Autoevaluación y evaluación entre iguales en una asignatura de redes de ordenadores

Con la llegada del EEES se ha fomentado el uso de la evaluación continuada como un ingrediente de la docencia de calidad que permite al alumno mantenerse puntualmente informado de su progreso en el proceso de aprendizaje. Este trabajo se centra en el uso de la autoevaluación y la evaluación entre iguales como base para conseguir esta evaluación continuada. En él detallamos la experiencia, durante los cursos 2008/09 y 2009/10, del uso de estas dos herramientas de aprendizaje en el contexto de una asignatura de redes de ordenadores de tercer curso de Ingeniería Técnica en Informática de Gestión.SUMMARY: The use of continuous assessment has been encouraged in the adaptation to the European Higher Education Area. It is considered an ingredient to the high quality teaching that allows the student to have a fast feedback of her/his learning progress. This work focuses in the use of self assessment and peer assessment as the basis for a continuous evaluation system. We detail our experience during the years 2008/09 and 2009/10 on using such teaching tools in the context of a subject on computer networks.Peer Reviewe

Detection and Mitigation of DoS and DDoS Attacks in IoT-Based Stateful SDN: An Experimental Approach

The expected advent of the Internet of Things (IoT) has triggered a large demand of embedded devices, which envisions the autonomous interaction of sensors and actuators while offering all sort of smart services. However, these IoT devices are limited in computation, storage, and network capacity, which makes them easy to hack and compromise. To achieve secure development of IoT, it is necessary to engineer scalable security solutions optimized for the IoT ecosystem. To this end, Software Defined Networking (SDN) is a promising paradigm that serves as a pillar in the fifth generation of mobile systems (5G) that could help to detect and mitigate Denial of Service (DoS) and Distributed DoS (DDoS) threats. In this work, we propose to experimentally evaluate an entropy-based solution to detect and mitigate DoS and DDoS attacks in IoT scenarios using a stateful SDN data plane. The obtained results demonstrate for the first time the effectiveness of this technique targeting real IoT data traffic.This research was funded by EU, European Regional Development Fund, and the regional government of Extremadura, Spain, grant number IB18003, the Spanish Ministry of Science, Innovation and Universities grant numbers TIN2016-75097-P, RTI2018-102002-A-I00, PEJ2018-003648-A and FEDER and Junta de Andalucía grant number B-TIC-402-UGR18

Designing problem-specific operators for solving the Cell Switch-Off problem in ultra-dense 5G networks with hybrid MOEAs

The massive deployment of base stations is one of the key pillars of the fifth generation (5G) of mobile communications. However, this network densification entails high energy consumption that must be addressed to enhance the sustainability of this industry. This work faces this problem from a multi-objective optimization perspective, in which both energy efficiency and quality of service criteria are taken into account. To do so, several newly problem-specific operators have been designed so as to engineer hybrid multi-objective evolutionary metaheuristics (MOEAs) that bring expert knowledge of the domain to the search of the algorithms. These hybrid approaches have been able to improve upon canonical versions of the algorithms, clearly showing the contributions of our approach. Furthermore, this paper tests the hypothesis that the hybridization using several of those problem-specific operators simultaneously can enhance the search of MOEAs that are endowed only with a single one.Funding for open access charge: Universidad de Málaga / CBUA This work has been partially funded by the Spanish Ministry of Science and Innovation via grant PID2020-112545RB-C54, by the European Union NextGenerationEU/PRTR under grants TED2021-131699B-I00 and TED2021-129938B-I00 (MCIN/AEI/10.13039/501100011033, FEDER) and the Andalusian PAIDI program with grants A-TIC-608-UGR20, P18.RT.4830, and PYC20-RE-012-UGR. The authors also thank the Supercomputing and Bioinformatics Center of the Universidad de Málaga, for providing its services and the Picasso supercomputer facilities to perform the experiments (http://www.scbi.uma.es/). Funding for open access charge: Universidad de Málaga/CBUA

Metaheurísticas híbridas para el problema del apagado de celdas en redes 5G

La densificación masiva de estaciones base (BS) es una de las tecnologías facilitadoras bien reconocidas por la literatura para el desarrollo de la quinta generación de redes de telecomunicaciones (5G). Su implementación, sin embargo, que requiere el despliegue de miles de BSs por km^2, está en claro conflicto con uno de los requisitos de diseño de este tipo de redes, que pretende tener un 90% menos de consumo energético que la actual cuarta generación. Una forma de reducir el coste de estas redes ultradensas consiste en apagar un subconjunto de BSs de forma que minimice su consumo energético pero, a su vez, se maximice la capacidad de la misma. Es, por tanto, un problema de optimización multi-objetivo. En este trabajo se propone un nuevo operador específico para el problema que es capaz de mejorar considerablemente la efectividad de varios algoritmos multiobjetivo. Para ello, se han realizado experimentos con 9 escenarios de diferentes niveles de densificación tanto de BSs como de usuarios que muestran un comportamiento consistente y efectivo independientemente del algoritmo e instancia abordada.Este trabajo ha sido financiado parcialmente por el Ministerio de Economía y Competitividad y los fondos FEDER con los proyectos TIN2016-75097-P, TIN2014-56494-C4-3-P, TIN2017-85727-C4-2-P y TEC2015-68752. Francisco Luna también agradece la ayuda de la Universidad de Málaga, Campus de Excelencia Internacional Andalucía Tech, y el proyecto PPIT.UMA.B12017/15 del I Plan Propio de Investigación y Transferencia

