On Security and Quality of Service in Multihop Wireless Networks Mobile Ad hoc Networks, Wireless Mesh Networks and Wireless Sensor Networks have attracted remarkable attention in the research community in recent years. Fashioned from whatever devices are immediately available, the self-organizing nature of these networks promises spontaneous, untethered communication in absence of infrastructure, or the organic growth of wireless meshed networks. However, the fact that ad hoc and mesh networks are not yetdeployed at large indicates that they are not ready for prime time. This talk discusses selected issues in the area of quality of service and security for multihop wireless networks. We start with an overview on the work carried out at the Mobile Networking & Ubiquitous Communications group at Technische Universität Darmstadt, Germany.

​Many emerging scientific and industrial applications require transferring multiple terabytes of data on a daily basis. Examples include pushing scientific datasets from particle accelerators/colliders to laboratories around the world, synchronizing data centers in different continents, and replicating collections of high definition videos from Olympic Games, taking Location on a different time-zone. A convenient property of all above applications is their ability to tolerate delivery delays from a few hours to a few days. Such Delay-Tolerant Bulk (DTB) transfers are currently being serviced through the postal system using hard drives and DVDs, or through expensive dedicated networks.

JTP: An Energy-conscious Transport Protocol for Ad Hoc Networks Energy consciousness is percolating rapidly through all areas of research for technologies that are power driven. In the context of networking, the area of ad hoc networks has been the main driving factor pushing energy-related research, with significant efforts pursued mainly at the physical, data-link and routing layers of the protocol stack.

With the Internet offering a single best-effort service, there have been numerous proposals of diversified network services that align better with the divergent needs of different distributed applications. The failure of these innovative architectures to gain wide deployment is primarily due to economic and legacy issues, rather than technical shortcomings. We propose a new paradigm for network service differentiation where design principles account explicitly for the multiplicity of Internet service providers and users as well as their economic interests in environments with partly deployed new services. Our key idea is to base the service differentiation on performance itself, rather than price. 

In the last decade, a new theoretical foundation for quantitative network research has emerged. Its key ingredients are the following: economic models to formulate network resource allocation as a convex optimization problem; use of optimization methods to devise decentralized solutions to these problems, in terms of dynamic adaptation of the relevant variables; tools of control theory to understand the dynamic properties of these methods. The resulting body of theory has been highly successful in providing models for TCP congestion control, describing how local protocols should be designed to allow for interesting global properties to emerge. From here, recent research has advanced this methodology to other layers of the protocol stack. In this course we will provide an introduction to this interdisciplinary field of research.

We study the impact of policies to associate users with base stations/access points on flow-level performance in interference limited wireless networks.
Most research in this area has used static interference models (i.e., neighboring base stations are always active) and resorted to intuitive objectives such as load balancing. In this paper, we show that this can be counter productive, and that asymmetries in load can lead to significantly better performance in the presence of dynamic interference which couples the transmission rates experienced by users at various base stations. We propose a methodology that can be used to optimize the performance of a class of coupled systems, and apply it to study the user association problem. We show that by properly inducing load asymmetries, substantial performance gains can be achieved relative to a load balancing policy (e.g., 15 times reduction in mean delay). We present a novel measurement based, interference-aware association policy that infers the degree of interference induced coupling and adapts to it.

"ADSL is becoming the standard form of residential and small-business broadband access to the Internet due, primarily, to its low deployment cost. These ADSL residential lines are often deployed with Access Points (AP) that provide wireless connectivity. While the ADSL technology has showed evident limits in terms of capacity, the short-range wireless communication can guarantee a similar or higher capacity. Even more important, it is often possible for a residential wireless client to be in range of several other APs belonging to nearby neighbors with ADSL connections. We introduce ClubADSL, a prototype wireless station that can connect to several multi-frequency APs in range and aggregate their available ADSL bandwidth. ClubADSL achieves a fair bandwidth among the concurrent stations and minimizes the impact of end-to-end latency on the system performance. We show the feasibility of such a system in seamlessly transmitting TCP traffic, and validate its experimental implementation over commodity hardware in controlled scenarios."

This talk will present a brief overview of systems, technologies and applications that are part of Ambient Intelligence (AmI). It is also the purpose of this talk to bring together researchers for inspiring innovation in the evolution of AmI and for answering the question: What are the challenges we need to bet on?

Ponente: 
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Fecha: 08 Junio, 2009, a las 10:00
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The conference will be conducted in English
 

The peer-to-peer paradigm shows the potential to provide the same functionality like client/server based systems, but with much lower costs.

One substantial limitation of p2p systems are missing guarantees on the quality of service, as the whole infrastructure is based on unreliable peers. In order to control the quality of peer-to-peer systems, monitoring and management mechanisms need to be applied. Both tasks are challenging in large-scale networks with autonomous, unreliable nodes.