1,721,308 research outputs found
Radio source localization in multipath channels using em lens assisted massive antennas arrays
No full textComparison of two baseline AoA estimation methods in a EM lens assisted MAA system
No full textThe fifth generation (5G) of wireless systems will implement new groundbreaking technologies, for instance, massive multiple-input-multiple-output (MIMO) transmission. Such systems, by deploying massive antennas array (MAA), can enhance the data communication performance as well as offer precise radio localization based on angle of arrival (AoA) estimation. This paper considers two baseline AoA estimation techniques, namely complex conjugate AoA estimation and sum-difference patterns, when used in the electromagnetic (EM) lens assisted MAA system. Due to the property of the EM lens to focus the received signal on a small subset of antennas, these schemes can be implemented in the MAA system with reduced computational complexity using a fully digital or a mixed analog-digital structure. The presented techniques estimate the AoA of a received signal by exploiting two elements of the focused subset of antennas and alleviate the need of using high-resolution algorithms which form the high dimensional covariance and eigenvalue decomposition matrices. The obtained simulation results are comparable to the conventional algorithms without lens, despite significantly reducing the overall system complexity
Localization based on angle of arrival in EM lens-focusing massive MIMO
No full textThis paper proposes a novel algorithm for user localization using the angle of arrival (AoA) concept. We propose to combine the electromagnetic (EM) lens with the massive multiple-input multiple-output (MIMO) antenna array at the base station (BS). EM lens have the advantage of focusing the signal power on a subset of antennas as a function of the AoA. Thus, the provide an opportunity to estimate the location of user more efficiently with reduced number of radio frequency (RF) chains and computational costs. The obtained numerical results have shown that the EM lens based massive MIMO is capable of providing better AoA estimation
Models of Knowledge Transfer for Sustainable Development
No full textSustainable development requires that distant organisations connect to one another and exchange knowledge. Online social networks have the potential to support these processes. It is however important to understand and model the processes of knowledge transfer that can effectively occur on the Internet. This paper explores recent literature with the purpose to highlight relevant formal approaches that can help to model and analyse the processes of inter-organisational knowledge transfer for sustainable development
EM lens-clustering based direction of arrival estimation in massive antenna systems
No full textDirection of arrival (DoA) estimation in the massive antenna systems with reduced hardware and signal processing complexity is a challenging task. To address the issue, this paper presents an approach to estimate the DoA in a large number of antennas system combined with an electromagnetic (EM) lens. An EM lens has the ability to focus the received signal energy as a function of the angle of arrival (AoA) to a small subset/area of the antenna array at the base station (BS). Thus, it helps to estimate the DoA efficiently while minimizing the number of radio frequency (RF) chains and the associated signal processing costs. Moreover, by defining a cluster over a group of closely spaced subsets, the computational efforts of the DoA estimation algorithm can be further reduced
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
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