Efficient Distributed Monitoring in 6LoWPAN Networks

International audienceMonitoring constrained, low power and lossy networks is essential to many operations including troubleshooting, forensics, performance management. The main challenge for the monitoring plane in these networks is to efficiently cope with both frequently changing topologies and constrained resources. We present a novel algorithm and the supporting framework that improves a poller-pollee based architecture. We empower the poller-pollee placement decision process and operation by exploiting available routing data to monitor nodes status. In addition, monitoring data is efficiently embedded in any messages flowing through the network, drastically reducing monitoring overhead. Our approach is validated through both simulation, implementation and deployment on a 6LoWPAN-enabled network. Results demonstrate that our approach is less aggressive and less resource consuming than its competitors

Performance analysis and improvement of InfiniBand networks. Modelling and effective Quality-of-Service mechanisms for interconnection networks in cluster computing systems.

The InfiniBand Architecture (IBA) network has been proposed as a new industrial standard with high-bandwidth and low-latency suitable for constructing high-performance interconnected cluster computing systems. This architecture replaces the traditional bus-based interconnection with a switch-based network for the server Input-Output (I/O) and inter-processor communications. The efficient Quality-of-Service (QoS) mechanism is fundamental to ensure the import at QoS metrics, such as maximum throughput and minimum latency, leaving aside other aspects like guarantee to reduce the delay, blocking probability, and mean queue length, etc. Performance modelling and analysis has been and continues to be of great theoretical and practical importance in the design and development of communication networks. This thesis aims to investigate efficient and cost-effective QoS mechanisms for performance analysis and improvement of InfiniBand networks in cluster-based computing systems. Firstly, a rate-based source-response link-by-link admission and congestion control function with improved Explicit Congestion Notification (ECN) packet marking scheme is developed. This function adopts the rate control to reduce congestion of multiple-class traffic. Secondly, a credit-based flow control scheme is presented to reduce the mean queue length, throughput and response time of the system. In order to evaluate the performance of this scheme, a new queueing network model is developed. Theoretical analysis and simulation experiments show that these two schemes are quite effective and suitable for InfiniBand networks. Finally, to obtain a thorough and deep understanding of the performance attributes of InfiniBand Architecture network, two efficient threshold function flow control mechanisms are proposed to enhance the QoS of InfiniBand networks; one is Entry Threshold that sets the threshold for each entry in the arbitration table, and other is Arrival Job Threshold that sets the threshold based on the number of jobs in each Virtual Lane. Furthermore, the principle of Maximum Entropy is adopted to analyse these two new mechanisms with the Generalized Exponential (GE)-Type distribution for modelling the inter-arrival times and service times of the input traffic. Extensive simulation experiments are conducted to validate the accuracy of the analytical models

Routing based Roles Assignment for Monitoring 6LowPAN Networks

International audienceIn this work, we present a novel approach to assign monitoring roles in constrained, low power and lossy networks using available local information provided by the routing layer. The resulting monitoring architecture is adaptive taking benefit from the reactivity of the routing protocol when dynamic changes occur due to connectivity or nodes movement. The simulation results reveal that our assignment approach is more efficient, less aggressive and less resources consuming than its competitors

