network, to prevent starvations of best effort flows, and so we increase rate utilization of channel. We also use the current rate transmission of QSTAs, according to their positions, instead of the minimum rate transmission used by standard 802.11e, for calculate the load of network and derived the TXOPi necessary for all the stations, with i=1 to number of active stations. The 802.11e standard starves the low priority traffic in case of high load, and leads to higher collision rates, and did not make a good estimate of weight of queues, so there is an unbalance enters the flows with high priorities. A discussion is presented in detail using simulation-based evaluations, with an aim of comparing results of our admission control algorithm, with the 802.11e standard and the FHCF algorithm. Results reveal an improvement of the network load and a decrease of the number of collisions.

In this paper a new technique called The HandOver Decision STAbility Technique (HODSTAT) is proposed for horizontal handover in Wireless Local Area Networks based on IEEE 802.11 standard. HODSTAT addresses the decision instability which impacts negatively on both user perception and network performances. HODSTAT is based on a hysteresis margin analysis that, combined with a utility-based function, evaluates the need for the handover and determines if the handover is needed or can be avoided. Indeed, if a Mobile Terminal (MT) only transiently hands over to a better network, the gain from using this new network may be diminished by the handover overhead and short usage duration. The approach that we adopt throughout this article aims at reducing with the minimum handover occurrence that leads to network connectivity cut which causes additional delay and packet loss. To this end, MT rather performs a handover only if the connectivity of the current network is threatened or if the performance of a neighboring network is really better comparing to the current one with a hysteresis margin. This hysteresis should make a tradeoff between handover occurrence and the necessity to change the current network of attachment. Through our extensive simulation results, we show that our proposed algorithm outperforms other decision stability approaches for handover decision algorithm.

This paper addresses the issue of wireless resource allocation of a Mobile WiMAX cell based on OFDMA access technique. We compare two strategies: the MAX SNR which is the most used channel assignment technique and our proposal which is based on channel condition learning. As we distinguish four IEEE 802.16e-2005 service classes: UGS, rtPS, nrtPS and ErtPS, we combine these strategies with a scheduler block in order to satisfy the QoS constraints of these classes. In addition, we take into consideration the Adaptive Modulation and Coding (AMC) scheme, through the selection of the slot which is based on the modulation scheme. The main concern here is to propose a simple method to assign WiMAX physical resources called slot to satisfy QoS constraints of a user's scheduled MPDUs, which can be easily and efficiently used in a realistic Mobile WiMAX network.

In this paper, we propose a human-based model which builds a trust relationship between nodes in an ad hoc network. The trust is based on previous individual experiences and on the recommendations of others. We present the Recommendation Exchange Protocol (REP) which allows nodes to exchange recommendations about their neighbors. Our proposal does not require disseminating the trust information over the entire network. Instead, nodes only need to keep and exchange trust information about nodes within the radio range. Without the need for a global trust knowledge, our proposal scales well for large networks while still reducing the number of exchanged messages and therefore the energy consumption. In addition, we mitigate the effect of colluding attacks composed of liars in the network. A key concept we introduce is the relationship maturity, which allows nodes to improve the efficiency of the proposed model for mobile scenarios. We show the correctness of our model in a single-hop network through simulations. We also extend the analysis to mobile multihop networks, showing the benefits of the maturity relationship concept. We evaluate the impact of malicious nodes that send false recommendations to degrade the efficiency of the trust model. At last, we analyze the performance of the REP protocol and show its scalability. We show that our implementation of REP can significantly reduce the number messages.

RFID is an automatic identification technology that enables tracking of people and objects. This research focuses on improving context-awareness by associating locations to identities. We propose L-VIRT, an extension of our 3-D range- free localization method for RFID tags that uses additional mobile readers to refine its accuracy. Topological constraints are deduced from connectivity information and combined with virtual landmarks to localize tags. Mobile tags are localized with the static reader infrastructure while the localization of static tags is enhanced with mobile readers. Simulation results show a fine-grained accuracy when readers are densely deployed and an impressive error reduction when few mobile readers are involved.

This paper presents an autonomic load balancing algorithm (ALBA) which enhances resource allocation in wireless local area networks (WLAN). ALBA offers autonomic management capabilities to access points that ensure the accommodation of more user traffic and an overall network capacity improvement compared to default signal strength based connectivity. Simulations with VoIP traffic over an agglomeration of WLANs show consistent behaviour among neighbouring access points and substantial performance gain in terms of call blocking rate.

The increasing popularity of WLANs-due to the use of license-free radio spectrum with low-cost, easily deployable and high-data-rate wireless services- has encouraged service providers to consider deploying them in high density usage areas, such as public hotspots, to provide complementary broadband access to their networks and services. This article proposes a Session Initiation Protocol based QoS management architecture that aims to provide consistent QoS control for multimedia applications (VoIP, VoD, ...) over wireless access networks. In particular, we will present a generic QoS based management architecture for decentralized management of multimedia applications over wireless access networks, such as WLAN. We will apply our architecture to the management of the WLAN in order to assure QoS (throughput and delay) for the delivered multimedia applications according to users' priorities and providers' objectives. Performance evaluations are discussed to illustrate the feasibility and the efficiency of the proposed architecture through the implementation of a real-world testbed.

This paper addresses the issue of wireless sensor network (WSN) deployment. We investigate this problem in the case where the monitored area is characterized by a geographical irregularity of the sensed events. Precisely, we consider that each point of the deployment area requires a minimum threshold guarantee on the event detection probability. Our proposed scalable deployment method, named potential field-based deployment algorithm (PFDA), is based on the potential field and the virtual force approaches. Our proposal is able to (1) satisfy the required event detection probability threshold for each point, in a large-scale area, while minimizing the number of deployed sensors and (2) to ensure the network connectivity. The results and evaluation analysis show that PFDA outperforms the other strategies proposed in literature.

