Bruno Astuto A. Nunes

University of Nice-Sophia Antipolis, Nice, Provence-Alpes-Côte d'Azur, France

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Publications (15)4.4 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: In this article, we discuss user-centric networks as a way of, if not completely solving, considerably mitigating the problem of sharing limited network capacity and resources efficiently and fairly. UCNs are self-organizing networks where the end user plays an active role in delivering networking functions such as providing Internet access to other users. We propose to leverage the recently proposed SDN paradigm to enable cooperation between wireless nodes and provide capacity sharing services in UCNs. Our SDNbased approach allows coverage of existing network infrastructure (e.g., WiFi or 3GPP) to be extended to other end users or ad hoc networks that would otherwise not be able to have access to network connectivity and services. Moreover, the proposed SDN-based architecture also takes into account current network load and conditions, and QoS requirements. Another important feature of our framework is that security is an integral part of the architecture and protocols. We discuss the requirements for enabling capacity sharing services in the context of UCNs (e.g., resource discovery, node admission control, cooperation incentives, QoS, security) and how SDN can aid in enabling such services. The article also describes the proposed SDN-enabled capacity sharing framework for UCNs.
    IEEE Communications Magazine 09/2014; 52(9):28-36. · 3.66 Impact Factor
  • Bruno Astuto Arouche Nunes, Katia Obraczka
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    ABSTRACT: User mobility is of critical importance when designing mobile networks. In particular, "waypoint" mobility has been widely used as a simple way to describe how humans move. This paper introduces the first modeling framework to model waypoint-based mobility. The proposed framework is simple, yet general enough to model any waypoint-based mobility regimes. It employs first order ordinary differential equations to model the spatial density of participating nodes as a function of (1) the probability of moving between two locations within the geographic region under consideration, and (2) the rate at which nodes leave their current location. We validate our model against real user mobility recorded in GPS traces collected in three different scenarios. Moreover, we show that our modeling framework can be used to analyze the steady-state behavior of spatial node density resulting from a number of synthetic waypoint-based mobility regimes, including the widely used Random Waypoint model. Another contribution of the proposed framework is to show that using the well-known preferential attachment principle to model human mobility exhibits behavior similar to random mobility, where the original spatial node density distribution is not preserved. Finally, as an example application of our framework, we discuss using it to generate steady-state node density distributions to prime mobile network simulations.
    Wireless Networks 05/2014; 20(4). · 0.74 Impact Factor
  • Network Protocols (ICNP), 2013 21st IEEE International Conference on; 10/2013
  • Bruno Astuto Arouche Nunes, Katia Obraczka, Abel Rodrigues
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    ABSTRACT: In this paper, we introduce a user mobility modeling framework that accounts for both the users' social structure as well as the geographic diversity of the region of interest. SAGA, or Socially- and Geography-Aware mobility model, captures social features through the use of communities which cluster users with similar features such as average time in a cell, average speed, and pause time. SAGA accounts for geographic diversity by considering that different communities exhibit different interests for different locales; therefore, different communities are attracted to certain physical locations with different intensities. Besides introducing SAGA, the contributions of this work include: a model calibration approach based on formal statistical procedures to extract social structures and geographical diversity from real traces and set SAGA's parameters; and validation of SAGA by applying it to real mobility traces. Our experimental results show that, when compared to existing mobility regimes such as Random-Waypoint and Preferential-Attachment based mobility, SAGA is able to preserve the desired non-uniform node spatial density present in real user mobility, creating and maintaining clusters and accounting for differential node popularity and transitivity.
    Proceedings of the 15th ACM international conference on Modeling, analysis and simulation of wireless and mobile systems; 10/2012
  • Katia Obraczka, Bruno A. A. Nunes
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    ABSTRACT: This paper introduces a modeling framework to analyze spatial node density in mobile networks under “waypoint”-like mobility regimes. The proposed framework is based on a set of first order ordinary differential equations (ODEs) that take as parameters (1) the probability of going from one subregion of the mobility domain to another and (2) the rate at which a node decides to leave a given subregion. We validate our model by using it to describe the steady-state behavior of real user mobility recorded by GPS traces in different scenarios. To the best of our knowledge, this is the first node density modeling framework generic enough that can be applied to any “waypoint”-based mobility regime.
