On the Fictitious Play and Channel Selection Games

International audienceConsidering the interaction through mutual interference of the different radio devices, the channel selection (CS) problem in decentralized parallel multiple access channels can be modeled by strategic-form games. Here, we show that the CS problem is a potential game (PG) and thus the fictitious play (FP) converges to a Nash equilibrium (NE) either in pure or mixed strategies. Using a 2−player 2−channel game, it is shown that a convergence in mixed strategies might lead to cycles of action profiles which lead to individual spectral efficiencies (SE) which are worse than the SE at the worst NE in mixed and pure strategies. Finally, exploiting the fact that the CS problem is a PG and an aggregation game, we present a method to implement FP with milder information conditions than those required in its original version

CONTROL DE POTENCIA BASADO EN TEORÍA DE JUEGOS EN SISTEMAS DE COMUNICACIONES INALÁMbRICAS

Cada vez existen mayores exigencias en cuanto a la cobertura, capacidad y calidad de los servicios ofrecidos por los sistemas de comunicaciones móviles. Lo anterior exige a fabricantes y operadores la implementación de procedimientos de Gestión de Recursos Radio, que permitan hacer un uso eficiente de los recursos con los que cuenta una red. El artículo analiza la aplicación del control de potencia en una red de única portadora haciendo uso de la Teoría de Juegos (GT) y teoremas de inteligencia artificial como el Aprendizaje Reforzado (RL) para analizar aspectos relacionados a la cobertura y capacidad, asegurando la calidad de los servicios ofrecidos. PALABRAS CLAVES: Redes móviles, control de potencia, sistema limitado por interferencia, teoría de juegos

MITIGACIÓN DE LA INTERFERENCIA INTER-CELDA CON TÉCNICAS DE REÚSO DE FRECUENCIA EN UN SISTEMA LTE

En este artículo, se presentan los resultados obtenidos de la implementación y evaluación de un módulo de mitigación de interferencia inter-celda sobre un simulador básico a nivel de sistema para Evolución de Largo Término (LTE, Long Term Evolution); Se emplearon las técnicas Reúso de Frecuencia Suave y Reúso de Frecuencia Fraccional 1.5, para evaluar el desempeño del sistema y evidenciar la variación de la interferencia inter-celda. Los resultados muestran que el uso de estas técnicas mitiga la interferencia intercelda en diferentes condiciones.PALABRAS CLAVES: Reúso de frecuencia, Interferencia intercelda, Capacidad de LTE

Satisfaction with life and its relations with religion and health in Colombian university students

El presente estudio tuvo como objetivo estimar las correlaciones entre la satisfacción con la vida, la religión y la salud en una muestra de 446 participantes (42,60% varones y el 57,40% mujeres), con edades comprendidas entre los 18 a 69 años. Adicionalmente se llevó a cabo un análisis de regresión múltiple por pasos con el fin de conocer las variables predictoras de la satisfacción con la vida. Todos los participantes completaron los siguientes instrumentos: Cuestionario sociodemográfico, Escala de Satisfacción con la Vida, Cuestionario de Salud SF-36 y Escala de Religiosidad. A partir de los resultados se comprobó que la satisfacción con la vida no se asocia con la religión profesada. Mayor satisfacción con la vida fue predicha por mayor práctica religiosa organizacional, mejor salud general, mejor salud mental y mejor rol emocional. En definitiva, el nivel de satisfacción con la vida no parece estar relacionado con la religión profesada, aunque sí con la práctica de actividades que propone la institución religiosa de cada uno.The objective of the present study was to estimate the correlations between the satisfaction with life, religion and health in a sample of 446 participants (42,60% men and 57,40% women) between the ages of 18 to 69 years. In addition, an analysis of multiple regression by steps was made in order to determine the predictors of life satisfaction. All participants completed the following instruments: Sociodemographic Questionnaire, Satisfaction with Life Scales, SF-36 Questionnaire of Health and Scale of Religiosity. From the results it was found that the satisfaction with life was not associated with the religion professed. Greater satisfaction with life was predicted by greater organizational religious practice, better general health, better mental health and better emotional role. In conclusion the level of satisfaction with life does not seem to be related to the religion professed, but with the practice of activities proposed by the religious institution of each one

