Maximum likelihood estimation of position in GNSS

In this letter, we obtain the Maximum Likelihood Estimator of position in the framework of Global Navigation Satellite Systems. This theoretical result is the basis of a completely different approach to the positioning problem, in contrast to the conventional two-steps position estimation, consisting of estimating the synchronization parameters of the in-view satellites and then performing a position estimation with that information. To the authors’ knowledge, this is a novel approach which copes with signal fading and it mitigates multipath and jamming interferences. Besides, the concept of Position–based Synchronization is introduced, which states that synchronization parameters can be recovered from a user position estimation. We provide computer simulation results showing the robustness of the proposed approach in fading multipath channels. The Root Mean Square Error performance of the proposed algorithm is compared to those achieved with state-of-the-art synchronization techniques. A Sequential Monte–Carlo based method is used to deal with the multivariate optimization problem resulting from the ML solution in an iterative way.Peer Reviewe

ML estimator and hybrid beamformer for multipath and interference mitigation in GNSS receivers

This paper addresses the estimation of the code-phase(pseudorange) and the carrier-phase of the direct signal received from a direct-sequence spread-spectrum satellite transmitter. The signal is received by an antenna array in a scenario with interference and multipath propagation. These two effects are generally the limiting error sources in most high-precision positioning applications. A new estimator of the code- and carrier-phases is derived by using a simplified signal model and the maximum likelihood (ML) principle. The simplified model consists essentially of gathering all signals, except for the direct one, in a component with unknown spatial correlation. The estimator exploits the knowledge of the direction-of-arrival of the direct signal and is much simpler than other estimators derived under more detailed signal models. Moreover, we present an iterative algorithm, that is adequate for a practical implementation and explores an interesting link between the ML estimator and a hybrid beamformer. The mean squared error and bias of the new estimator are computed for a number of scenarios and compared with those of other methods. The presented estimator and the hybrid beamforming outperform the existing techniques of comparable complexity and attains, in many situations, the Cramér–Rao lower bound of the problem at hand.Peer Reviewe

COMalaWEB: plataforma basada en noves tecnologies aplicades a la docència

Les possibilitats que ens ofereixen les noves tecnologies de la informació aplicades a l’àmbit de la docència és un tema encara no prou ben explotat. Aquest projecte pretén investigar aquests conceptes mitjançant la creació d’una plataforma docent que aprofita la potencialitat de tecnologies tals com les bases de dades, l’estructuració de documents en XML, l’hipertext o la representació gràfica interactiva. A més, aquesta estructura s’ha farcit amb continguts docents de qualitat que cobreixen el temari de dues assignatures obligatòries al programa d’Enginyeria Superior de Telecomunicacions de la UPC. El procés d’aprenentatge es basa en la integració de petits conceptes sobre una base ja coneguda. La rigidesa d’un temari fix, o l’índex d’un llibre, forcen un seguiment lineal dels conceptes que sovint no és l’òptim ni per al professor ni per a l’alumne. COMalaWEB permet la consulta de diferents conceptes de forma no lineal, on l’usuari decideix quin nivell d’aprofundiment necessita, si vol més exemples, retornar a conceptes anteriors o anar a temes més avançats. Aquestes capacitats es complementen amb aplicacions d’autoavaluació i demostracions gràfiques interactives que reforcen la realimentació entre teoria i pràctica. La totalitat del programari desenvolupat per a la implementació d’aquesta plataforma i els continguts docents que presenta han estat publicats sota llicència pública per assegurar-ne la lliure distribució i accés, així com la protecció dels drets intel•lectuals

LaViCAD: Laboratorio Virtual de Comunicaciones Analógicas y Digitales

En este trabajo se presenta tanto el diseño como la experimentación de un Laboratorio Virtual de Comunicaciones Analógicas y Digitales: LaViCAD. Mediante LaViCAD se pueden experimentar y verificar diferentes aplicaciones correspondientes a estas temáticas, propias de un primer ciclo del currículum de ingeniería en telecomunicaciones. A nivel pedagógico, las ventajas que supone la utilización de un laboratorio virtual, pueden resumirse en facilitar el aprendizaje de determinadas materias, actuando como un enlace entre el modelo de conocimiento basado en conceptos y teorías y su comprensión práctica.Peer ReviewedPostprint (published version

Projecte COM@WEB: plataforma web d'aprenentatge intel•ligent de processament del Senyal i Comunicacions.

