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IEEE 802.11ad: Directional 60 GHz Communication for Multi-Gigabit-per-Second Wi-Fi
No full textWith the ratification of the IEEE 802.11ad amendment to the 802.11 standard in December 2012, a major step has been taken to bring consumer wireless communication to the millimeter wave (mm-Wave) band. However, multi-Gbps throughput and small interference footprint come at the price of adverse signal propagation characteristics and require a fundamental rethinking of Wi-Fi communication principles. This paper describes the design assumptions taken into consideration for the IEEE 802.11ad standard and the novel techniques defined to overcome the challenges of mm-Wave communication. In particular we study the transition from omni-directional to highly directional communication and its impact on the design of IEEE 802.11ad.pu
A Successful Learning Experience using SPOCs
Get PDFThe application of MOOC technologies to on campus training, i.e. Small Private Online Courses (SPOCs), is a promising direction. Universidad Carlos III de Madrid has implemented several SPOCs during the last two years for first year students that need to review concepts about Physics, Mathematics or Chemistry. The Khan Academy platform was used for this purpose: Lecturers created a series of videos and exercises and the students interacted by watching those videos, solving the exercises and setting goals or earning badges and energy points. Students were able to interact with the SPOCs within the Khan Academy platform during one month. Next, students attended face-to-face lessons for one week about the mentioned subjects.TRUEpu
Rule-based detection of emotions in the Khan Academy platform
Get PDFThe current relevance of Massive Open Online
Courses (MOOCs) has provoked researchers in educational technology to work towards improving their pedagogical outcomes. Adaptive MOOCs are an example within this context. Given the importance of affective information within the adaptive systems, we propose a set of models to detect four emotions known to correlate with learning gains. The implementation of the models and the initial results from its application in a case study dataset are also provided.TRUEpu
GreenDCN: a General Framework for Achieving Network Energy Efficiency in Data Centers
No full textThe popularization of cloud computing has raised concerns over the energy consumption that takes place in data centers. In addition to the energy consumed by servers, the
energy consumed by large numbers of network devices emerges
as a significant problem. Existing work on energy-efficient data center networking primarily focuses on traffic engineering, which is usually adapted from traditional networks. We propose a new framework to embrace the new opportunities brought by combining some special features of data centers with traffic engineering. Based on this framework, we characterize the problem of achieving energy efficiency with a time-aware model, and we prove its NP-hardness with a solution that has two steps. First, we solve the problem of assigning virtual machines (VM) to servers to reduce the amount of traffic and to generate favorable conditions for traffic engineering. The solution reached for this problem is based on three essential principles that we propose. Second, we reduce the number of active switches and balance traffic flows, depending on the relation between power consumption and routing, to achieve energy conservation. Experimental results confirm that, by using this framework, we can achieve up to 50 percent energy savings. We also provide a comprehensive discussion on the scalability and practicability of the framework.pu
JAM: A Tabu-based Two-Stage Simulated Annealing Algorithm for the Multidimensional Arrangement Problem
Get PDFIn this paper we study a version of the Multidimensional Arrangement Problem (MAP) that embeds a graph into a multidimensional array minimizing the aggregated (Manhattan) distance of the embedded edges. This problem includes the minimum Linear Arrangement Problem (minLA) as a special case, among others. We propose JAM, a tabu-based two-stage simulated annealing heuristic for this problem. Our algorithm relies on existing techniques for the minimum linear arrangement (minLA) problem, which are non-trivially adapted to work in multiple dimensions. Due to the scarcity of specific benchmarks for MAP, we have tested the performance of our algorithm with benchmarks for the minLA and Quadratic Assignment Problems (with more than 80 graphs). For each graph in these benchmarks, we provide results for 1, 2 and 3-dimensional instances of MAP, enlarging, hence, the benchmarking resources for the research community. The results obtained show the practicality of JAM, often matching the best known result and even improving some of them.TRUEpu
Modeling D2D communications with LTE and WiFi
Get PDFIn this work we propose a roadmap towards the analytical understanding of Device-to-Device (D2D) communications in LTE-A networks. Various D2D solutions have been proposed, which include inband and outband D2D transmission modes, each of which exhibits different pros and cons in terms of complexity, interference, and spectral efficiency achieved. We go beyond traditional mode optimization and mode-selection schemes. Specifically, we formulate a general problem for the joint per-user mode selection, connection activation and resource scheduling of connections using both LTE and WiFi resources.pu
5G Communications: A Thousand Times More Network Capacity
No full texthttp://www.networks.imdea.org/whats-new/events/2014/5g-communications-thousand-times-more-network-capacityTRUEpu