Etapas de Rf/Fi de un sistema de 3ª generación Umts con antenas adaptativas

The technology of smart or adaptive antennas for mobile communications has received enormous interest worldwide in recent years. The purpose of this article is to give an overview of the RF/FI subsystem of a node B designed with adaptive antennas. The design must be done in order to pass all the specifications that 3gpp indicates for this system. This paper presents the basic structure of transmition and reception RF modules. A short explanation of the principal characteristics is introduced and the general structure of the modules is viewed

Diseño de amplificadores diferenciales de bajo ruido para antenas uwb en la banda baja del proyecto Ska

Differential amplifiers can be an appropriate solution in the implementation of radio astronomy receivers, due to their efficient interference and harmonic isolation. In this paper, two different topologies are presented. The first one consists of two single ended amplifiers in a balanced topology. The second one is formed by cascading two simple differential stages. Both circuits operate in the 300MHz to 1GHz bandwidth. Firstly, gain and noise characterizations of each amplifier have been done. Lastly, noise analysis of the whole reception system, formed by the antenna and the differential amplifiers, is presented

Diseño y Caracterización de un Array Activo de Banda Ancha para Radioastronomía

The Square Kilometre Array (SKA) radio-telescope will become a reality in 2020. Nowadays, many research groups are validating the technologies that will be necessary to build this enormous instrument. In order to cover the bandwidth between 70 MHz and 10 GHz, different antenna array designs and configurations will be used. This paper presents the design and characterization of a planar aperture array based on bunny-ear antennas, whose design is proposed to cover the midfrequency range of the telescope (from 300 to 1000 MHz). One of the main advantages of the present solution is its fully differential nature, which avoids the use of passive baluns, although it requires some especial considerations during the design and measurement processes

Broadband active differential array for the mid-frequency SKA band

This paper presents the design and characterization process of an active array demonstrator for the mid-frequency range (i.e., 300 MHz-1000 MHz) of the future Square Kilometre Array (SKA) radio telescope. This demonstrator, called FIDA3 (FG-IGN: Fundación General Instituto Geográfico Nacional - Differential Active Antenna Array), is part of the Spanish contribution for the SKA project. The main advantages provided by this design include the use of a dielectric-free structure, and the use of a fully-differential receiver in which differential low-noise amplifiers (LNAs) are directly connected to the balanced tapered-slot antennas (TSAs). First, the radiating structure and the differential low-noise amplifiers were separately designed and measured, obtaining good results (antenna elements with low voltage standing-wave ratios, array scanning capabilities up to 45°, and noise temperatures better than 52 K with low-noise amplifiers at room temperature). The potential problems due to the differential nature of the proposed solution are discussed, so some effective methods to overcome such limitations are proposed. Second, the complete active antenna array receiving system was assembled, and a 1 m2 active antenna array tile was characterized

Measurement procedures for an adaptive antenna system: application to WCDMA

Adaptive type smart antennas have not been implemented yet on the deployed UMTS systems, although UTRA-UMTS preview their operation and they also could improve capacity especially in a multiservice environment. This paper describes a set of novel measurement techniques that must be performed to evaluate the correct operation of a smart antenna system. The paper also describes the measurements carried out on a UMTS smart antenna prototype

Design and construction of a planar and cylindrical antenna measurement system at Polytechnique University of Madrid

Design And Construction of a Planar And Cylindrical Antenna Measurement System at Polytechnique University of Madri

Human-Centric multimodal machine learning: recent advances and testbed on AI-based recruitment

The presence of decision-making algorithms in society is rapidly increasing nowadays, while concerns about their transparency and the possibility of these algorithms becoming new sources of discrimination are arising. There is a certain consensus about the need to develop AI applications with a Human-Centric approach. Human-Centric Machine Learning needs to be developed based on four main requirements: (i) utility and social good; (ii) privacy and data ownership; (iii) transparency and accountability; and (iv) fairness in AI-driven decision-making processes. All these four Human-Centric requirements are closely related to each other. With the aim of studying how current multimodal algorithms based on heterogeneous sources of information are affected by sensitive elements and inner biases in the data, we propose a fictitious case study focused on automated recruitment: FairCVtest. We train automatic recruitment algorithms using a set of multimodal synthetic profiles including image, text, and structured data, which are consciously scored with gender and racial biases. FairCVtest shows the capacity of the Artificial Intelligence (AI) behind automatic recruitment tools built this way (a common practice in many other application scenarios beyond recruitment) to extract sensitive information from unstructured data and exploit it in combination to data biases in undesirable (unfair) ways. We present an overview of recent works developing techniques capable of removing sensitive information and biases from the decision-making process of deep learning architectures, as well as commonly used databases for fairness research in AI. We demonstrate how learning approaches developed to guarantee privacy in latent spaces can lead to unbiased and fair automatic decision-making process. Our methodology and results show how to generate fairer AI-based tools in general, and in particular fairer automated recruitment systemsThis work has received funding from different projects, including BBforTAI (PID2021-127641OB-I00 MICINN/FEDER), HumanCAIC (TED2021-131787B-I00), TRESPASS-ETN (MSCA-ITN-2019-860813), and PRIMA (MSCA-ITN-2019-860315). The work of A. Peña is currently supported by a FPU Fellowship (FPU21/00535) by the Spanish MIU and was supported by Madrid Government (PRICIT(2020/00334/001)) during the elaboration of this work. Also, I. Serna is supported by a FPI Fellowship from the UA