Cryptographic techniques are at the center of security solutions for wireless ad hoc networks. Public key infrastructures (PKIs) are essential for their efficient operation. However, the fully distributed organization of these networks makes a challenge to design PKIs. Moreover, changes in network paradigms and the increasing dependency on technology require more dependable, survivable and scalable PKIs. This paper presents a survivable PKI whose goal is to preserve key management operations even in face of attacks or intrusions. Our PKI is based on the adaptive cooperation among preventive, reactive and tolerant defense lines. It employs different evidences to prove the liability of users for their keys as well as social relationships for helping public key exchanges. Simulation results show the improvements achieved by our proposal in terms of effectiveness and survivability to different attacks.

ADMA represents an Autonomous Decentralized Management Architecture designed to provide Mobile Ad Hoc Networks (MANETs) with autonomic principles. It allows the network to configure and reconfigure itself under environment changes without any human intervention. Our solution operates in a peer-to-peer manner and does not require any centralized entity to perform network management functions. Each mobile node implementing ADMA components is able to take the appropriate decision based on predefined high level policies and collected monitoring information. We present in this paper the basic components of an ADMA node. Then, we provide a simple self-configuring case study of our design considering Voice over IP (VoIP) as a test application. Simulation results show an improvement of the VoIP delay and loss rate while applying predefined policies.

The provision of Quality of Service (QoS) over wireless networks has recently been the subject of intensive research. There is a growing consensus among the research community that combining cross-layering and autonomic paradigms is, until now, the best alternative for better QoS support in such networks. The cross-layer concept is recommended to over-come the performance problems of the wireless channel, and the autonomic concept is imposed as the size and complexity of networks grow. Most proposed cross-layer architectures lack of autonomicity. Moreover, the majority of them considers purely local information in their optimizations and do not care about the effects of such egoistic behavior on other wireless nodes. This non-collaborative behavior limits the overall system performance. We combine cross-layering and autonomic concepts in the design of a new architecture called XLEngine (Cross-Layer Engine) having the ability to make optimizations based on local and network wide knowledge. We implemented XLEngine under the simulator J-Sim. We show, through simulations, that our XLEngine architecture significantly outperforms the layered architecture.

This paper explores the perceptual effect of network delay jitters on consumers' quality of experience during packet-based VoIP conversations. Novel parametric speech quality models are proposed to faithfully capture speech quality impairment caused by network delay jitter and de-jittering buffer settings. The proposed models have been rigorously conceived following a regression analysis approach using a wide range of network delay jitter traces and de-jittering buffer settings. The network delay traces were synthetically produced by a stochastic generator, widely used by the research community. Moreover, new speech quality models, which quantify the individual and mixed perceptual effect of network random packet losses and delay jitter, are proposed and validated. The packet layer key parameters of proposed speech quality models, namely mean network delay jitter and de-jittering buffer delay, are easily accessible at run-time. Experimental results show that our no-reference speech quality models correlate very well with the standard full-reference speech quality models. Indeed, our performance evaluation shows correlation factors equal to 0.97 and 0.94 for, respectively, the G.711 and the G.729 CODECs. The proposed speech quality models should help design optimized schemes for network delay jitter removal, thus improving the perceptual speech quality for a given network delay jitter intensity. Moreover, the speech quality models can be used to accurately measure in a non-intrusive way the perceptual effect of network delay jitter and packet loss, separately. This constitutes a desirable feature, as it enables the smart mitigation of the sources of speech quality degradation.

Wireless mesh networks are an appropriate solution for broadband home networks in order to establish a ubiquitous environment. One of the main challenges in ubiquitous networks is context-awareness and personalized service discovery. Many service discovery protocols have been proposed in the literature. The most significant is the Universal Plug and Play (UPnP) technology, based on the Simple Service Discovery Protocol (SSDP) and targeted for home network environment. However, the UPnP technology has some drawbacks and particularly does not consider user context. In this paper we present a framework that provides an extension for the UPnP architecture and employs context-aware concepts to achieve service discovery continuity in evolving environments where devices may move inside the home and change their point of attachment within the wireless mesh network. This extension is carefully designed for wireless mesh controllers, and is compatible with the existing UPnP framework. It keeps the process of service discovery as simple and automatic as possible.

One of the main challenges in ubiquitous networks is localization. Many positioning methods have been proposed in the literature since this data is critical for numerous protocols and services. Choosing the right localization algorithm for a specific environment is a hard task. However, it is even more complex when several radio access technologies are available in evolving environments. This paper presents a framework based on autonomic networking concepts to achieve localization in ubiquitous networks. This approach uses ambient intelligence to provide flexibility, accuracy, and energy savings.

IEEE 802.16 standard suite defines two main polling modes, unicast polling and contention-based polling, to support different bandwidth allocation requirement. Although the specification introduces four service classes to adaptively implement the polling mechanisms for different type of traffics, it does not specify exactly how these polling modes could be used for efficient bandwidth allocation. In this paper, we investigate the polling mechanisms in IEEE 802.16 networks, and propose a simple but efficient polling mechanism to optimize the performance. The simulation results show that the proposed polling mechanism can utilize the uplink bandwidth efficiently and achieve better performance.

Due to the emergence of multimedia context-rich applications and services over wireless networks, networking protocols and services are becoming more and more integrated, thus relying on context and application information to support their operation. Further, wireless protocols and services now employ information from several network layers and the environment, breaking the layering paradigm. In order to cope with this increasing reliance on information, we have proposed MANIP, a middleware for MANETs that instantiates a new networking plane. The Information Plane (InP) is a distributed entity to store and disseminate information concerning the network, its services and the environment, orchestrating the collaboration among cross-layer protocols, autonomic management solutions and context-aware services. We use MANIP to support the autonomic reconfiguration of a P2P network over MANETs. Simulation results show that the MANIP-enabled solutions reduce the response time and increase the number of solved P2P queries when compared to classic, cross-layer implementations of the same protocols.

Intelligent and dynamic management is essential for improving WLAN efficiency, especially when multimedia and other QoS demanding applications are employed. In this paper, we propose a Recursive Autonomic Load Balancing Algorithm (RALBA)for WLANs and test its applicability for a VoIP over WLAN (VoWLAN) use case. A load metric is used to identify how many VoIP flows the WLAN cell can support. RALBA uses a Knowledge Plane to obtain high- level information about network state. The algorithm is presented and illustrated along with implementation plans.

