85 research outputs found

    Common Radio Resource Management Strategies for Quality of Service Support in Heterogeneous Wireless Networks

    Full text link
    Hoy en día existen varias tecnologías que coexisten en una misma zona formando un sistema heterogéneo. Además, este hecho se espera que se vuelva más acentuado con todas las nuevas tecnologías que se están estandarizando actualmente. Hasta ahora, generalmente son los usuarios los que eligen la tecnología a la que se van a conectar, ya sea configurando sus terminales o usando terminales distintos. Sin embargo, esta solución es incapaz de aprovechar al máximo todos los recursos. Para ello es necesario un nuevo conjunto de estrategias. Estas estrategias deben gestionar los recursos radioeléctricos conjuntamente y asegurar la satisfacción de la calidad de servicio de los usuarios. Siguiendo esta idea, esta Tesis propone dos nuevos algoritmos. El primero es un algoritmo de asignación dinámica de recusos conjunto (JDRA) capaz de asignar recursos a usuarios y de distribuir usuarios entre tecnologías al mismo tiempo. El algoritmo está formulado en términos de un problema de optimización multi-objetivo que se resuelve usando redes neuronales de Hopfield (HNNs). Las HNNs son interesantes ya que se supone que pueden alcanzar soluciones sub-óptimas en cortos periodos de tiempo. Sin embargo, implementaciones reales de las HNNs en ordenadores pierden esta rápida respuesta. Por ello, en esta Tesis se analizan las causas y se estudian posibles mejoras. El segundo algoritmo es un algoritmo de control de admisión conjunto (JCAC) que admite y rechaza usuarios teniendo en cuenta todas las tecnologías al mismo tiempo. La principal diferencia con otros algorimos propuestos es que éstos últimos toman las dicisiones de admisión en cada tecnología por separado. Por ello, se necesita de algún mecanismo para seleccionar la tecnología a la que los usuarios se van a conectar. Por el contrario, la técnica propuesta en esta Tesis es capaz de tomar decisiones en todo el sistema heterogéneo. Por lo tanto, los usuarios no se enlazan con ninguna tecnología antes de ser admitidos.Calabuig Soler, D. (2010). Common Radio Resource Management Strategies for Quality of Service Support in Heterogeneous Wireless Networks [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7348Palanci

    Optimum Transmission Through the Multiple-Antenna Gaussian Multiple Access Channel

    Full text link
    "(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works."[EN] This paper studies the optimal points in the capacity region of Gaussian multiple access channels (GMACs) with constant fading, multiple antennas, and various power constraints. The points of interest maximize general rate objectives that arise in practical communication scenarios. Achieving these points constitutes the task of jointly optimizing the timesharing parameters, the input covariance matrices, and the order of decoding used by the successive interference cancellation receiver. To approach this problem, Carathéodory s theorem is invoked to represent time-sharing and decoding orders jointly as a finite-dimensional matrix variable. This variable enables us to use variational inequalities to extend results pertaining to problems with linear rate objectives to more general, potentially nonconvex, problems, and to obtain a necessary and sufficient condition for the optimality of the transmission parameters in a wide range of problems. Using the insights gained from this condition, we develop and analyze the convergence of an algorithm for solving, otherwise daunting, GMAC-based optimization problems.D. Calabuig was supported by Marie Curie International Outgoing Fellowship within the European Commission, Research Executive Agency, through the COMIC Project under Grant 253990. R. H. Gohary and H. Yanikomeroglu were supported in part by Huawei Canada Company, Ltd., and in part by the Ontario Ministry of Economic Development and Innovations within the Ontario Research Fund through the Research Excellence Program. This paper was presented at the 2013 IEEE International Symposium on Information Theory and the 2014 IEEE International Workshop on Signal Processing Advances in Wireless Communications.Calabuig Soler, D.; Gohary, RH.; Yanikomeroglu, H. (2016). Optimum Transmission Through the Multiple-Antenna Gaussian Multiple Access Channel. IEEE Transactions on Information Theory. 62(1):230-243. https://doi.org/10.1109/TIT.2015.2502244S23024362