La plataforma d’e-learning: comweb.upc.edu és una eina multimèdia de suport a l’estudi, l’experimentació i l’adquisició de tècniques d’auto-aprenentatge. COM@WEB s’ofereix com a punt de trobada entre estudiants, professors i altres professionals relacionats amb el mon de les telecomunicacions i/o de la docència universitària. A la plataforma s’ha integrat el Laboratori Virtual per a Comunicacions Analògiques i Digitals (LaViCAD) com una eina interactiva de treball. Els usuaris principals als que va dirigit aquest projecte són els estudiants de telecomunicacions, molt especialment als que estan cursant assignatures de temàtiques de comunicacions i processament del senyal. Els continguts de la plataforma formen part d’una base de dades de recursos docents, entre els que hi ha: Documents de tipus text corresponents a part de la teoria, Exercicis d’aplicació resolts, Qüestionaris d’autoavaluació i simuladors de Java (aquestos últims corresponents a LaViCAD). Els diferents recursos s’ofereixen a través de la plataforma estructurats en diferents cursos i es relacionen entre sí gràcies a les seves metadades. Tots els recursos creats son de lliure accés i en resum la plataforma compleix les característiques de tenir una arquitectura oberta i extensible, facilitat d’ús per als usuaris: professors i estudiants i facilitat d’ampliació i de millora de la informació disponible de forma dinàmica

¿Qué es una intervención sanitaria eficiente en España en 2020?

Hace más de 15 años que en Gaceta Sanitaria se publicó el artículo titulado «¿Qué es una tecnología sanitaria eficiente en España?». El creciente interés por fijar el precio de las nuevas tecnologías en función del valor que estas proporcionan a los sistemas de salud y la experiencia acumulada por los países de nuestro entorno hacen oportuno revisar qué es una intervención sanitaria eficiente en España en el año 2020. El análisis de coste-efectividad sigue siendo el método de referencia para maximizar los resultados en salud de la sociedad con los recursos disponibles. La interpretación de sus resultados requiere establecer unos valores de referencia que sirvan de guía sobre lo que constituye un valor razonable para el sistema sanitario. Los umbrales de eficiencia deben ser flexibles y dinámicos, y actualizarse periódicamente. Su aplicación debe estar basada en la gradualidad y la transparencia, considerando, además, otros factores que reflejen las preferencias sociales. Aunque la fijación de los umbrales corresponde a los decisores políticos, en España puede ser razonable utilizar unos valores de referencia como punto de partida que podrían estar comprendidos entre los 25.000 y los 60.000 euros por año de vida ajustado por calidad. No obstante, en la actualidad, más que la determinación de las cifras exactas de dicho umbral, la cuestión clave es si el Sistema Nacional de Salud está preparado y dispuesto a implantar un modelo de pago basado en el valor, que contribuya a lograr la gradualidad en las decisiones de financiación y, sobre todo, a mejorar la previsibilidad, la consistencia y la transparencia del proceso.Fifteen years ago, Gaceta Sanitaria published the article entitled “What is an efficient health technology in Spain?” The growing interest in setting the price of new technologies based on the value they provide to health systems and the experience accumulated by the countries in our environment make it opportune to review what constitutes an efficient health intervention in Spain in 2020. Cost-effectiveness analysis continues to be the reference method to maximize social health outcomes with the available resources. The interpretation of its results requires establishing reference values that serve as a guide on what constitutes a reasonable value for the health care system. Efficiency thresholds must be flexible and dynamic, and they need to be updated periodically. Its application should be based on and transparency, and consider other factors that reflect social preferences. Although setting thresholds is down to political decision-makers, in Spain it could be reasonable to use thresholds of 25,000 and 60,000 Euros per QALY. However, currently, in addition to determining exactfigures for the threshold,the key question is whether the Spanish National Health System is able and willing to implement a payment model based on value, towards achieving gradual financing decisions and, above all, to improve the predictability, consistency and transparency of the process

Safety and vaccine-induced HIV-1 immune responses in healthy volunteers following a late MVA-B boost 4 years after the last immunization

