1,721,174 research outputs found
A Transmission/Equalisation Procedure for Mobile Digital Radio Links using Interpolated Channel Estimates
No full textA transmission/equalisation strategy is proposed for frequency-selective, fast time-varying noisy digital channels. Each information data sequence is surrounded by a pair of training sequences of known symbols; these are employed by the receiver to estimate the channel impulse response (CIR) at the beginning and at the end of the timeslot, via a suitable Kalman-like filter with fast convergence properties. The CIR behavior along the data sequence is then linearly interpolated and exploited step-by-step by a maximum likelihood sequence equaliser (MLSE). A simple transmitter/receiver structure is then obtained and its performance analysed via computer simulations
Equalisation of Digital Radio Channels with large Multipath Delay for Cellular Land Mobile Applications
No full textA new maximum a posteriori (MAP) equalizer is
proposed for digital radio links affected by large multipath
delays. The “sparse” nature of the channel, where a few nonzero
powerful taps are spaced by many negligible taps, is exploited
to achieve a complexity proportional to the number of nonzero
taps. When the channel is time-varying, an efficient nonlinear
Kalman-like channel estimator is employed to track only the
nonzero tap
Multistage Symbol-by-Symbol Bayesian Interference Cancellation for CDMA Links Affected by Severe Multipath
No full textMAP Multiuser detection with Soft Interference cancellation for UMTS TD-CDMA Receivers
No full textA new multiuser detector (MUD) exploiting the MAP algorithm is proposed for channels affected by severe multipath and is then suitable for Time-Division Duplexing (TDD) CDMA receivers. After coherent combining the received multipaths, a multidimensional MAP nonlinearity is employed to compute step-by-step the A Posteriori Probabilities (APPs) of the transmitted data for each user separately and then their expected values conditional to the available observations. These are then employed for soft ISI and MAI removal from the received sequences so that the APPs can be more reliably re-computed. The procedure is iterated in a multistage structure until final decisions are taken. From the comparison with other existing techniques (interference cancellation, zero-forcing) the proposed Reduced MAP-MUD receiver exhibits better performance and equal or minor complexity
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
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