    Key Enabling Technologies for 5G: Millimeter-Wave and Massive MIMO

    Full text link
    [EN] 5G wireless networks are expected to operate with orders of magnitude higher performance than the current 4G deployments. The demand for 5000 times higher data rates leads to the necessity of finding new techniques to increase spectral efficiency and of exploring new frequency bands above 6 GHz. It has been proved that from UHF up to C band, a significant increase in system spectral efficiency can be reached through various techniques, such as Coordinated Multi-Point (CoMP), Massive Multiple-Input-Multiple-Output (MIMO), and interference management and cancellation; still, the resulting performance will not cope with the full expectations of IMT-2020 and 5G-PPP requirements for 5G networks, mainly in terms of offering 10 Gbps peak data rates with connection densities of 100 k¿1 M devices/km2. To overcome this limitation, the future architecture of such 5G networks is being defined to be deployed on small cells and to use higher frequency bands, such as super high frequency (SHF, 3¿30 GHz) or extremely high frequency (EHF, 30¿300 GHz), also referred as to centimeter and millimeter wave bands, respectively.Cardona Marcet, N.; Correia, LM.; Calabuig Soler, D. (2017). Key Enabling Technologies for 5G: Millimeter-Wave and Massive MIMO. International Journal of Wireless Information Networks. 24(3):201-203. doi:10.1007/s10776-017-0366-zS20120324

    Influence of brand image of a sports event on the recommendation of its participants

    Get PDF
    The aim of this research is to test the psychometric properties and relationships of a model where, from brand congruence of a sport event, trust and commitment to it can be generated, influencing future behavior of participants and resulting in a higher recommendation also called Word of Mouth (hereinafter WOM). A quantitative approach has been carried out by means of a validated questionnaire with Likert-type responses, and data were analyzed with the EQS 6.4 software. The findings indicated that the model is adequate, and also confirm that from congruence, we can explain, at a theoretical level, 45% of trust, and in the same way, from the congruence and trust, we can explain 67% of the commitment with the brand. Finally, it is confirmed that trust and brand commitment significantly influence WOM, predicting it up to 51%. These conclusions provide implications to managers, to guide their marketing strategies more effectively and to know what is important to achieve the desired behaviors, which will favor the sustainability of the event and the generation of positive impacts in the host location. This research also provides original information in a context such as sporting events where the study of brand image is practically non-existent

    Fairness-Driven Fast Resource Allocation for Interference-Free Heterogeneous Networks

    Full text link
    Resource allocation in heterogeneous wireless networks is a complex problem. This letter addresses this problem maximizing the sum of logarithms of received rates. From this function, and using the Karush-Kuhn-Tucker (KKT) conditions, this paper proposes an iterative algorithm for allocating resources, which is much faster than conventional techniques. This fast response can be used to optimize larger regions, getting closer to the performance of global and centralized algorithms. © 2012 IEEE.This work was supported by a Marie Curie International Outgoing Fellowship of the European Commission under the project COMIC.Calabuig Soler, D.; Monserrat Del Río, JF.; Cardona Marcet, N. (2012). Fairness-Driven Fast Resource Allocation for Interference-Free Heterogeneous Networks. IEEE Communications Letters. 16(7):1092-1095. doi:10.1109/LCOMM.2012.051512.120720S1092109516

    Percepción social de la importancia, el impacto y los beneficios esperados de la celebración de los Juegos Mediterráneos de Tarragona en 2017

