1,720,963 research outputs found
Estudio comparativo de Calidad de Servicio utilizando simulación en una WLAN con el estándar IEEE 802.11e para tráfico de voz, video y datos
Full text linkEste proyecto tiene como objetivo comprobar la Calidad de Servicio utilizando el simulador de redes NS2, en una WLAN de Infraestructura de voz, video y datos con estándares IEEE 802.11g e IEEE 802.11e mediante los tipos de acceso EDCA (Enhanced Distributed Channel Access) y HCCA (Hybrid Coordination Function Controlled Access). Se abordan los conceptos referentes a WLANs IEEE 802.11, donde se analizan sus principales características, funcionamiento y arquitectura. Posteriormente se estudian las características, funcionamiento, formatos de tramas y procedimientos de acceso de los métodos EDCA y HCCA presentes en el estándar IEEE 802.11e. Se presentan las características utilizadas para los tráficos de voz, video y datos. Se ilustran los diferentes escenarios de simulación, con sus respectivas topologías físicas y distribuciones de estaciones inalámbricas. Finalmente se presentan, analizan y validan los resultados obtenidos de las simulaciones para cada escenario propuesto. Para lo cual se realizan estudios comparativos del funcionamiento de los métodos de acceso DCF (Distributed Coordination Function), EDCA y HCCA para cada tipo de tráfico, empleando métricas como velocidad de transmisión, retardo extremo a extremo y porcentaje de pérdida de paquetes. Adicionalmente se estudia el efecto de la variación de los parámetros EDCA: AIFSN, CWmin, CWmax y TXOPlimit.This project aims to test the Quality of Service using the NS2 network simulator, in an infrastructure WLAN for voice, video and data with IEEE 802.11g and IEEE 802.11e standards by the EDCA (Enhanced Distributed Channel Access) and HCCA (Hybrid Coordination Function Controlled Access) access types. The project describes the concepts relating to IEEE 802.11 WLANs, by analyzing its main features, operation and architecture. Subsequently, the features, operation, frame formats and procedures for EDCA and HCCA access methods, which are present in the IEEE 802.11e, are studied. The characteristics used for voice, video and data traffic are presented. The different simulation scenarios are illustrated with their physical topologies and distribution of wireless stations. Finally the project presents, validates and analyzes the results of simulations for each proposed scenario. In these scenarios, comparative studies are carried out to analyze the performance of DCF (Distributed Coordination Function), EDCA and HCCA methods access for each type of traffic, using metrics such as baud rate, end-to-end delay and packet loss rate. Furthermore, the effect of variation of the EDCA parameters, like AIFSN, CWmin, CWmax and TXOPlimit are studied.Hidalgo Lascano, Pablo Wilian, directo
Rate-Splitting Multiple Access for Cell-Free ISAC Massive MIMO systems
No full textpeer reviewedThis paper investigates rate-splitting multiple access (RSMA) in a cell-free massive multi-input multi-output (MIMO) system with integrated sensing and communication (ISAC). In this sytem model, we consider the maximization of the minimum rate subject to radar sensing constraints and a maximum power budget. A successive convex approximation based scheme is developed to solve the non-convex problem by optimizing the precoding vectors for radar and communication, as well as the common rate variables. Numerical results show the superior performance of the proposed RSMA method over conventional cell-free massive MIMO schemes under different scenarios with varying numbers of APs, antennas, and users
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
ACO-based Scheme in Edge Learning NOMA Networks for Task-Oriented Communications
Full text linkpeer reviewedConventional communications systems centered on data prioritize maximizing network throughput using Shannon’s theory, which is primarily concerned with securely transmitting the data despite limited radio resources. However, in the realm of edge learning, these methods frequently fall short because they depend on traditional source coding and channel coding principles, ultimately failing to improve learning performance. Consequently, it is crucial to transition from a data-centric viewpoint to a task-oriented communications approach in wireless system design. Therefore, in this paper, we propose efficient communications under a task-oriented principle by optimizing power allocation and edge learning-error prediction in an edge-aided non-orthogonal multiple access (NOMA) network. Furthermore, we propose a novel approach based on the ant colony optimization (ACO) algorithm to jointly minimize the learning error and optimize the power allocation variables. Moreover, we investigate four additional benchmark schemes (particle swarm optimization, quantum particle swarm optimization, cuckoo search, and butterfly optimization algorithms). Satisfactorily, simulation results validate the superiority of the ACO algorithm over the baseline schemes, achieving the best performance with less computation time. In addition, the integration of NOMA in the proposed task-oriented edge learning system obtains higher sum rate values than those achieved by conventional schemes.9. Industry, innovation and infrastructur
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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