Understanding Urban Human Mobility for Network Applications

Understanding urban human mobility is crucial for various mobile and network applications. This thesis addresses two key challenges presented by mobile applications, namely urban mobility modeling and its applications in Delay Tolerant Networks (DTNs). First, we model urban human mobility with transportation mode information. Our research is based on two real-life GPS datasets containing approximately 20 and 10 million GPS samples. Previous research has suggested that the trajectories in human mobility have statistically similar features as Lévy Walks. We attempt to explain the Lévy Walks behavior by decomposing them into different classes according to the different transportation modes, such as Walk/Run, Bike, Train/ Subway or Car/Taxi/Bus. We show that human mobility can be modelled as a mixture of different transportation modes, and that these single movement patterns can be approximated by a lognormal distribution rather than a power-law distribution. Then, we demonstrate that the mixture of the decomposed lognormal flight distributions associated with each modality is a power-law distribution, providing an explanation for the emergence of Lévy Walks patterns that characterize human mobility patterns. Second, we find that urban human mobility exhibits strong spatial and temporal patterns. We leverage such human mobility patterns to derive an optimal routing algorithm that minimizes the hop count while maximizing the number of needed nodes in DTNs. We propose a solution framework, called Ameba, for timely data delivery in DTNs. Simulation results with experimental traces indicate that Ameba achieves a comparable delivery ratio to a Flooding-based algorithm, but with much lower overhead. Third, we infer the functions of the sub-areas in three cities by analyzing urban mobility patterns. The analysis is based on three large taxi GPS datasets in Rome, San Francisco and Beijing containing 21, 11 and 17 million GPS points, respectively. We categorize the city regions into four categories, workplaces, entertainment places, residential places and other places. We show that the identification of these functional sub-areas can be utilized to increase the efficiency of urban DTN applications. The three topics pertaining to urban mobility examined in the thesis support the design and implementation of network applications for urban environments.Ihmisen liikkumisen ymmärtäminen on erittäin tärkeää monille mobiiliverkkojen sovelluksille. Tämä väitöskirja käsittelee mobiilikäyttäjien liikkuvuuden mallintamista ja sen soveltamista viiveitä sietävään tiedonvälitykseen urbaanissa ympäristössä. Aloitamme mallintamalla mobiilikäyttäjien liikkuvuutta ottaen huomioon kulkumuodon. Tutkimuksemme perustuu kahteen laajaan GPS-data-aineistoon. Käytetyissä data-aineisto koostuu 10 ja 20 miljoonan havaintopisteen kulkuvälineet sisältävistä GPS-tiedoista. Aikaisemmat tutkimukset ovat ehdottaneet, että liikkuvuusmalleilla on samankaltaisia tilastollisia ominaisuuksia kuin Lévy-kävelyillä. Tutkimuksemme selittää Lévy-kävelyiden käyttäytymisen jakamalla ne erilaisiin kulkumuotoihin, kuten kävely/juoksu, polkupyöräily, juna/metro tai auto/taksi/bussi. Näytämme, että ihmisten liikkuvuus voidaan mallintaa eri kulkumuotojen yhdistelminä ja että yksittäiset liikkuvuusmallit voidaan arvioida logaritmisella normaalijakaumalla paremmin kuin potenssilakia noudattavalla jakaumalla. Lisäksi osoitamme, että yhdistelmä kävelyjen lavennetusta logaritmisesta normaalijakaumasta eri kulkumuotojen kanssa on potenssilakia noudattava jakauma, joka selittää ihmisten liikkuvuusmalleja luonnehtivien Lévy-kävelymallien esiintymisen. Toiseksi osoitamme, että urbaanin ihmisen liikkuvuuteen kuuluu vahvoja aikaan ja paikkaan liittyviä malleja. Johdamme näistä ihmisten liikkuvuusmalleista optimaalisen reititysalgoritmin, joka minimoi tarvittavien hyppyjen määrän ja maksimoi tarvittavien solmujen määrän viiveitä sietävissä verkoissa. Esitämme ratkaisuksi arkkitehtuurikehyksen nimeltä Ameba, joka takaa oikea-aikaisen viestien välityksen viiveitä sietävissä verkoissa. Simulointitulosten perusteella Ameba saavuttaa tulvitukseen perustuvien algoritmien kanssa vertailukelpoisen viestien kuljetussuhteen, mutta pienemmällä resurssikustannuksella. Kolmanneksi päättelemme maantieteellisten osa-alueiden funktiot analysoimalla kolmen kaupungin urbaaneja liikkumismalleja. Analyysi perustuu kolmeen laajaan taksien GPS-paikkatiedosta. GPS-data on kerätty Roomassa, San Franciscossa, ja Pekingissä ja koostuu 21, 11, ja 17 miljoonasta havaintopisteestä. Luokittelemme kaupunkien alueet neljään luokkaan: työpaikat, viihde-, asuin-, ja muut paikat. Näytämme, että näiden luokkien tunnistamista voidaan käyttää parantamaan viiveitä sietävien verkkojen sovellusten tehokkuutta. Kaikki tässä väitöskirjassa käsitellyt mobiilikäyttäjien liikkuvuuden mallintamisen aihepiirit edesauttavat urbaanien ympäristöjen verkkojen sovellusten suunnittelua ja toteutusta