Effect of aliskiren on post-discharge outcomes among diabetic and non-diabetic patients hospitalized for heart failure: insights from the ASTRONAUT trial

Aims The objective of the Aliskiren Trial on Acute Heart Failure Outcomes (ASTRONAUT) was to determine whether aliskiren, a direct renin inhibitor, would improve post-discharge outcomes in patients with hospitalization for heart failure (HHF) with reduced ejection fraction. Pre-specified subgroup analyses suggested potential heterogeneity in post-discharge outcomes with aliskiren in patients with and without baseline diabetes mellitus (DM). Methods and results ASTRONAUT included 953 patients without DM (aliskiren 489; placebo 464) and 662 patients with DM (aliskiren 319; placebo 343) (as reported by study investigators). Study endpoints included the first occurrence of cardiovascular death or HHF within 6 and 12 months, all-cause death within 6 and 12 months, and change from baseline in N-terminal pro-B-type natriuretic peptide (NT-proBNP) at 1, 6, and 12 months. Data regarding risk of hyperkalaemia, renal impairment, and hypotension, and changes in additional serum biomarkers were collected. The effect of aliskiren on cardiovascular death or HHF within 6 months (primary endpoint) did not significantly differ by baseline DM status (P = 0.08 for interaction), but reached statistical significance at 12 months (non-DM: HR: 0.80, 95% CI: 0.64-0.99; DM: HR: 1.16, 95% CI: 0.91-1.47; P = 0.03 for interaction). Risk of 12-month all-cause death with aliskiren significantly differed by the presence of baseline DM (non-DM: HR: 0.69, 95% CI: 0.50-0.94; DM: HR: 1.64, 95% CI: 1.15-2.33; P < 0.01 for interaction). Among non-diabetics, aliskiren significantly reduced NT-proBNP through 6 months and plasma troponin I and aldosterone through 12 months, as compared to placebo. Among diabetic patients, aliskiren reduced plasma troponin I and aldosterone relative to placebo through 1 month only. There was a trend towards differing risk of post-baseline potassium ≥6 mmol/L with aliskiren by underlying DM status (non-DM: HR: 1.17, 95% CI: 0.71-1.93; DM: HR: 2.39, 95% CI: 1.30-4.42; P = 0.07 for interaction). Conclusion This pre-specified subgroup analysis from the ASTRONAUT trial generates the hypothesis that the addition of aliskiren to standard HHF therapy in non-diabetic patients is generally well-tolerated and improves post-discharge outcomes and biomarker profiles. In contrast, diabetic patients receiving aliskiren appear to have worse post-discharge outcomes. Future prospective investigations are needed to confirm potential benefits of renin inhibition in a large cohort of HHF patients without D

