Events agenda

6 Jul
2011

Obscure Giants: Detecting the Provider-Free ASes

Syed Hasan, Research Assistant at IMDEA Networks
We study the detection of the provider-free AS set (PFS), i.e., the set of those Autonomous Systems (ASes) that reach the entire Internet without paying anyone for the traffic delivery. Using trustworthy but non-verifiable sources for sanity checks, we derive the PFS from public datasets of inter-AS economic relationships. Whereas a straightforward method for extracting the PFS performs poorly because the datasets are noisy, we develop a more sophisticated Temporal Cone (TC) algorithm that relies on topological statistics and exploits the temporal diversity of the datasets. The evaluation shows that our TC algorithm detects the PFS with a high accuracy.
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29 Jun
2011

Where are my followers? Understanding the Locality Effect in Twitter

Dr. Ruben Cuevas, Assistant Professor at Universidad Carlos III de Madrid
Twitter is one of the most used applications in the current Internet with more than 200M accounts created so far. As other large-scale systems Twitter can obtain benefit by exploiting the Locality effect existing among its users. In this paper we perform the first comprehensive study of the Locality effect of Twitter. For this purpose we have collected the geographical location of around 1M Twitter users and 16M of their followers. Our results demonstrate that language and cultural characteristics determine the level of Locality expected for different countries.
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22 Jun
2011

FakeDetector: A measurement-based tool to get rid out of fake content in your BitTorrent Downloads

Michal Kryczka, Research Assistant, Institute IMDEA Networks
Fake content represents an important portion of those files shared in BitTorrent. In this paper we conduct a large scale measurement study in order to analyse the fake content publishing phenomenon in the BitTorrent Ecosystem. Our results reveal that a few tens of users are responsible for 90% of the fake content. Furthermore, more than 99% of the analysed fake files are linked to either malware or scam websites. This creates a serious thread for the BitTorrent ecosystem.
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15 Jun
2011

Research in Collaborative Haptic-Audio-Visual Environments

Abdulmotaleb El Saddik, University Research Chair and Professor, School of Information Technology and Engineering, University of Ottawa.
Multimedia and information technology are reaching limits in terms of what can be done in multimedia applications with only sight and sound. The next critical step is to bring the sense of “touch” over network connections, which is commonly known as Tele-haptics. Haptics, a term which was derived from the Greek verb “haptesthai” meaning “to touch”, introduces the sense of touch and force into the human-computer interaction. Currently, research on haptics is broadly categorized into human haptics, machine haptics, and computer haptics. Human haptics is mostly conducted by psychologists to study the mechanism of the “touch” modality, while machine haptics refers to the design of haptic devices to reproduce the sense of “touch”.
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8 Jun
2011

Proportional Fairness and its Relationship with Multi-class Queueing Networks

Neil Walton, Assistant Professor at University of Amsterdam
We consider multi-class single server queueing networks that have a product form stationary distribution. A new limit result proves a sequence of such networks converges weakly to a stochastic flow level model. The stochastic flow level model found is insensitive. A large deviation principle for the stationary distribution of these multi-class queueing networks is also found. Its rate function has a dual form that coincides with proportional fairness. We then give the first rigorous proof that the stationary throughput of a multi-class single server queueing network converges to a proportionally fair allocation.
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1 Jun
2011

Energy-efficient fair channel access for IEEE 802.11 WLANs

Andres Garcia Saavedra, PhD Candidate, NETCOM Research Group
​Abstract-Greening the communication protocols is nowadays recognized as a primary design goal of future global network infrastructures. The objective function for optimization is the amount of information transmitted per unit of energy, replacing the amount of information transmitted per unit of time (i.e., throughput). In this paper we investigate the case of IEEE 802.11- based WLANs and first show that, given the existing diversity of power consumption figures among mobile devices, performing a fair allocation of resources among devices is challenging.
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24 May
2011

Discovering internet load balancing through reordering measurement

Speaker: Iljitsch van Beijnum, Research Assistant, Institute IMDEA Networks Location: Room 4. 1F03, Telematics Department, Torres Quevedo Building, University Carlos III of Madrid, Avda. Universidad, 30, 28911 Leganes – Madrid Date: May 25th 2011, 13:00 Organization: NETCOM Research Group (Telematics Department, University Carlos III of Madrid, Spain); Institute IMDEA Networks (Madrid, Spain)   The conference will be conducted in English
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19 May
2011

Game Theory for Cooperative Networks

Dr. Walid Saad, Postdoctoral Research Associate at the Electrical Engineering Department at Princeton University
Game theoretical techniques have recently become prevalent in a wide range of engineering applications, notably, in wireless and communication networks. With the emergence of novel networking paradigms such as cognitive radio or cooperative communications and the need for self-organizing and decentralized networks, it has become imperative to seek game theoretical tools that allow studying and analyzing the interactions of the nodes in future communication networks. In this talk, following a brief overview on the fundamentals and potential of game theory, we put a particular emphasis on coalitional game theory, which is a branch of game theory that deals with cooperative behavior.
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18 May
2011

3rd IMDEA Networks Annual International Workshop: Internet Science

Members of IMDEA Networks’ Scientific Council and invitees
Institute IMDEA Networks annually holds a by-invitation-only thematic workshop in Madrid. The workshop accompanies a meeting of our Scientific Council comprised by prominent researchers. In addition to talks by Scientific Council members, the workshop includes invited talks by external experts in the research theme of the workshop. The 2011 workshop theme is Internet science with a focus on social networking.
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17 May
2011

Trade-offs in Implementing Atomic Multi-Writer, Multi-Reader Registers in Asynchronous Message-passing Systems

Dr. Chryssis Georgiou, Assistant Professor at Department of Computer Science, University of Cyprus
The technological advancement and information overload in recent years increased the popularity of Distributed Storage Systems where the data is replicated and maintained at multiple disks or servers residing at different network locations. While replication is sufficient to ensure data survivability, it raises an important question: "How can we efficiently maintain consistency among the replicas, despite system asynchrony and failures?"    
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