1,720,987 research outputs found
Dimensioning and capacity evaluation of UMTS networks by means of system simulation tools
No full textMobile radio network planning makes extensive use of system simulators, which can be subdivided into two broad categories, namely static and dynamic tools.
Starting from an ideal, regular cell layout, we perform a preliminary analysis suitable to dimension system parameters such as base station power. Subsequently, we impose call admission and load control, and we determine system capacity and performance. All the work was done with a pair of tools, a fully dynamic simulator and a static tool obtained from it by disabling dynamic features, aiming to show the differences in the results that can be obtained with the two kinds of simulators.
This study may be extended in future to more complex, realistic scenarios
A performance analysis of PRMA considering speech/data traffic, co-channel interference and ARQ error recovery
No full textPRMA (packet reservation multiple access) is a multiple access protocol proposed for use in advanced TDM-based radio systems. While the basic properties of such a protocol are understood, a comprehensive analysis of the protocol performance under realistic operation conditions is missing. The authors consider aspects which are key to a comprehensive analysis, such as traffic source interference, mixture of services (voice and data) and ARQ (automatic repeat request) function
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
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
A new methodology for the identification of validity domains of prediction models in urban environment
No full textThe choice of a given propagation model has a major impact on the accuracy and effectiveness of cellular planning, especially in an urban environment, where a higher degree of detail is required. Rigorous models, such as those based on ray optics, are generally heavily time-consuming; furthermore, they are accurate only if high resolution data-bases (of buildings, land usage, etc.) are available, and the cost of these data-bases is increasingly affecting the operators' budget. Therefore, one should use them only in their "validity domain", i.e., the area where they are both reliable and necessary; using complex tools where it is not needed implies an overhead in terms of computation time and, above all, data-base cost. For this reason, increasing interest and effort are being devoted by operators, manufacturers, and system planners in general to determine the validity domains of propagation models in urban environment. In this paper we introduce a new methodology, based on objective indicators related to field strength statistics, to determine these domains
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