Service continuity in heterogeneous wireless access technologies is a main issue. The challenge is to preserve continuous services while moving between these technologies. Making the decision to which network to switch (handoff) is one of the main key. In order to achieve the service continuity, we must rely on seamless vertical handoff techniques with a minimum processing-delay. In this paper we propose a vertical handoff decision scheme to enhance the service mobility using the simple additive weighting (SAW) method in a distributed manner, under heterogeneous environments. Our main goal is to reduce the overload and the processing-delay in the mobile terminal, by delegating the calculation of handoff metrics for network selection to the target visiting networks.

In this article, we focus on the service-driven management of quality of service and user access in wireless corporate networks. We propose a service-level agreement (SLA) oriented nomadism management architecture with a top-down vision starting by the specification of company objectives and going down to device-level configurations. We define an algorithm for the automatic translation of application-level quality assurance parameters into network-level configuration parameters. The description of the prototype implementation of our solution to the SLA-driven enterprise nomadism management is given and preliminary results on the self-adaptive capabilities of our mapping algorithm are given.

In this paper, we address the wireless sensor network (WSN) deployment issue. Compared to similar works, we relax some assumptions that were generally considered in the literature. Precisely, instead of the classical binary detection model, we consider a distance-related probabilistic one. Moreover, we assume that the observed area is characterized by the geographical irregularity of the sensed events. Our resulting differentiated WSN deployment problem is formulated as a multi-objectives optimization one. To overcome the computational complexity of an exact resolution, we propose an original pseudo-random approach based on the tabu search heuristic. Our proposal is able to take into consideration the required detection probability threshold of each point in the monitored area while minimizing the number of deployed sensors. Performances evaluations show that our proposal achieves a much better satisfaction rate than several other approaches proposed in the literature.

The main challenge in the development of future wireless communication systems is to provide users with a wide range of services across different radio access technologies through a single mobile terminal, while maintaining the quality of service requirements. Thus, the need for seamless inter-working between heterogeneous wireless communication systems consisting of multiple radio access technologies and overlapping networks emerges. In this article, we address the main issues that arise while implementing the interworking mechanisms between different radio access networks. An interworking mechanism based on IEEE 802.21 framework is proposed and described in detail. We combine concepts of autonomic computing in the design of the framework in order to use intelligence to provide flexibility, accessibility and transparency to the mobile users.

Wireless mesh networks have gained increasing interests, but the lack of security guarantee has retarded their deployment. Security solutions have applied preventive or reactive mechanisms, being inefficient to put all attacks off. We design a survivable architecture for ad hoc and mesh networks to enhance the network capability of providing essential services even in face of attacks or intrusions. Our approach integrates preventive, reactive and tolerant defense lines in a self-adaptive way. Based on our architecture, we create a survival path selection scheme, and evaluate it through simulations using urban mesh network mobility and propagation models. Results show a decrease in the impact of routing attacks with minimal performance loss.

Slander attacks represent a significant danger to distributed reputation systems. Malicious nodes may collude to lie about the reputation of a particular neighbor and cause serious damage to the overall trust evaluation system. This paper presents and analyzes a trust model robust to slander attacks in ad hoc networks. We provide nodes with a mechanism to build a trust relationship with its neighbors. The proposed model considers the recommendation of trustworthy neighbors and the previous experiences of the node itself. The interactions are limited to direct neighbors in order to scale on mobile networks. The results show the impact of slander attacks to our trust model. We analyze how the main parameters affect the trust evaluation process under a lying collusion attack. We show that our trust model tolerate almost 40% of liars.

This paper analyzes a trust model for mobile ad hoc networks. We provide nodes with a mechanism to build a trust relationship with its neighbors. The proposed model considers the recommendation of trustworthy neighbors and the experience of the node itself. The interactions are limited to direct neighbors in order to scale on mobile networks. The results show the efficiency and the trade-off of our model in the presence of mobility. We also analyze the advantages of considering the relationship maturity, i.e. for how long nodes know each other, to evaluate the trust level. The maturity parameter can decrease the trust level error up to 50%.

With current network simulators, simulation results are obtained from flat trace files via sequential data access. To speed up simulation output analysis, we propose to store the simulation traces into data warehouse. Our proposed framework relies on a three-layer architecture, with the intermediary database layer serving the trace file post processing services. The trace files are accessed through SQL-like queries which greatly enhances the flexibility of the post processing tools. Furthermore, the database paradigm allows to separate the packets data from the nodes send and receive operations and thus to remove redundant information between simulation events. The global system relies on a new trace file format based on the popular XML language. XML pointers are used to create relationships between data so that post processing tools can navigate into simulation outputs. The tests are carried out under the MonetDB database. The obtained results show considerable response time improvement compared to traditional sequential access mode.

Many efforts have been made to develop security solutions for MANETs. These networks are vulnerable to diverse types of attacks, where routing is a critical operation. Current secure routing protocols are based on preventive or reactive security mechanisms, monitoring node behavior or controlling the access to networks and information. These mechanisms are insufficient to put all attacks and intrusions off, motivating the use of techniques that can tolerate them as multipath routing. This work proposes a new scheme based on fuzzy logic to select better paths and to increase network survivability. Our approach considers different selection criteria, where some of them represent network status and others are issued by preventive, reactive and tolerant defense lines. Simulations have been carried out comparing AODV and AOMDV with a modified AOMDV protocol. Results show the survivability of our approach under different conditions.

In mobile wireless ad hoc networks (MANETs), layering is frequently broken to cope with changes on the medium. Layering is also violated in order to implement autonomic behavior, which depends on correlating data from various layers to identify relevant events. This paper proposes a networking plane, called MANET knowledge plane (MANKOP), that stores information concerning all protocol layers. This plane improves network performance, as protocols may employ a broader range of inputs on their algorithms. Moreover, being an information repository, MANKOP eases the deployment of self-optimizing and self-configuring mechanisms. To showcase our solution, we use MANKOP to build transmission power control aware protocols, which increases the throughput of the network by up to 280%.

