1,720,970 research outputs found
A Utility-Based Approach for Adaptive QAM with Diversity and Ambiguous CSI
No full textAdaptive M -ary quadrature amplitude modulation
(M -QAM) with subset diversity (SSD) is a way to cope with
quality of service variations in small and large-scale fading chan-
nels. We consider a slow adaptive modulation (SAM) technique
that adapts the constellation size to the slow variation of the
channel due, for example, to shadowing. SAM technique is more
practical than fast adaptive modulation (FAM) techniques, that
require adaptation to fast fading variations, even if it has been
has been shown to provide substantial increase in throughput
with respect to fixed schemes while maintaining an acceptable
low bit error outage (BEO). In addition SAM is less complex
than FAM and requires a lower feedback rate to the transmitter.
Performance of adaptive modulation and SSD techniques are
affected by non-ideal channel estimation. Here, we propose an
analytical framework to evaluate spectral efficiency and BEO for
slow adaptive QAM with SSD and imperfect channel knowledge.
We propose a utility-based approach to SAM, which accounts
for the abovementioned CSI imperfections. Our utility-based
approach is relevant to the game-theoretic approach, in which a
particular strategy (the transmitted power and the modulation
constellation option) is chosen by the decision-making control-
unit of the transceiver as a response to the set of possible (however uncertain) channel conditions
Utility-Based QAM Adaptation with Diversity and Ambiguous CSI under Energy Constraints
No full textAdaptive M -ary quadrature amplitude modulation (M-QAM) with subset diversity is a way to cope with the quality of service variations in small and large-scale fading channels. We consider a pilot-assisted slow adaptive modulation (SAM) technique that adapts the constellation size and the pilots energy to slow variations of the channel due to shadowing. The SAM technique is less complex and requires a lower feedback rate with respect to fast adaptive modulation techniques. We present an analytical framework to evaluate the bit-error probability for pilot-asisted slow adaptive QAM with subset diversity and imperfect channel state information (CSI) together with a utility-based approach to SAM. It accounts for the imperfect CSI, and is related to the game-theoretic approach, in which a particular strategy (the pilots energy and the constellation signaling) is chosen as a response to the set of possible channel conditions
Degrees of freedom for energy savings in practical adaptive wireless systems
No full textWe present a new design concept for adaptive wireless communications with new trade-offs
between system performance and energy consumption. The system performance, in terms of
bit error rate, outage probability, and achieved
spectral efficiency, depends on constellation signaling, applied diversity, and channel estimation.
Resources dedicated to channel estimation and
feedback traffic contribute to the overall system
and network energy consumption, and the resulting CO2
emission. We cons ider the trade-offs
among different methodologies and parameters
toward an energy-efficient green communication
system design. Below, we discuss the degrees of
freedom in the design of communications systems with imperfect channel estimation and diversity, and investigate their energy saving
options. We present the case studies of single and multicarrier systems applying both margin adaptive and rate-adaptive pilot-assisted transmission
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
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
- …