Background: We have previously shown that an HIV vaccine regimen including three doses of HIV-modified vaccinia virus Ankara vector expressing HIV-1 antigens from clade B (MVA-B) was safe and elicited moderate and durable (1 year) T-cell and antibody responses in 75% and 95% of HIV-negative volunteers (n = 24), respectively (RISVAC02 study). Here, we describe the long-term durability of vaccine-induced responses and the safety and immunogenicity of an additional MVA-B boost. Methods: 13 volunteers from the RISVAC02 trial were recruited to receive a fourth dose of MVA-B 4 years after the last immunization. End-points were safety, cellular and humoral immune responses to HIV-1 and vector antigens assessed by ELISPOT, intracellular cytokine staining (ICS) and ELISA performed before and 2, 4 and 12 weeks after receiving the boost. Results: Volunteers reported 64 adverse events (AEs), although none was a vaccine-related serious AE. After 4 years from the 1st dose of the vaccine, only 2 volunteers maintained low HIV-specific T-cell responses. After the late MVA-B boost, a modest increase in IFN-γ T-cell responses, mainly directed against Env, was detected by ELISPOT in 5/13 (38%) volunteers. ICS confirmed similar results with 45% of volunteers showing that CD4+ T-cell responses were mainly directed against Env, whereas CD8+ T cell-responses were similarly distributed against Env, Gag and GPN. In terms of antibody responses, 23.1% of the vaccinees had detectable Env-specific binding antibodies 4 years after the last MVA-B immunization with a mean titer of 96.5. The late MVA-B boost significantly improved both the response rate (92.3%) and the magnitude of the systemic binding antibodies to gp120 (mean titer of 11460). HIV-1 neutralizing antibodies were also enhanced and detected in 77% of volunteers. Moreover, MVA vector-specific T cell and antibody responses were boosted in 80% and 100% of volunteers respectively. Conclusions: One boost of MVA-B four years after receiving 3 doses of the same vaccine was safe, induced moderate increases in HIV-specific T cell responses in 38% of volunteers but significantly boosted the binding and neutralizing antibody responses to HIV-1 and to the MVA vector

Adelante / Endavant

Séptimo desafío por la erradicación de la violencia contra las mujeres del Institut Universitari d’Estudis Feministes i de Gènere "Purificación Escribano" de la Universitat Jaume

Maximum likelihood estimation of position in GNSS

In this letter, we obtain the Maximum Likelihood Estimator of position in the framework of Global Navigation Satellite Systems. This theoretical result is the basis of a completely different approach to the positioning problem, in contrast to the conventional two-steps position estimation, consisting of estimating the synchronization parameters of the in-view satellites and then performing a position estimation with that information. To the authors’ knowledge, this is a novel approach which copes with signal fading and it mitigates multipath and jamming interferences. Besides, the concept of Position–based Synchronization is introduced, which states that synchronization parameters can be recovered from a user position estimation. We provide computer simulation results showing the robustness of the proposed approach in fading multipath channels. The Root Mean Square Error performance of the proposed algorithm is compared to those achieved with state-of-the-art synchronization techniques. A Sequential Monte–Carlo based method is used to deal with the multivariate optimization problem resulting from the ML solution in an iterative way.Peer Reviewe

ML estimator and hybrid beamformer for multipath and interference mitigation in GNSS receivers

This paper addresses the estimation of the code-phase(pseudorange) and the carrier-phase of the direct signal received from a direct-sequence spread-spectrum satellite transmitter. The signal is received by an antenna array in a scenario with interference and multipath propagation. These two effects are generally the limiting error sources in most high-precision positioning applications. A new estimator of the code- and carrier-phases is derived by using a simplified signal model and the maximum likelihood (ML) principle. The simplified model consists essentially of gathering all signals, except for the direct one, in a component with unknown spatial correlation. The estimator exploits the knowledge of the direction-of-arrival of the direct signal and is much simpler than other estimators derived under more detailed signal models. Moreover, we present an iterative algorithm, that is adequate for a practical implementation and explores an interesting link between the ML estimator and a hybrid beamformer. The mean squared error and bias of the new estimator are computed for a number of scenarios and compared with those of other methods. The presented estimator and the hybrid beamforming outperform the existing techniques of comparable complexity and attains, in many situations, the Cramér–Rao lower bound of the problem at hand.Peer Reviewe