The widespread success of the WLAN technology raises the need for the efficient management of the different access points and the associated wireless devices, especially when multimedia and other QoS demanding applications are employed. In this paper we propose an autonomic load balancing mechanism for WLAN networks and test its applicability for a Voice over WLAN (VoWLAN) use case. The algorithm takes into account the channel utilization, the spatial distribution of wireless devices and the QoS requirements of user applications. The autonomic aspect of our algorithm is related to the use of a knowledge plane, which is a conceptual authority that entertains detailed runtime knowledge about the network state in terms of the load on each access point, as well as the connection speed and application QoS requirements of each wireless device. We use OPNET to evaluate the effectiveness of our management solution and load balancing algorithm. The paper presents the conducted simulations and ends by a critique of the general applicability of our algorithm and suggestions for future work.

RFID is an automatic identification technique that stores and remotely retrieves data on small devices called tags. This technology enables tracking of people and objects and could support the conception of pervasive networks if identities are linked in real-time to their locations. We propose a scalable and robust 3-D localization method for RFID tags based only on connectivity information. Virtual landmarks are used to define inclusive and exclusive constraints, localize tags and estimate the accuracy of the calculations. Simulation results show that our algorithm provides fine-grained localization accuracy.

In this paper, we extend the differentiated deployment method which we have proposed in our previous paper by adding the connectivity constraint. We assume a fixed communication ray and a probabilistic detection model. We also consider that to each point in the deployment area is associated a detection probability threshold, which must be satisfied by our deployment method. Finally, we suppose that the detection probabilities thresholds of the area are geographically nonuniformly distributed. Our differentiated deployment problem is modeled as multi-objectives optimization problem, which we resolve using our proposed Tabu Search-based algorithm. A comparison is made with the methods found in the literature. The performances obtained by our method are much better in term of required number of sensors, generated detection probabilities, while ensuring the network connectivity.

We consider a channel aware scheduling for the downlink multi-service flows in orthogonal frequency division multiple access (OFDMA) based mobile WiMAX (Worldwide Interoperability for Microwave Access)system. We propose an intelligent medium access control (MAC) that adapts with the physical layer in response to the different QoS requirements of the diverse service flows in the system. This adaptation is represented by a joint packet scheduling and slot allocation scheme interaction in both MAC and PHY layers. Based on this interaction, a fair and efficient QoS guaranteed resource allocation for a mixed real-time and non real-time service flows is achieved. We provide extensive simulation results showing the performance aspects of the proposed cross-layer scheme.

One of the goals of next generation wireless networks (NGWNs) refers to the ability of supporting heterogeneous wireless access technologies. The objective is to provide a diverse range of seamlessly provide high-data rate multimedia services across different wireless networks. To achieve this, we must rely on seamless vertical handoff techniques. In this paper, we propose a distributed Simple Additive Weighting (SAW)-based vertical handoff mechanism. Our main goal is to reduce the processing overhead in the mobile terminal by delegating the calculation of handoff metrics for network selection to the Visiting Networks i.e. WiFi.

We consider a cross-layer scheme for the downlink multiuser Orthogonal Frequency Division Multiple Access (OFDMA) for mobile WiMAX (Worldwide Interoperability for Microwave Access) based on IEEE802.16e. We propose an intelligent Medium Access Control (MAC) that adapts with physical layer in response to the different QoS requirements of the service flows in the system. Our scheme satisfies the maximum delay requirement for real-time service flows as well as minimum reserved data rate for non real-time service flows sessions while maintaining a high capacity of the whole system. We provide extensive simulation results showing the performance aspects of the proposed cross-layer scheme.

In this paper we propose the enhancement of routing metrics through a more complete view of the physical channel. Using cross-layer optimizations, we develop the distribution based expected transmission count (DBETX), which improves the performance of the network in the presence of varying channels. Through observations of the wireless link, nodes estimate how the wireless link behaves. The proposed metric exploits this estimation to increase routing efficiency. The proposed metric is shown to outperform the conventional ETX metric in the presence of fading. The improvement over ETX increases with the network density because connectivity increases and more routing options become available. Results show a reduction of up to 26% in the Average Number of Transmissions per link and an increase of up to 32% in the end-to-end availability.

Wireless environment is expected to support heterogeneous wireless access technologies. The objective is the support of a diverse range of high-data rate multimedia services. The main issue in this environment is to provide a seamless vertical handoff mechanisms, which allow mobile users to handoff transparently from access technology to another. In this paper we propose a distributed handoff decision scheme to enhance service mobility using the Simple Additive Weighting (SAW) method in a distributed manner, under heterogeneous environments. Our main goal is to reduce the overload and power consumption in the mobile terminal, by delegating the calculation of handoff metrics for network selection to the Visiting Networks.

Most DiffServ admission control (AC) algorithms rely on tuning parameters to help in the decision making. Tuning these parameters is a difficult task, especially when one considers the problem of assuring QoS guarantees to individual flows. This paper proposes a method for helping the design of DiffServ AC algorithms based on non-linear programming optimization. It enables to find the values for the AC parameters that permits to satisfy the QoS guarantees for individual VoIP flows, while minimizing a cost function that represents the performance goals of the service provider. This approach is used to compare the performance of some commonly used DiffServ AC techniques and also to design a novel AC algorithm based on queue estimates.

IEEE802.16e is expected to support mobility for broadband wireless access with the capability of delivering high data rates over long ranges. We consider IEEE 802.216e scheme for scheduling and mapping higher layer data into the basic resource allocation units (slots) of OFDMA frames. Then, we introduce two simple allocation schemes that consider fair allocation among users with adaptive modulation. Both scheduling and mapping approaches are based on the quality of service (QoS) requirements of each service flow in terms of data rate and bit error rate (BER). The performance of both algorithms is studied by simulation. The results show that the proposed algorithms yield fairness among real-time and non real-time service flows as well as guaranteeing their constraint in term of QoS and outage probability.