Retour de sortie de canal bruyant dans le canal d'interférence

In this thesis, the two-user Gaussian interference channel with noisy channel-output feedback (GIC-NOF) is studied from two perspectives: centralized and decentralized networks. From the perspective of centralized networks, the fundamental limits of the two-user GICNOF are characterized by the capacity region. One of the main contributions of this thesis is an approximation to within a constant number of bits of the capacity region of the two-user GIC-NOF. This result is obtained through the analysis of a simpler channel model, i.e., a two-user linear deterministic interference channel with noisy channel-output feedback (LDIC-NOF). The analysis to obtain the capacity region of the two-user LDIC-NOF provides the main insights required to analyze the two-user GIC-NOF. From the perspective of decentralized networks, the fundamental limits of the two-user decentralized GIC-NOF (D-GIC-NOF) are characterized by the η-Nash equilibrium (η-NE) region. Another contribution of this thesis is an approximation of the η-NE region of the two-user GIC-NOF, with η> 1. As in the centralized case, the two-user decentralized LDIC-NOF (D-LDIC-NOF) is studied first and the lessons learnt are applied in the two-user D-GIC-NOF. The final contribution of this thesis consists in a closed-form answer to the question: “When does channel-output feedback enlarge the capacity or η-NE regions of the two-user GIC-NOF or two-user D-GIC-NOF?”. This answer is of the form: Implementing channel-output feedback in transmitter-receiver i enlarges the capacity or η-NE regions if the feedback SNR is beyond SNRi* , with i ∈ {1, 2}. The approximate value of SNRi* is shown to be a function of all the other parameters of the two-user GIC-NOF or two-user D-GIC-NOF.Dans cette thèse, le canal Gaussien à interférence à deux utilisateurs avec voie de retour dégradée par un bruit additif (GIC-NOF) est étudié sous deux perspectives : les réseaux centralisés et décentralisés. Du point de vue des réseaux centralisés, les limites fondamentales du GIC-NOF sont caractérisées par la région de capacité. L’une des principales contributions de cette thèse est une approximation à un nombre constant de bits près de la région de capacité du GIC-NOF. Ce résultat est obtenu grâce à l’analyse d’un modèle de canal plus simple, le canal linéaire déterministe à interférence à deux utilisateurs avec voie de retour dégradée par un bruit additif (LDIC-NOF). L’analyse pour obtenir la région de capacité du LDIC-NOF fournit les idées principales pour l’analyse du GIC-NOF. Du point de vue des réseaux décentralisés, les limites fondamentales du GIC-NOF sont caractérisées par la région d’η-équilibre de Nash (η-EN). Une autre contribution de cette thèse est une approximation de la région η-EN du GIC-NOF, avec η > 1. Comme dans le cas centralisé, le cas décentralisé LDIC-NOF (D-LDIC-NOF) est étudié en premier et les observations sont appliquées dans le cas décentralisé GIC-NOF (D-GIC-NOF). La contribution finale de cette thèse répond à la question suivante : “À quelles conditions la voie de retour permet d’agrandir la région de capacité, la région η-EN du GIC-NOF ou du D-GIC-NOF ? ”. La réponse obtenue est de la forme : L’implémentation de la voie de retour de la sortie du canal dans l’émetteur-récepteur i agrandit la région de capacité ou la région η-EN si le rapport signal sur bruit de la voie de retour est supérieure à SNRi* , avec i ∈ {1, 2}. La valeur approximative de SNRi* est une fonction de tous les autres paramètres du GIC-NOF ou du D-GIC-NOF

Evaluación del desempeño de sistemas de comunicación móvil celular de tercera generación - WCDMA

Este trabajo de maestría profundizó en el conocimiento sobre el funcionamiento de sistemas basados en Acceso al Medio por División de Código (CDMA, Code Division Multiple Access) a nivel físico, se estudió y analizó la evolución y el desempeño a nivel de enlace de una de las tecnologías en comunicación móvil celular de tercera generación y se evaluó la capacidad de este tipo de sistemas por medio del modelado y la simulación. Este trabajo ha permitido y permitirá fortalecer los procesos de enseñanza y aprendizaje en la Facultad de Ingeniería Electrónica y Telecomunicaciones, permitiendo un acercamiento a las grandes investigaciones y desarrollos realizados por Universidad, Centros de Investigación y Laboratorios a nivel mundial.It was acquired with this project knowledge about the operation of systems based on Code Division Multiple Access (CDMA) at the physical level. It was studied and analyzed the evolution and performance in a link level one of the most important technologies in third generation mobile communications systems and it was evaluated its capacity through modeling and simulation. This work has allowed and will allow reinforcing the teaching and learning processes in the Electronics and Telecommunications Faculty, allowing being closer to the worldwide researches and developments in Universities, research centres and labs

On the Convergence of Fictitious Play in Channel Selection Games

International audienceConsidering the interaction through mutual interference of the different radio devices, the channel selection (CS) problem in decentralized parallel multiple access channels can be modeled by strategic-form games. Here, we show that the CS problem is a potential game (PG) and thus the fictitious play (FP) converges to a Nash equilibrium (NE) either in pure or mixed strategies. Using a 2−player 2−channel game, it is shown that a convergence in mixed strategies might lead to cycles of action profiles which lead to individual spectral efficiencies (SE) which are worse than the SE at the worst NE in mixed and pure strategies. Finally, exploiting the fact that the CS problem is a PG and an aggregation game, we present a method to implement FP with milder information conditions than those required in its original version

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Global economic burden of unmet surgical need for appendicitis

Background There is a substantial gap in provision of adequate surgical care in many low- and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially