Event Category: External Presentation (IN Speaker)

Keynote: Millimeter-Wave Joint Communication and Sensing

The high bandwidth available at millimeter-wave frequencies allows for very high data rates, and at the same time enables highly...

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Novel machine learning techniques to improve the forecasting of stroke postinterventive outcomes

Strokes are acute medical conditions in which poor blood flow to a part of the brain results in neuronal death....

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Try IT! Congress

IMDEA Networks will participate in the Try IT! congress organized by DA-ETSIINF in collaboration with ACM-UPM and the ETSI Informáticos...

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BASICS: Scheduling Base Stations to Mitigate Interferences in Cellular Networks

The increasing demand for higher data rates in cellular network results in increasing network density. As a consequence, inter-cell interference is becoming the most serious obstacle towards spectral efficiency. Therefore, considering that radio resources are limited and expensive, new techniques are required for efficient radio resource allocation in next generation cellular networks. In this paper, we propose a pure frequency reuse 1 scheme based on base station scheduling rather than the commonly adopted user scheduling. In particular, we formulate a base station scheduling problem to determine which base stations can be scheduled to simultaneously transmit, without causing excessive interference to any user of any of the scheduled base stations. We show that finding the optimal base station scheduling is NP-hard, and formulate the BASICS (BAse Station Inter-Cell Scheduling) algorithm, a novel heuristic to approximate the optimal solution at low complexity cost. The proposed algorithm is in line with the ABSF (almost blank sub-frame) technique recently standardized at the 3GPP. By means of numerical and packet-level simulations, we prove the effectiveness and superiority of BASICS as compared to the state of the art of inter-cell interference mitigation schemes.

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On the Compound Impact of Opportunistic Scheduling and D2D Communications in Cellular Networks

Opportunistic scheduling was initially proposed to exploit user channel diversity for network capacity enhancement. However, the achievable gain of opportunistic schedulers is generally restrained due to fairness considerations which impose a tradeoff between fairness and throughput. In this paper, we show via analysis and numerical simulations that opportunistic scheduling not only increases network throughput dramatically, but also increases energy efficiency and can be fair to the users when they cooperate, in particular by using D2D communications. We propose to leverage smartphone's dual-radio interface capabilities to form clusters among mobile users. We design simple, scalable and energy-efficient D2D-assisted opportunistic strategies, which would incentivize mobile users to form clusters. We use a coalitional game theory approach to analyze the cluster formation mechanism, and show that proportional fair-based intra-cluster payoff distribution brings significant incentive to all mobile users regardless of their channel quality.

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Distance-biased Sampling of Networks

Sampling a large network with a given distribution has been identified as a useful operation to build network overlays. For example, constructing small world network topologies can be done by sampling with a probability that depends on the distance to a given node. In this talk we describe algorithms that can be used by a source node to randomly select a node in a network with probability distributions that depend on their distance.

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Insomnia in the Access or How to Curb Access Network Related Energy Consumption

Access networks include modems, home gateways, and DSL Access Multiplexers (DSLAMs), and are responsible for 70-80% of total network-based energyconsumption. In this paper I'll take an in-depth look at the problem of greeningaccess networks, identify three root problems, and propose practical solutionsfor their user- and ISP-parts. On the user side, the combination of  continuous light traffic and lack of alternative paths condemnsgateways to being powered most of the time despite having Sleep-on-Idle (SoI) capabilities.

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Brief Announcement: B-Neck - A Distributed and Quiescent Max-min Fair Algorithm

In this brief announcement we propose B-Neck, a max-min fair distributed algorithm that is also quiescent. As far as we know, B-Neck is the first max-min fair distributed algorithm that does not require a continuous injection of control traffic to compute the rates. When changes occur, affected sessions are asynchronously informed, so they can start the process of computing their new rate (i.e., sessions do not need to poll the network for changes). The correctness of B-Neck is formally proved, and extensive simulations are conducted. In them it is shown that B-Neck converges relatively fast and behaves nicely in presence of sessions arriving and de- parting.

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Bounds on QoS-Constrained Energy Savings in Cellular Access Networks with Sleep Modes

Sleep modes are emerging as a promising technique for energy-efficient networking: by adequately putting to sleep and waking up network resources according to traffic demands, proportionality between energy consumption and network utilization can be approached, with important reductions in energy consumption. Previous studies have investigated and evaluated sleep modes for wireless access networks, computing variable percentages of energy savings.

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Shaping and designing cellular systems

The objective of this course is to learn how to model cellular systems for the use in optimizing the design of this type of network. The course will consist of the following parts:

  • A revision of basic queueing models
  • Analysis of cellular systems with a single cell
  • Channel reservation strategies possibility for the design of systems that optimize performance whilst minimizing the probability of interrupting current sessions
  • Models and algorithms to support the different priorities of existing users
  • Flow guarantees to different users through models of service differentiation
  • Hierarchical cellular structures

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