Humans, by nature, have an innate urge to stay connected, share information and news, and collectively enhance our understanding of the world. The term connected society has become more appropriate with the Internet era. Home networking allows users to communicate and interact anywhere at anytime. This new and emerging technology will bring the Internet to the hands of the consumers, to every appliance in the house, and help interconnect people across the globe. It allows access to homes via the Internet when one is away, enabling security and energy management. In this paper, we discuss our approach for constructing a dynamic and secure "Inter-home" environment and tackling the challenges associated with it. The proposed overlay architecture -SPIN- is based on a P2P overlay protocol to interconnect the different home networks. Peer-to-peer networking has been recently popularized by file sharing systems such as Kaaza. We view the inter-home communications as more formalized home-network-extended construction of current P2P file sharing community.

One of the major concerns in wireless sensor networks is improving the network lifetime. In this paper, we propose an event reporting scheme and we show that based on it the average amount of energy required to report an event to the sink decreases when the network sensor density increases. Moreover, we prove that the speed of increasing the network lifetime goes up faster than that of the network density. Based on this result, we derive the minimal number of sensor nodes required to supervise a given area during a given period. Finally, we prove that these nodes must be deployed at the same time and not over different deployment phases.

International audience

Due to the lack of built-in quality of service support, IEEE 802.11 ad-hoc networks presents serious defies in meeting the demands of multimedia applications. To overcome such challenges, research in providing QoS guarantee in ad-hoc networks has been widely studied in latest years, and several QoS approaches have been proposed. Actually, cross-layer approaches have fascinated the attentions of researchers. They have interested at particular features of network performance by developing a multitude of cross-layer optimizations and adaptations implemented into several cross-layer architectures. We think that it is time that these various personal efforts be put into perspective; and that it is time to have a cross-layer architecture model which can serve as blueprint for development of cross-layer systems. In this paper, we take a step in that direction.

In this work, we focus on Service Level Agreement "SLA" driven nomadism management in wireless corporate networks. We adopt a novel top down approach in dealing with this problem. We aim at automatic equipment configuration based on high level company objectives and strategies for nomadism. For that, we propose a service-oriented management architecture, which starts at the specification of company objectives and strategies and down through SLAs until reaching instance level configurations.

In this paper, we study a new concept of traffic grooming in wavelength-division multiplexing (WDM) ring networks that aims at eliminating both the bandwidth underutilization and the scalability concerns that are typical of all-optical wavelength-routed ring networks. Our objective is to reduce the network cost while preserving the benefits of alloptical WDM ring networks. In order to assess the efficiency of our proposal, all underlying network costs are compared. These costs include that of the transceivers required at node level, as well as the number of wavelengths. Our results show that the proposed aggregation technique can significantly improve the resource utilization while reducing the network cost.

Optical networks are becoming an inevitable technology in the next generation Internet. Optical WDM networks require a control network for automatic and rapid configuration. A control plane is under standardization by the Internet Engineering Task Force (IETF) under the name generalized multiprotocol label switching (GMPLS). However, this control plane is unaware of the specifications of the services to be enforced. This work presents a policy-based management architecture adapted to an emerging kind of optical networks called hybrid photonic networks. Contributing to network flexibility, we present extensions to the management plane of these transparent wavelength and switching capable networks that provide the means to leverage their inherent capabilities. The proposed management architecture would provide optical network operators with the possibility to provision optical services, defined through high level service contracts, in an efficient and dynamic way.

Different QoS requirements of different applications can result in different preferences of the gateway that should be used by the mobile network to access the global Internet. In this context, automated solutions should be proposed offering a minimum complexity and maximum transparency to end users while being always best connected. In this paper, we propose a novel architecture that addresses the following issues and hence enforce the mobile network to Internet connectivity.

In this paper, we are interested in improving TCP flow performance when a short loss of 802.11 signal leads to lose segments. A short analytical study and a set of simulations in common wireless environments with signal losses due to distance or interferences are made to highlight the distinct MAC and TCP loss-recovery levels and the lack of interactions between them. This study shows the interest, in case of signal failure, to adapt one of the MAC parameters, the retry limit (RL), to reduce the drop in performance due to the inappropriate triggering of TCP congestion control mechanisms. Starting from this, a MAC-layer LDA (loss differentiation algorithm) is proposed. This LDA scheme is based on the adaptation of the RL parameter depending on the quality of the 802.11 wireless channel. The evaluation of the proposed scheme shows the important gain in performance obtained compared to the case where the RL is configured statically

In this paper, we propose a service-driven model for structuring WLANs into overlay networks of interacting wireless management communities. A wireless management community (WMC) is composed of a set of parties and is governed by a charter named the WMC-SLA (service level agreement). A WMC constitutes the basic unit of management upon which installed any form of service interaction between parties belonging to the wireless community. The WMC-SLA model is presented as a use case of a more general SLA model we name GSLA. The GSLA is an SLA information model that supports multi-party service relationships through a role-based mechanism. It is intended to catch up not only the complex nature of service interactivity intra and inter WMCs but also the broader range of SLA modeling of all sorts of IT business relationships. This model accommodates both granularity and modularity of behavioral specifications by having each party playing a role within a service relationship. It intends to bring a step towards SLA-driven management within pervasive service environments.

In this paper, we propose and evaluate a new concept of traffic aggregation in wavelength-division multiplexing (WDM) optical networks that aims at eliminating both the bandwidth underutilization and the scalability concerns that are typical of all-optical wavelength-routed networks. Our objective is to reduce the network cost while preserving the benefits of all-optical wavelength-routed networks. In order to assess the efficiency of our proposal, all underlying network costs are compared. These costs include that of the transceivers and cross-connect ports required at node level, as well as the number of wavelengths. Our results show that the proposed aggregation technique can significantly reduce the network cost

The present paper presents a framework for managing quality of service in future WDM core optical networks. These networks solve the bandwidth problem but transmit complexity to the control and management layers. Part of this complexity is handled by the generalized multiprotocol label switching (GMPLS) control plane. The latter, however, cannot tackle the new challenges posed by emerging applications requiring more than bandwidth guaranteed connections. In this paper, we first study the requirements of applications and the proposed quality of service in GMPLS, and then, we try to fill up the gap between both, with a focus on the transmission delay. The resulting framework will enable the optical network to meet the exigencies of new services