Space-Fluid Adaptive Sampling by Self-Organisation

A recurrent task in coordinated systems is managing (estimating, predicting, or controlling) signals that vary in space, such as distributed sensed data or computation outcomes. Especially in large-scale settings, the problem can be addressed through decentralised and situated computing systems: nodes can locally sense, process, and act upon signals, and coordinate with neighbours to implement collective strategies. Accordingly, in this work we devise distributed coordination strategies for the estimation of a spatial phenomenon through collaborative adaptive sampling. Our design is based on the idea of dynamically partitioning space into regions that compete and grow/shrink to provide accurate aggregate sampling. Such regions hence define a sort of virtualised space that is "fluid", since its structure adapts in response to pressure forces exerted by the underlying phenomenon. We provide an adaptive sampling algorithm in the field-based coordination framework, and prove it is self-stabilising and locally optimal. Finally, we verify by simulation that the proposed algorithm effectively carries out a spatially adaptive sampling while maintaining a tuneable trade-off between accuracy and efficiency

Handoff Triggering and Network Selection Algorithms for Load-Balancing Handoff in CDMA-WLAN Integrated Networks

This paper proposes a novel vertical handoff algorithm between WLAN and CDMA networks to enable the integration of these networks. The proposed vertical handoff algorithm assumes a handoff decision process (handoff triggering and network selection). The handoff trigger is decided based on the received signal strength (RSS). To reduce the likelihood of unnecessary false handoffs, the distance criterion is also considered. As a network selection mechanism, based on the wireless channel assignment algorithm, this paper proposes a context-based network selection algorithm and the corresponding communication algorithms between WLAN and CDMA networks. This paper focuses on a handoff triggering criterion which uses both the RSS and distance information, and a network selection method which uses context information such as the dropping probability, blocking probability, GoS (grade of service), and number of handoff attempts. As a decision making criterion, the velocity threshold is determined to optimize the system performance. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations. The optimal velocity threshold is adjusted to assign the available channels to the mobile stations using four handoff strategies. The four handoff strategies are evaluated and compared with each other in terms of GOS. Finally, the proposed scheme is validated by computer simulations

Optimisation de la capacité et de la consommation énergétique dans les réseaux maillés sans fil