    Get PDF
    The purpose of this study was to analyse the evolution between 2009 and 2010 of residents of Tarragona's perceptions of the importance, impact and expected benefits of hosting the 2017 Mediterranean Games in Tarragona. A questionnaire was administered to two random samples of residents of Tarragona one year apart. The results showed high percentages of people who felt that this sporting event is either quite important or very important from an economic, social and sporting perspective and that it also has a high local and regional impact, albeit not so much at a national or international level. The residents felt that hosting the Mediterranean Games in Tarragona would be quite a benefit to almost all areas that are influential in a city's development (infrastructure, tourism, the economy, employment, sports and sports facilities), in addition to the advantages for political groups, athletes, and the organizing committee. The evolution of the two samples was negative for most aspects included in the survey. Lower means and percentages were observed in the 'quite' and 'a lot' categories for the 2010 sample. The results of this study are useful for events organizers in developing strategies to improve citizens' involvement, participation and identification with events.La finalidad de este estudio fue analizar la evolución entre los años 2009 y 2010 en la percepción de los tarraconenses sobre el grado de importancia, el impacto y los beneficios esperados de la celebración de los Juegos Mediterráneos de Tarragona en 2017. Se recogieron dos muestras de ciudadanos con un año de diferencia. Los resultados mostraron porcentajes elevados de personas que consideraban que este evento deportivo tiene bastante o mucha importancia económica, social y deportiva, así como una elevada repercusión a nivel local y autonómico, aunque no tan relevante a nivel estatal e internacional. Los tarraconenses consideraron que casi todas las áreas o sectores que influyen en el desarrollo de la ciudad (infraestructuras, turismo, economía, ocupación, práctica deportiva e instalaciones deportivas), los grupos políticos, los deportistas y el comité organizador se beneficiarían bastante o mucho de la celebración de los Juegos Mediterráneos en su ciudad. Asimismo la evolución entre las dos muestras fue negativa para la mayoría de aspectos consultados, observándose medias y porcentajes inferiores en las categorías de bastante y mucho para la muestra de 2010. Los resultados de este estudio son útiles a los organizadores del evento para desarrollar estrategias que permitan mejorar la implicación, participación e identificación de los ciudadanos con el evento.A finalidade deste estudo foi analisar a evolução entre os anos 2009 e 2010 na percepção dos tarraconenses sobre o grau de importância, impacto e benefícios expectáveis da celebração dos Jogos Mediterrâneos de Tarragona em 2017. Foram recolhidas duas amostras de cidadãos com um ano de diferença. Os resultados revelaram percentagens elevadas de pessoas que consideravam que este evento desportivo tem bastante ou muita importância económica, social e desportiva, assim como uma elevada repercussão a nível local e na comunidade autónoma, embora não tão relevante a nível estatal e internacional. Os tarraconenses consideraram quase todas as áreas ou sectores que influem no desenvolvimento da cidade (infraestruturas, turismo, economia, ocupação, prática desportiva e instalações desportivas), os grupos políticos, os desportistas e o comité organizador beneficiariam bastante ou muito da celebração dos Jogos Mediterrâneos na sua cidade. Contudo, a evolução entre as duas amostras foi negativa para a maioria dos aspectos analisados, observando-se médias e percentagens inferiores nas categorias bastante e muito para a amostra de 2010. Os resultados deste estudo são úteis aos organizadores do evento para que possam desenvolver estratégias que permitam melhorar a implicação, participação e identificação dos cidadãos com o evento

    Configurable node density generation with application to hotspot modelling

    Full text link
    Mobility models are very relevant mainly when studying the performance of wireless systems by means of computer simulations. The main problem arises when deciding the best mobility model for a particular application. In some cases, it is very important to emulate hotspots or, in general, zones with different user (or node) densities. Current models do not allow complete control over hotspots, or in other words, they do not allow any general node density to be defined in the simulation area. Usually, when hotspots are modelled, closed zones are created with different numbers of users in each area, thus ensuring a fixed node density in each area. However, this approach results in an unfair comparison among users since they cannot move across zones. This paper proposes a new mechanism to solve these drawbacks. Using this mechanism, any general node density can be emulated allowing nodes to move around the entire simulation area. Any mobility model can be applied together with this density control mechanism, provided that the mobility model ensures a uniform node distribution. © 2010 Elsevier Ltd.This work has been funded by the Spanish Ministry of Science and Innovation under project TEC2008-06817-C02-01/TEC.Calabuig Soler, D.; Monserrat Del Río, JF.; Cardona Marcet, N. (2011). Configurable node density generation with application to hotspot modelling. Mathematical and Computer Modelling. 53(11-12):2229-2237. https://doi.org/10.1016/j.mcm.2010.08.028S222922375311-1

    Análisis sobre el grado de conocimiento e identificación de los tarraconenses con la candidatura a los Juegos Mediterráneos de Tarragona en 2017