The wireless world is a new paradigm driven by both the growing market for higher-quality higher-speed wireless services, and the ubiquitous nature of both the Internet and the PC. In order to offer uninterrupted IP service, transparent mobility and fast re-authentication are important issues for the success of wide-area wireless IP infrastructures. In this work, we describe the design of a new architecture for secure and seamless mobility (SeSMo) support in heterogeneous environments. Our proposal introduces the use of an intelligent handoff decision mechanism for the discovery and the prediction of future access routers (ARs) and the generation of new session keys. An analytical analysis of the performance of SeSMo in terms of total signalling cost is also presented

One of the major concerns of optical network operators is related to improving the availability of services provided to their highest-class clients through the use of different protection schemes. However, the majority of the work concerning protection schemes considered the primary connections as equally important when contending for the use of the backup resources. As a first contribution we therefore propose an improvement of the existing shared protection schemes through the introduction of relative priorities among the different primary connections contending for the access to the protection path. Moreover, as a second contribution, we propose to include a novel service differentiation parameter, the service disruption rate of a connection, to provide differentiated services in a WDM mesh network, and we motivate the use of such a parameter with numerical examples. As a third contribution, we present a mathematical model for both the classical protection schemes and for the proposed priority-aware scheme. As a key distinguishing feature from existing literature we derive explicit analytic expressions for the average availability and service disruption rate resulting from the deployment of such schemes. By solving these models we then evaluate numerically the benefits of the service differentiation feature introduced in our scheme as well as the impact of the service disruption rate as service differentiator.

One of the main concerns in wireless sensor networks is improving the network lifetime. The basic idea underlying current studies is the partial utilization of the sensor network resources. Nevertheless, most of the existing works focus on the connection upholding issue, while neglecting the coverage problem. Therefore, we investigate, in this paper, the relationship between the network lifetime and the coverage problem. We show that controlling the density function, relying on efficient sensor nodes placement, can improve significantly network lifetime. In this regard, we propose an efficient placement algorithm addressing the case where the monitored area density is equal to two. Afterwards, we extend the algorithm dealing with the case where the terrain density is higher than two. Finally, we gauge the efficiency of our proposal through analytical models and simulations.

In this paper, we propose a practical approach to address how micro-mobility can be provided in an efficient way with continuous quality of service (QoS) support. Our proposal is based on multiprotocol label switching (MPLS) and mobile IP and relies on two-level hierarchy architecture. It supports two protocol variants. First, the fast handoff process, which anticipates the LSPs procedure setup with the neighboring locations where a mobile node (MN) may move to, is provided to reduce the service disruption. Second, a new mechanism based on the forwarding chain concept is proposed to track efficiently the host mobility within a domain. This concept can significantly reduce the registration updates cost and provide low handoff latency. Analytical models are developed and simulations are conducted to justify the benefits of our proposed mechanisms

With the rapid increase of wireless technologies and ubiquitous mobile computing devices, it is becoming a pressing need for developing new functionalities to support seamless handoff. However, developing and deploying new networking infrastructure is often a long and enduring process. In this paper, we present VIP (virtual interface prototype) a simple and efficient micro-mobility solution. The architecture requires very few changes to existing protocol stacks. In particular, no changes to non-mobile hosts are required. Moreover, the protocol adds no overhead to normal IP routing and delivery

Middleware for service creation in wireless sensor networks requires new architectures because of the tiny size of wireless sensors. This article preconizes a new service creation architecture named Archises (architecture of intelligent services for sensor networks). Archises supports mechanisms for self-organization, networking and energy optimization to build higher-level service structures in wireless sensor networks.

Packet-based optical access ring is becoming a promising solution in metropolitan networks. Its performance depends mainly on how optical resource sharing takes place among the different competing access nodes. This network architecture has mostly been explored with regard to synchronous transmission, i.e., slotted wavelength-division multiplexing (WDM) ring. However, in this paper, we focus on the performance of asynchronous transmission-based networks with variable packet sizes. Analytical models are presented in an attempt to provide explicit formulas that express the mean access delay of each node of the bus-based optical access network. We prove that in such a network, fairness problems are likely to arise between upstream and downstream nodes sharing a common data channel. Furthermore, we show that sharing the channel's available bandwidth fairly but arbitrarily between access nodes, as in slotted WDM rings, does not resolve the fairness problem in asynchronous system. In this regard, we exhibit the inherent limitations of the token bucket access rate-based algorithm once applied to asynchronous transmission bus-based networks. To alleviate the aforementioned problem, we device a new strategy called traffic control architecture using remote descriptors. The proposed solution is based on a preventive mechanism to grant access to the shared resource. As illustrated in this paper, the proposed solution alleviates the performance degradation and the resource underutilization, while achieving fairness among bus nodes.

Wireless local-area networks (WLANs) based on the IEEE 802.11 technology have been widely adopted for private use over the past few years. However, several issues remain concerns for large-scale deployment in corporate environments. Enforcing security and quality-of-service (QoS) has become a fundamental challenge to managing IEEE 802.11-based enterprise networks. In order to provide corporate networks with a global management solution, we have designed a service-oriented management system that enables user-centric service provisioning, while enforcing security and QoS requirements. As enterprises may be comprised of a number of distinct networks, we have extended our system to support the roaming of users between different enterprise sites. In this paper, we describe the design, implementation, and performance evaluation of our solution.

This document presents provisioning strategies for emerging hybrid optical networks. The idea is to make use of policy-based management that guides the behavior of a network through high-level declarative directives. In this regard and in the context of hybrid optical networks, policy rules are employed as the main means to extend the functionality of the control system and to complement its role in order to achieve the service provisioning.