    Proceedings of the 2012 IEEE 9th International Conference on Mobile Ad-Hoc and Sensor Systems (MASS); 10/2012
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    ABSTRACT: Mobility models are used to represent the movement behavior of mobile devices in ad hoc networks simulations. As a consequence, the results obtained via simulations for specific characteristics related to mobile ad hoc networks are expected to be significantly dependent upon the choice of a particular mobility model under consideration. In this context, we present in this work a new mobility model, based on Birth-Death stochastic processes, which allows us to adjust mobility parameters according to the movement profile intended to be represented. The impact of mobility models in the simulation of ad hoc networks is observed through the performance evaluation of metrics related to the AODV routing protocol, by comparing the results obtained under the Birth-Death framework used in this paper with those calculated under the Generic Individual Mobility Markovian and the Random Waypoint models. KeywordsMANETs–mobility model–birth-death process
    08/2011: pages 238-250;
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    Bruno Astuto A. Nunes, Katia Obraczka
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    ABSTRACT: �bstract— In this paper analyzed WLAN-� GPS-� and synthetic traces that record mobility in a variety of network environments. We observe that from a macroscopic levelhuman mobility is symmetric. In other wordsthe number of users that move from pointto point B approximates the number of users that go in the opposite directioni.e.� from B to �. We show that this type of symmetry is more accentuated in synthetic mobility modelsin particularin random way-point mobility. We also study the direction of movement which also exhibits symmetric behavior in both real- as well as synthetic mobility. Additional contributions of our work include metrics to quantify mobility symmetry. We conclude the paper with a discussion of possible applications of our results in mobile networking. IIntroduction Node mobility is a key factor in the design and perfor- mance evaluation of mobile networks and their protocols and mobility characterization has attracted consider- able attention from the networking research community. Evaluation studies of early mobile networks and their protocols used most of the time "synthetic" mobility models such as random walk, Brownian motion, and the random way-point (RWP) model (1), just to mention a few. The RWP, in particular, has been one of the most used mobility models for evaluating mobile networks which motivated several studies that scrutinized its be- havior, identified a number of undesirable features (2), as well as proposed variations to improve its behavior. More recently, motivated in part by the problems associated with the RWP and recognizing the impor- tance of employing more realistic mobility scenarios when designing and evaluating mobile networks, there has been considerable interest in using real mobility traces and developing models that reflect real mobility. Crawdad (3), is an example of an initiative to make real mobility traces widely available to network researchers. In this paper, also motivated by the trend towards employing real mobility to design and evaluate wireless networks, we study different types of traces obtained by recording user mobility. Our goal is to identify patterns, extract features, and define metrics to characterize the spatial behavior of human mobility. As a result, we
    12th IEEE International Symposium on a World of Wireless, Mobile and Multimedia Networks, WOWMOM 2011, Lucca, Italy, 20-24 June, 2011; 01/2011
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    Bruno Astuto A. Nunes, Katia Obraczka
    IEEE 8th International Conference on Mobile Adhoc and Sensor Systems, MASS 2011, Valencia, Spain, October 17-22, 2011; 01/2011
  • Smart Spaces and Next Generation Wired/Wireless Networking, 11th International Conference, NEW2AN 2011, and 4th Conference on Smart Spaces, ruSMART 2011, St. Petersburg, Russia, August 22-25, 2011. Proceedings; 01/2011
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    ABSTRACT: In this paper, we explore a novel approach to end-to-end round-trip time (RTT) estimation using a machine-learning technique known as the Experts Framework. In our proposal, each of several "experts" guesses a fixed value. The weighted average of these guesses estimates the RTT, with the weights updated after every RTT measurement based on the difference between the estimated and actual RTT. Through extensive simulations we show that the proposed machine-learning algorithm adapts very quickly to changes in the RTT. Our results show a considerable reduction in the number of retransmitted packets and a increase in goodput, in particular on more heavily congested scenarios. We corroborate our results through "live" experiments using an implementation of the proposed algorithm in the Linux kernel. These experiments confirm the higher accuracy of the machine learning approach with more than 40% improvement, not only over the standard TCP, but also over the well known Eifel RTT estimator.
    01/2011;
  • B.A.A. Nunes, K. Obraczka