    Get PDF
    El objetivo de este estudio fue analizar la evolución entre los años 2009 y 2010 en el grado de conocimiento e identificación de los tarraconenses con la candidatura a los Juegos Mediterráneos de Tarragona en 2017. Se recogieron las opiniones de dos muestras de ciudadanos con un año de diferencia (N = 246 para 2009 y N = 307 para 2010). Los resultados mostraron una evolución positiva de un año a otro en aspectos como el conocimiento sobre lo que son los Juegos Mediterráneos, el grado de información recibida, el grado con el que se identifica la sociedad con este evento deportivo, el grado de dificultad percibida en la organización del mismo, el grado de preparación de la ciudad en servicios como la sanidad, los alojamientos y la restauración, el grado de coordinación entre las administraciones públicas o el trabajo realizado por la candidatura. No obstante, una gran parte de los ciudadanos no consideraban que la ciudad estuviese bastante o muy preparada en otras áreas como el transporte público o las instalaciones deportivas, observándose una evolución negativa entre los dos años en los accesos desde el exterior y en los servicios de limpieza y de seguridad. Los resultados de este estudio pueden ayudar a mejorar la implicación y participación de la ciudadanía en este tipo de acontecimientos deportivos

    On the Integration of Grassmannian Constellations into LTE Networks: a Link-level Performance Study

    Get PDF
    This paper presents Grassmannian signaling as a transmission scheme that can be integrated in Long Term Evolution (LTE) to support higher user speeds and to increase the throughput achievable in the high Signal to Noise Ratio (SNR) regime. This signaling is compared, under realistic channel assumptions, with the diversity transmission modes standardized in LTE, in particular, Space-Frequency Block Coding and Frequency-Switched Transmit Diversity for two and four transmit antennas, respectively. In high-speed scenarios, and even with high antenna correlation, Grassmannian signaling outperforms the LTE diversity transmission modes starting from four transmit antennas. Furthermore, in the high SNR regime, Grassmannian signaling can increase the link data rate up to 10% and 15% for two and four antennas, respectively

    Embryo culture in presence of oviductal fluid induces DNA methylation changes in bovine blastocysts

    Get PDF
    During the transit through the oviduct, the early embryo initiates an extensive DNA methylation reprogramming of its genome. Given that these epigenetic modifications are susceptible to environmental factors, components present in the oviductal milieu could affect the DNA methylation marks of the developing embryo. The aim of this study was to examine if culture of bovine embryos with oviductal fluid (OF) can induce DNA methylation changes at specific genomic regions in the resulting blastocysts. In vitro produced zygotes were cultured in medium with 3 mg/mL bovine serum albumin (BSA) or 1.25% OF added at the one- to 16-cell stage (OF1-16), one- to 8-cell stage (OF1-8) or 8- to 16-cell stage (OF8-16), and then were cultured until Day 8 in medium with 3 mg/mL BSA. Genomic regions in four developmentally important genes (MTERF2, ABCA7, OLFM1, GMDS) and within LINE-1 retrotransposons were selected for methylation analysis by bisulfite sequencing on Day 7-8 blastocysts. Blastocysts derived from OF1-16 group showed lower CpG methylation levels in MTERF2 and ABCA7 compared with the BSA group. However, CpG sites within MTERF2, ABCA7 and OLFM1 showed higher methylation levels in groups OF1-8 and OF8-16 than in OF1-16. For LINE-1 elements, higher CpG methylation levels were observed in blastocysts from the OF1-16 group than in the other experimental groups. In correlation with the methylation changes observed, mRNA expression level of MTERF2 was increased, while LINE-1 showed a decreased expression in blastocysts from OF1-16 group. Our results suggest that embryos show transient sensitivity to OF at early stages, which is reflected by specific methylation changes at the blastocyst stage.Fil: Barrera, Antonio Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Garcia, Elina Vanesa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Investigaciones Biológicas. Universidad Nacional de Tucumán. Instituto Superior de Investigaciones Biológicas; ArgentinaFil: Hamdi, Meriem. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; EspañaFil: Sánchez Calabuig, María Jesús. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; EspañaFil: López Cardona, Ángela Patricia. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; EspañaFil: Fonseca Balvís, Noelia. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; EspañaFil: Rizos, Dimitrios. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; EspañaFil: Gutiérrez Adan, Alfonso. Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. Departamento de Reproducción Animal; Españ
    corecore