In this paper, we propose and evaluate a new concept of traffic aggregation in mesh networks that aims to eliminate the bandwidth underutilization problem existing in all-optical wavelength routed networks. The proposed solution is based on the distribution of the aggregation process. So, instead of limiting the utilization of lightpaths capacity to the ingress node, each node along the path is allowed to fill on the fly this optical resource according to its availability. Therefore, the lightpath will be shared by several connections traveling from multiple ingress nodes to a single egress node. This technique combines the benefits of optical bypass and the statistical multiplexing gain. In order to gauge the value of the proposed solution, we formulate the problem using integer linear programming and study its performance through different scenarios using a prototype network. Our results show that distributed aggregation technique can improve significantly the network throughput and reduce the network cost.

Ad hoc wireless networks are power constrained since nodes operate with limited battery energy. Thus, energy consumption is crucial in the design of new ad hoc routing protocols. To design such protocols, we have to look away from the traditional minimum, hop routing schemes. In this, paper, we propose three extensions to the state-of-the-art shortest-cost routing algorithm, AODV. The discovery mechanism in these extensions (LEAR-AODV, PAR-AODV, and LPR-AODV) uses energy consumption as a routing metric. They reduce the energy consumption of the nodes by routing packets to their destination using energy-optimal routes. We show that these algorithms improve the network survivability by maintaining the network connectivity. They carry out this objective with low overhead and without affecting the other wireless network protocol layers.

The main problem to optimize wireless and mobile networks is the number of parameters that is playing a role in these systems. We can optimize the access to a service within such a network in different ways: Optimize battery capacity, optimize reliability of the network, optimize QoS, optimize the security, optimize the mobility management, and so on. We begin by proving that the TCP/IP architecture is not the best one in a specific wireless environment, the energy consumption on a Wi-Fi network. Then, we propose a new architecture, goal-based networking (GBN) architecture, using adaptable protocols named STP/SP protocols (smart transport protocol/smart protocol) able to optimize locally the communications through the networks. Finally we discuss the pros and cons of this new architecture.

This paper reports on the quality of service (QoS) requirements and the performance of virtual environment (VE) applications deployed in IP networks. We are interested specifically in systems that support communication with end-user through force feedback devices known as haptic interfaces. Little is known about networked haptic interfaces in VE. Our goal is to understand such application QoS requirements as well as the effect of other traffic when they co-exist in the same network. In this paper, we compare the peer-to-peer model with the client-server model. Our motivation is to deploy distributed haptic VE applications (DHVE) over a network connecting two departments of Queen's University of Belfast. This deployment will be used for educational purposes and for implementing further research in this area, and will be evaluated by end-users; hence, the essential realization of network-based DHVE under realistic network conditions. A set of experiments was conducted to achieve this aim and their results are presented in this paper.

Controlling handoff drops in a cellular network is a very important QoS issue. In order to keep the handoff-dropping probability as low as possible, we have designed a new predictive scheme for radio resource allocation. This scheme consists in dimensioning the amount of resources to reserve for handoffs in each cell. The solution proposed is based on a reservation mechanism with a threshold estimated according to the usage history of the resources in the cell. This estimation is done using the Kalman filter, a powerful mathematical tool. Evaluation of the proposed scheme demonstrates a real improvement in the handoff-dropping probability compared to the static reservation scheme.

An authentication model using secured smart cards implementing IP services is presented. In this model, some authentication functions usually found in the access network are moved inside the smart card. This innovative architecture simplifies current authentication schemes and helps to design new services.

In this paper, we propose a time-based channel reservation algorithm (TCRA) suitable for handover and call admission control procedures in future mobile satellite systems. These systems are characterized by a high rate of handover attempts, which can degrade significantly their performance. Therefore, we propose TCRA, a scheme that guarantees a null handover failure probability by using a channel reservation strategy in the cells to be crossed by the user. The performance of TCRA has been compared to the guaranteed handover scheme. The TCRA reservation method has the advantage of a better channel utilization by locking the resources only for their expected time of use. A mathematical model has been developed for both schemes, and its results have been validated through simulations.

Measuring the quality of multicast multi-layered applications based only on the amount of data that arrives at the receivers is insufficient in many circumstances. This paper proposes a three-metric approach that improves the global quality/fairness of the multicast sessions. We define a simple function that takes into account the density of satisfied users, the amount of allocated bandwidth in the multicast tree, and the degradation at the receivers. We analyze the proposed multicriteria algorithm in an environment with other competing flows and show the improvement of the global quality of multicast multi-layered applications.

This paper deals with the performance evaluation of different channel resource management techniques in low Earth orbit (LEO) satellite systems based on an Earth-fixed cell concept. Both fixed and mobile users have been considered resulting in several classes of users. Each class requires a given quality of service (QoS) and thus a fixed part of the shared resource. Two channel allocation techniques have been investigated: fixed channel allocation (FCA) and dynamic channel allocation (DCA). An analytical model has been derived to analyse the performance of the FCA scheme supporting different kinds of users. A performance comparison of FCA and DCA strategies has also been carried out by simulations as regards the blocking probabilities of each type of users.

Through a detailed analysis of theoretical and real MPEG-compressed video streams, this paper addresses the task of extracting deterministic parameters from such sources in order to provide deterministic service guarantees. We propose and analyze the single-input single-output (SISO) algorithm with quality adjustment to compute the coherent parameters for the XGOP-B deterministic traffic model. Contrary to other proposals, the SISO algorithm leads to a single set of parameters for each input traffic and does not ask for external decisions to perform this stage. Moreover, the accuracy/complexity can be adjusted by a special variable. Our results show that the proposed approach leads to improved accuracy and that the complexity can be decreased by three orders of magnitude.

In this paper, we investigate two approaches to handle UMTS traffic classes at the AAL2 and ATM layer over the Iub and Iur interfaces in the UMTS Terrestrial Radio Access Network (UTRAN). The first method is proposed to improve the (AAL2-) CPS scheduler by introducing the notion of traffic priority. The second method consists of multiplexing each UMTS traffic class into separate ATM connections with specific QoS. We present some simulation results on ATM/AAL2 performance to evaluate the two methods in terms of mean transmit delays, bounds of transmit delay and bandwidth efficiency.

