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

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

We study optimal delivery strategies of one common and $K$ 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 $K$ 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 $K$ 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 $K$ 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

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

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

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”

Toxicity of Agrochemicals on Freshwater Invertebrates — A Short Review

The increase of worldwide population and the need to control pests are some of the factors that have led to the application of agrochemicals on agricultural areas to protect and increase crop production. Nevertheless, these substances are of environmental concern since they can reach water reservoirs and act on non-target organisms. Therefore, different aquatic species have been tested to evaluate their sensitivity to different toxicants, including pesticides, so as to elucidate the secondary effects of these chemicals to estimate “safe levels” in aquatic media. A wide variety of toxicity tests can be found in literature to evaluate the toxicity of xenobiotics in the environment at organismal and sub-organismal levels under different regimes. This chapter focuses on those tests performed with some freshwater invertebrates (cladocerans and rotifers) to study the toxicity of four important classes of pesticides