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    ABSTRACT: In this paper we show that human mobility exhibits "persistent" behavior in terms of the spatial density distribution of the mobile nodes over time. Using real mobility traces, we observe that the original non-homogeneous node spatial density distribution, where some regions may be quite dense while others may be completely deserted, is maintained at different instants of time. We also show that mobility models that select the next node position based on the position of other nodes, a la "preferential attachment", do not preserve the original spatial node density distribution and lead to behavior similar to random mobility as exemplified by the Random Waypoint model. To the best of our knowledge, this is the first time that these phenomena have been reported. Based on these observations, we propose a simple mobility model that preserves the desired spatial density distribution. Moreover, when simulating the operation of a network moving according to the proposed model, we found that performance results expressed by a number of network metrics also match closely results obtained under mobility governed by real traces. We also compare our results to models whose steady-state do not preserve the original non-homogeneous density distribution and show that network performance under such regimes deviates from performance under real trace mobility.
    Mobile Adhoc and Sensor Systems (MASS), 2011 IEEE 8th International Conference on; 01/2011
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    ABSTRACT: During the last decade, the success and popularity of wire- less standards such as IEEE 802.11 have drawn the attention of the research community to wireless networks. A great amount of effort has been invested into research in this area, most of which relies heavily on simulation and analysis techniques. However, simulations do not precisely control hardware in- terrupts, packet timing and real physical and MAC layer behaviors. As a result, simulation results need to be validated by real implementations, which is evident by the change in focus of research activities increasingly moving towards real implementations, including the deployment of testbeds as a main tool to analyze network protocol functionality. Under this context, we present an overview of SCORPION (Santa Cruz mObile Radio Platform for Indoor and Outdoor Networks), a heterogeneous wireless networking testbed that includes a variety of nodes ranging from ground vehicles to autonomous aerial vehicles. The purpose of SCORPION to is to deploy and investigate nascent networking protocols using a variety of mobile platforms utilizing structured as well as unstructured mobility patterns. A. Goal
    ACM SIGMOBILE Mobile Computing and Communications Review 01/2009; 13:65-68.
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    Luís Felipe M. de Moraes, Bruno Astuto A. Nunes
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    ABSTRACT: In this work we present a calibration-free system for locating wireless local area network devices, based on the radio frequency characteristics of such networks. Calibration procedures are applied in a great number of proposed location techniques and are considered to be not practical or a considerable barrier to wider adoption of such methods. Thus, we addressed issues related to some aspects of location systems through, an architecture based on wireless sniffers and by constructing a location model based on signal propagation models, in which its parameters are calculated in real time. This guarantee good self-sufficiency and adaptation capacity to the proposed system, once it does not need human intervention to work, neither from the network administrator or the wireless user being located. Moreover, a probabilistic method was used for estimating wireless devices positions, based on the previous constructed model. We later demonstrate the feasibility of our approach by reporting results of field tests in which the proposed technique was implemented and validated in a real-world indoor environment.
    Proceedings of the Forth ACM International Workshop on Mobility Management & Wireless Access, MOBIWAC 2006, Terromolinos, Spain, October 2, 2006; 01/2006
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  • Bruno A. A. Nunes
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    ABSTRACT: A system for locating wireless network devices in a local area,based upon radio-frequency characteristics was proposed and anal yzed in (1). In the present work, the construction of the model considered in (1) is modified to con- sider the characteristics of the monitored environment, su ch as walls, windows, closets, and other types of obstacles. Taking in considerat ion these characte- ristics, the precision of the system grew up to 13%, without an y increase in the complexity or effort of implementation. Resumo. Um sistema para localizac ¸˜ ao de dispositivos em redes locais sem fio, baseado em caracter´ isticas de r´ adio-frequˆ

Publication Stats

38 Citations
4.40 Total Impact Points

Institutions

  • 2014
    • University of Nice-Sophia Antipolis
      Nice, Provence-Alpes-Côte d'Azur, France
  • 2009–2012
    • University of California, Santa Cruz
      • Department of Computer Engineering
      Santa Cruz, California, United States
  • 2011
    • Loyola University Maryland
      Baltimore, Maryland, United States
  • 2006–2011
    • Federal University of Rio de Janeiro
      Rio de Janeiro, Rio de Janeiro, Brazil