This paper addresses the transport of real-time multimedia traffic generated by MPEG-2 applications over ATM best effort services (ABR, UBR+). To cope with network congestion and the unreliability of the ATM adaptation layer type 5 (AAL5), we propose a new service-specific convergence sublayer for audiovisual applications. The proposed AV-SSCS includes adaptive forward data error correction (FEC) based on Reed-Solomon and parity codes. With respect to network load and video packet loss ratio measured at the destination, the source can dynamically increase or reduce the FEC efficiency (i.e., the amount of data redundancy) to provide a higher protection to the video packet or a better use of the shared bandwidth respectively.

This paper deals with a proposal for IP cell-switching. This proposal is based on a fixed IPv6 packet length and a label-switching technology with different qualities of service. The label is provided through the flow label field of the IPv6 packet. The POS (Packet Over SONET) technology is used at the physical layer. A virtual path has to be established before sending the flow of IP cells. A signaling protocol is mandatory to set-up and to reserve the resource necessary to ensure the quality of service requested by the user. We analyze the existing reservation protocols that use a default path. Indeed, it should be more appropriate to choose a path providing the QoS negotiated between the sender and the receiver before reserving some resources. Most of the routing protocols determine the best path at the set-up time. However, this best path could become a congested path some time after. So, splitting the flow over multiple paths could give better performance than using just one path. Finally, we claim that RSVP could work as a signaling protocol at the basis of a resource reservation scheme in a label-switching environment. Moreover, this environment is well-adapted to the multicast paradigm.

Transmission of compressed video over ATM networks requires efficient data priority partition techniques. In association with intelligent cell discard schemes, these techniques aim to minimize the loss probability of critical information in the situation of congestion. We propose a new video-oriented priority data partition mechanism named the extended priority assignation scheme (ExPAS). This mechanism better uses the cell header and allows the definition of up to three service classes per connection. To evaluate its performance, we have also designed an adaptive cell dropping scheme which takes benefits of the new features. In comparison with previous priority partition techniques based on the cell loss probability (CLP) mechanism, ExPAS with the adaptive selective cell discard (A-SDC) scheme shows better results in minimizing cell losses of intra-coded frames.

We propose and evaluate a new MPEG based video delivery framework for use with ATM best effort services (e.g. available bit rate and unspecified bit rate). The presented framework relies on three components: a video oriented cell discarding scheme, which adaptively and selectively adjusts drop level to switch buffer occupancy and video cell payload types; a dynamic frame level priority data partition mechanism based on MPEG data structure and feedback from the network; and an enhanced ATM Adaptation Layer type 5 associated with a new slice based MPEG2 encapsulation strategy. This best effort video delivery framework is evaluated using simulation and real MPEG video data.

The goal is first to introduce performance monitoring aspects of asynchronous transfer mode (ATM) networks and then to focus on traffic and congestion control schemes. To deal with this performance monitoring management, a framework for defining a generic intelligent and integrated model for network management is described. As an example of the efficiency of this intelligent management architecture, we measure the performance of a new congestion control scheme. This scheme uses the cell loss priority (CLP) bit, the explicit forward congestion indicator and the explicit backward congestion indicator. The intelligent management uses different parameters and builds a complex but efficient control scheme. We show that this new control scheme allows performance to be increased by an order of magnitude.

A simple flow control mechanism, called RCT (rate control for end-to-end transport), is proposed for end-to-end transport in an asynchronous transfer mode (ATM) network. It reacts to instantaneous internal congestion as determined by the measured overload period. Transmission rate is adjusted by means of an adaptive window flow control mechanism that uses multiplicative decrease and linear increase algorithms. The RCT shows acceptable performance when the average round trip delay and the variance of the average value are small.>

The authors consider a multiclass open queueing network with class-dependent window flow control; that is, the total number of jobs of each class that may be present in the network cannot exceed a given value. A job that arrives at the network during the time that the current number of jobs of the same class is equal to the population constraint, is forced to wait in an external queue. A method is presented for obtaining an approximate solution of such a queueing network. The method is based on the use of an equivalent closed queuing network model, which is analyzed using an approximate product-form solution technique. The performance parameters of the original open queueing network are easily derived from the equivalent closed queueing network. Numerical results show that this method is fairly accurate.>

The main purpose of this paper is to evaluate the performance of the HDLC (high-level data link control) protocol (to be more precise, we only consider the asynchronous response mode), and to suggest and analyze some possible improvements. The performance criteria are maximum throughput and response time and the flow of data is bidirectional with nonuniform frame sizes. The mathematical model of the HDLC protocol developed here allows us to compute its performance as a function of the maximum window width according to the characteristics of the traffic and taking into account the transmission delays and the overheads.

Two methods of dealing with the overflow problem in packet switches are compared: switch-retransmission and host-retransmission. The comparison is based on approximate analytic models of tandem queueing networks and is verified by simulation.

In this paper a new method for analyzing complex queueing networks is proposed: the isolation method. As an example, we study packet switching networks with finite buffer size at each node.

A packet-switching network is considered as a tandem system of store-and-forward links. In this paper, it is shown that the maximum input traffic, with finite intermediate buffer size, is very sensitive to the distribution of the transmission time. The performance of two different protocols is compared under various distributions of transmission times.

A tandem queueing system with blocking due to finite waiting room is considered. Maximum throughput is studied by an approximation for several cases. The service time can depend on the number of customers; intermediate arrivals can also be allowed. Some special models with two stations in sequence and blocking are examined. These models are used for the performance evaluation of computer systems. In particular, the maximum throughput for a virtual memory operating system and for a node-to-node protocol in a computer network are obtained.

In this study, we are concerned with a simple error control protocol, the "send and wait" protocol, which uses the classical technique of positive acknowledgment and time-out periods. We first analyze the influence of the time-out on the packet transmission rate. Then we use a queuing analysis to obtain the ergodicity condition and to compute the buffer queue length probability distribution. Finally we compute buffer overflow when a finite number of packets are allowed to enter the node. This analysis allows us to obtain optimum values of the time-out in order to maximize throughput, or to minimize average transit delay through the node or buffer overflow probabilities.

We develop a method based on diffusion approximations in order to compute, under some general conditions, the queue length distribution for a queue in a network. Applications to computer networks and to time-sharing systems are presented.

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