Les réseaux maillés sans fil sont une solution efficace, de plus en plus mise en œuvre en tant qu infrastructure, pour interconnecter les stations d accès des réseaux radio. Ces réseaux doivent absorber une croissance très forte du trafic généré par les terminaux de nouvelle génération. Cependant, l augmentation du prix de l énergie, ainsi que les préoccupations écologiques et sanitaires, poussent à s intéresser à la minimisation de la consommation énergétique de ces réseaux. Ces travaux de thèse s inscrivent dans les problématiques d optimisation de la capacité et de la minimisation de la consommation énergétique globale des réseaux radio maillés. Nous définissons la capacité d un réseau comme la quantité de trafic que le réseau peut supporter par unité de temps. Ces travaux s articulent autour de quatre axes. Tout d abord, nous abordons le problème d amélioration de la capacité des réseaux radio maillés de type WIFI où l accès au médium radio se base sur le protocole d accès CSMA/CA. Nous mettons en lumière, les facteurs déterminants qui impactent la capacité du réseau, et l existence d un goulot d étranglement qui limite cette capacité du réseau. Ensuite, nous proposons une architecture de communication basée sur l utilisation conjointe de CSMA/CA et de TDMA afin de résoudre ce problème de goulot d étranglement. Dans la deuxième partie de cette thèse, nous nous intéressons aux réseaux maillés sans fil basés sur un partage des ressources temps-fréquence. Afin de calculer des bornes théoriques sur les performances du réseau, nous développons des modèles d optimisation basés sur la programmation linéaire et la technique de génération de colonnes. Ces modèles d optimisation intègrent un modèle d interférence SINR avec contrôle de puissance continue et variation de taux de transmission. Ils permettent, en particulier, de calculer une configuration optimale du réseau qui maximise la capacité ou minimise la consommation d énergie. Ensuite, dans le troisième axe de recherche, nous étudions en détail le compromis entre la capacité du réseau et la consommation énergétique. Nous mettons en évidence plusieurs résultats d ingénierie nécessaires pour un fonctionnement optimal d un réseau maillé sans fil. Enfin, nous nous focalisons sur les réseaux cellulaires hétérogènes. Nous proposons des outils d optimisation calculant une configuration optimale des stations de base qui maximise la capacité du réseau avec une consommation efficace d énergie. Ensuite, afin d économiser l énergie, nous proposons une heuristique calculant un ordonnancement des stations et leur mise en mode d endormissement partiel selon deux stratégies différentes, nommées LAFS et MAFS.Wireless mesh networks (WMN) are a promising solution to support high data rate and increase the capacity provided to users, e.g. for meeting the requirements of mobile multimedia applications. However, the rapid growth of traffic load generated by the terminals is accompanied by an unsustainable increase of energy consumption, which becomes a hot societal and economical challenges. This thesis relates to the problem of the optimization of network capacity and energy consumption of wireless mesh networks. The network capacity is defined as the maximum achievable total traffic in the network per unit time. This thesis is divided into four main parts. First, we address the problem of improvement of the capacity of 802.11 wireless mesh networks. We highlight some insensible properties and deterministic factors of the capacity, while it is directly related to a bottleneck problem. Then, we propose a joint TDMA/CSMA scheduling strategy for solving the bottleneck issue in the network. Second, we focus on broadband wireless mesh networks based on time-frequency resource management. In order to get theoretical bounds on the network performances, we formulate optimization models based on linear programming and column generation algorithm. These models lead to compute an optimal offline configuration which maximizes the network capacity with low energy consumption. A realistic SINR model of the physical layer allows the nodes to perform continuous power control and use a discrete set of data rates. Third, we use the optimization models to provide practical engineering insights on WMN. We briefly study the tradeoff between network capacity and energy consumption using a realistic physical layer and SINR interference model. Finally, we focus on capacity and energy optimization for heterogeneous cellular networks. We develop, first, optimization tools to calculate an optimal configuration of the network that maximizes the network capacity with low energy consumption. We second propose a heuristic algorithm that calculates a scheduling and partial sleeping of base stations in two different strategies, called LAFS and MAFS.VILLEURBANNE-DOC'INSA-Bib. elec. (692669901) / SudocSudocFranceF

Bond Percolation in Small-World Graphs with Power-Law Distribution

Full-bond percolation with parameter p is the process in which, given a graph, for every edge independently, we keep the edge with probability p and delete it with probability 1-p. Bond percolation is studied in parallel computing and network science to understand the resilience of distributed systems to random link failure and the spread of information in networks through unreliable links. Moreover, the full-bond percolation is equivalent to the Reed-Frost process, a network version of SIR epidemic spreading. We consider one-dimensional power-law small-world graphs with parameter ? obtained as the union of a cycle with additional long-range random edges: each pair of nodes {u,v} at distance L on the cycle is connected by a long-range edge {u,v}, with probability proportional to 1/L^?. Our analysis determines three phases for the percolation subgraph G_p of the small-world graph, depending on the value of ?. - If ? < 1, there is a p < 1 such that, with high probability, there are ?(n) nodes that are reachable in G_p from one another in ?(log n) hops; - If 1 < ? < 2, there is a p < 1 such that, with high probability, there are ?(n) nodes that are reachable in G_p from one another in log^{?(1)}(n) hops; - If ? > 2, for every p < 1, with high probability all connected components of G_p have size ?(log n)

Modeling and defense against propagation of worms in networks

Worms are widely believed to be one of the most serious challenges in network security research. In order to prevent worms from propagating, we present a microcosmic model, which can benefit the security industry by allowing them to save significant money in the deployment of their security patching schemes