7,997 research outputs found

    Multifrequency and multifunction antennas based on single printed technology partially filled with metamaterial structures

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    The Radiofrequency Group from the Escuela Politécnica Superior of the Carlos III University from Madrid have been working in printed antennas for a long time. Recently the new technology of metamaterials has opened new possibilities in the development of multifrequency antennas with different radiation patterns to be used simultaneously for several applications (i.e. different mobile services and GPS or Galileo

    Two-Layered Superposition of Broadcast/Multicast and Unicast Signals in Multiuser OFDMA Systems

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    We study optimal delivery strategies of one common and KK independent messages from a source to multiple users in wireless environments. In particular, two-layered superposition of broadcast/multicast and unicast signals is considered in a downlink multiuser OFDMA system. In the literature and industry, the two-layer superposition is often considered as a pragmatic approach to make a compromise between the simple but suboptimal orthogonal multiplexing (OM) and the optimal but complex fully-layered non-orthogonal multiplexing. In this work, we show that only two-layers are necessary to achieve the maximum sum-rate when the common message has higher priority than the KK individual unicast messages, and OM cannot be sum-rate optimal in general. We develop an algorithm that finds the optimal power allocation over the two-layers and across the OFDMA radio resources in static channels and a class of fading channels. Two main use-cases are considered: i) Multicast and unicast multiplexing when KK users with uplink capabilities request both common and independent messages, and ii) broadcast and unicast multiplexing when the common message targets receive-only devices and KK users with uplink capabilities additionally request independent messages. Finally, we develop a transceiver design for broadcast/multicast and unicast superposition transmission based on LTE-A-Pro physical layer and show with numerical evaluations in mobile environments with multipath propagation that the capacity improvements can be translated into significant practical performance gains compared to the orthogonal schemes in the 3GPP specifications. We also analyze the impact of real channel estimation and show that significant gains in terms of spectral efficiency or coverage area are still available even with estimation errors and imperfect interference cancellation for the two-layered superposition system

    Ingeniería UC3M: de la formación a la profesionalización

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    El pasado 12 de mayo, el Parque Científico de la UC3M recibió a Álvaro Giménez, director de Ciencia y Exploración Robótica de la Agencia Espacial Europea (ESA) y director de esta agencia en España. Este encuentro refleja, una vez más, la relación de la UC3M con organismos y empresas, nacionales e internacionales, líderes en el terreno de la ingeniería. La Escuela Politécnica Superior de la UC3M nació con la aspiración de convertirse en uno de los mejores centros universitarios europeos en ingeniería y con el objetivo de contribuir a la mejora de la sociedad

    Antenas multifrecuencia y multifunción basadas en tecnología impresa simple parcialmente rellenas con estructuras metamateriales

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    El grupo de Radiofrecuencia de la Escuela Politécnica Superior de la Universidad Carlos III de Madrid lleva desarrollando desde hace muchos años antenas basadas en tecnología impresa. Los llamados metamateriales han abierto nuevas posibilidades en el desarrollo de los parches convencionales: antenas de múltiple frecuencia, diversos diagramas de radiación diferentes para abordar simultáneamente aplicaciones diferentes (i.e. antenas para dos servicios móviles diferentes y GPS o GALILEO)

    Espacio en la utopía. Providencia y panoptismo

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    El autor plantea una consideración “panóptica” de la Historia, a partir de la cual se abre a la Utopía y la Providencia realizada en el “verum-factum” de VicoThe author considers a “panoptical” consideration of History, which would open the possibility of Utopia and Providence, through Vico’s “verum-factum”

    Management of a LTE radio access network through orchestration platforms

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    This project propose a functional free software option for the implementation and optimization of a Radio Access Network (RAN) focused on a pedagogical purpose to the students can understand the 5G technology. The software called RAN Simulator it is the one selected with this propose due to the capability and option to communicate with ONAP Software which is in the future the software selected to operate Virtual Network Functions (VNF) and Physical Network Functions (PNF). This project has used to optimize a proposal of new carrier add on Long Term Evolution (LTE) which can be described as a new 5G network, this with the tools provided by RAN Simulator which it is capable to analyze and help to avoid and correct issues in a real RAN related to Physical Cell Identification (PCI). The effect of improve a network with this kind of tool can be seeing in the Key Performance Indicators (KPI), where drop calls, errors during hand over, and missing information sent to and from the user equipment can be improved and avoided, this with the immediate effect of offer better service to the users and improve the network. Understand, operate and get conclusions of the RAN Simulator software will be helpful to implement in operating networks and with the option of communication with ONAP, the ONAP software will be a complete option for operators due to the possibility of improvement and implement changes to the network
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