Optimization of massive connections in 5G networks for IoT

The expected traffic demands for the coming years requires a major technology development. Indeed, from 2017 to 2022, the global annual traffic growth is estimated to reach 220%. This annual growth leads in turn to an increase in the number of users connected to IP networks, going from 2.4 to 3.6 devices connected per person. Currently, 4G networks are capable of handling this load, but the irruption of the 5G breakthroughs, expected to be at full operation by 2020, is visible. However, 5G technologies may come along with a considerable power consumption if they are not devised properly. As a consequence, a key issue in the developing of these networks is to make them energetically sustainable. In this work, a preliminary study of the optimization of various aspects of the 5G system is presented. It addresses the configuration of the different basic parameters of the system and optimizes the power transmitted by the base stations to obtain simultaneous improvements in system capacity and its power consumption for a massive connections scenario. To the best of our knowledge, this is the very first time this type of 5G scenario is optimized with these two performance criteria.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Clustering and beamforming for efficient communication in wireless sensor networks

Energy efficiency is a critical issue for wireless sensor networks (WSNs) as sensor nodes have limited power availability. In order to address this issue, this paper tries to maximize the power efficiency in WSNs by means of the evaluation of WSN node networks and their performance when both clustering and antenna beamforming techniques are applied. In this work, four different scenarios are defined, each one considering different numbers of sensors: 50, 20, 10, five, and two nodes per scenario, and each scenario is randomly generated thirty times in order to statistically validate the results. For each experiment, two different target directions for transmission are taken into consideration in the optimization process (ɸ = 0º and Ɵ = 45º; ɸ = 45º, and Ɵ = 45º). Each scenario is evaluated for two different types of antennas, an ideal isotropic antenna and a conventional dipole one. In this set of experiments two types of WSN are evaluated: in the first one, all of the sensors have the same amount of power for communications purposes; in the second one, each sensor has a different amount of power for its communications purposes. The analyzed cases in this document are focused on 2D surface and 3D space for the node location. To the authors’ knowledge, this is the first time that beamforming and clustering are simultaneously applied to increase the network lifetime in WSNs.Gobierno de Extremadura y Fondos FEDER: Proyecto IB13113peerReviewe

Modos principales de oscilación de la precipitación peninsular

Ponencia presentada en: I Congreso de la Asociación Española de Climatología “La climatología española en los albores del siglo XXI”, celebrado en Barcelona del 1 al 3 de diciembre de 1999.[ES]El análisis de Patrones de Oscilación Principales de series de precipitación mensual acumulada filtrada entre 18 y 96 meses dio como resultados un modo complejo con un período de oscilación de 36 meses y un tiempo de amortiguamiento de 10 meses. Los resultados de este análisis produjeron errores menores que los obtenidos con un modelo de persistencia.[EN]Principal Oscillation Pattern analysis is applied to monthly filtered precipitation retaining all variance between 18 and 96 months. A complex mode with an oscillation period of 36 months and an e-folding time of 10 months is obtained. This analysis yields smaller errors than a persistence model do.La financiación para llevar a cabo este trabajo fue proporcionada por el proyecto CLI97-0341-C03-01

Sistema de predicción por conjuntos a corto plazo sobre la Península Ibérica y Baleares

A short-range ensemble precipitation forecast system has been constructed over the Iberian Peninsula and Balearics by means of the fifth-generation Pennsylvania State University-National Center for Atmospheric Research Model (MM5). The ensemble system onsists of ten members, each run with a different combination of two different initial conditions from global models, IFS-ECMWF and GFS-NCEP, and five different subgrid-scale physics configurations for one month period, October 2006. The mesoscale verification is made by using observational precipitation data of the Spanish Climatic Network. The created short-range ensemble shows high spread-skill correlation values for daily precipitation. However, the asymmetric shape of the rank histogram indicates some underdispersion, suggesting a biased behaviour. The Talagrand shows as well the underdispersive effect because of its asymmetric distribution. The Relative Operating Characteristic curve shows a very outstanding area indicating the good discrimination capacity. The reliability diagrams are also indicative of the good reliability of the forecasting system, depicting in general good agreement between forecast probability and the mean observed frequency. Because of that, the verification proves the usefulness of the forecasting system over the study area.This work has been partially supported by the research projects CGL2007- 61328/CLI and UE Safewind G.A. No. 213740

Influence of North Atlantic teleconnection patterns over springtime precipitation in the Western Mediterranean

La influencia de los patrones de teleconexión de variabilidad de baja frecuencia en el Atlántico norte sobre la precipitación primaveral en el área del Mediterráneo occidental es investigada por medio de un análisis de descomposición en valores singulares (SVD). El análisis SVD de los valores mensuales de altura geopotencial en el nivel de 300 hPa y la precipitación mensual acumulada ha mostrado que la covariabilidad de los campos está dominada por dos patrones de circulación atmosférica. El primer modo está asociado al patrón de teleconexión conocido como EA-Jet y relaciona anomalías positivas de precipitación con situaciones de bloqueo alta-sobre-baja caracterizadas por la presencia de un flujo que se divide alrededor de una zona de altas presiones situadas al norte de las Islas Británicas y una zona de bajas presiones sobre la Península Ibérica. El segundo modo de covariabilidad tiene en cuenta la respuesta de la precipitación al patrón de la Oscilación del Atlántico Norte (NAO). Una situación de NAO positiva (negativa) está asociada a anomalías de precipitación positivas (negativas) sobre el sur (norte) del Mediterráneo occidental. Con estos dos modos, la variabilidad de los patrones atmosféricos a gran escala en el Atlántico Norte explican alrededor del 50% de la varianza de la precipitación primaveral en el Mediterráneo occidental. La significancia estadística de los modos y, por ende, de la respuesta de la precipitación a los patrones de teleconexión es investigada utilizando simulaciones de Monte Carlo