Sorry, this entry is only available in European Spanish.  Instructor:  Lugar:  Fecha: 12th May, 2009, 10:00 – 11:00 Organización:   

Some among the most widespread applications of the Internet (real-time streaming multimedia applications) are based on packet exchanges that assume a very low packet delay. In order to offer some form of better service to this kind of traffic some architectural frameworks have been proposed, in which traffic sources obey some form of constraints on the maximum number of packets sent in every time interval, in which traffic is subdivided into classes, and where at any node all packets are served taking only into account the class to which they belong to. For these networks an open issue is their stability, that is the possibility to derive finite bounds to packet delay and queue size at each node.

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.

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?

If you would like more information about Dr. Tiago Camilo, please visit his Linkedin profile: http://www.linkedin.com/in/tiagocamilo More information about Nokia Siemens 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.

A great deal of of interesting work was done in the 1970s in generalizing shortest path algorithms to a wide class of semirings also called "path algebras" or "dioids". Although the evolution of Internet Routing protocols does not seem to have taken much inspiration from this work, recent "reverse engineering" efforts have demonstrated that an algebraic approach is very useful for both understanding existing protocols and for exploring the design space of future Internet routing protocols. This course is intended teach participants the basic concepts needed to understand this approach. No previous background will be assumed. 

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.