1,720,964 research outputs found
Ricean K-factor estimation in mobile communication systems
No full textWe propose an estimator for the Ricean K-factor which has applications in mobile communication systems. The estimator is based on the statistics of the instantaneous frequency (IF) of the received signal. Using simulations, we show that the proposed estimator is robust to shadowing and its mean-square error (MSE) is significantly lower than that of the envelope-based estimators
Mobile unit velocity estimation based on the instantaneous frequency of the received signal
No full textThis paper presents a new mobile station velocity estimator based on the first moment of the instantaneous frequency (IF) of the received signal. The effects of shadowing, additive noise, and scattering distribution on the proposed velocity estimator are analyzed. We show that, unlike velocity estimators based on the envelope and quadrature components of the received signal, the proposed estimator is robust to shadowing. We also prove that the performance of the IF-based estimator is only mildly affected by the presence of additive noise. Finally, by using simulations we show that the performance of the proposed IF-based estimator is superior to that of existing velocity estimators
Mobile unit velocity estimation in microcellular systems using the ZCR of the instantaneous frequency of the received signal
No full textThis paper presents a new estimator for the velocity of a mobile station in microcellular systems. The proposed estimator is based on the zero-crossing rate of the instantaneous frequency of the received signal. The effects of additive noise, scattering distribution, and shadowing on the proposed velocity estimator are analyzed. The IF-based velocity estimator outperforms the conventional estimators in the presence of shadowing
Estimation of the velocity of mobile units in micro-cellular systems using the instantaneous frequency of the received signals
No full textHandover processes in micro-cellular systems are more involved than in cellular systems. In particular, micro-cellular systems suffer from the so-called corner effect where line-of-sight between the mobile station and the base station is suddenly lost when the mobile rounds a corner. As a result, the received signal drops rapidly below threshold level and the call can be lost. It has been shown that, if an accurate estimation of the velocity of the mobile unit is available, the call can be rescued by applying short temporal window averaging on the received signal. Current methods for estimating the velocity of mobile units in micro-cellular systems are based on the level crossing rate of the envelope of the received signals. This paper presents a new velocity estimator based on the instantaneous frequency of the received signal. The performance of the proposed estimator is shown to be superior to that of the level crossing rate method. The average relative error of the proposed estimator is down to below 8% whereas that of the LCR method reaches 14%
Detection of Newborns' EEG Seizure Using Time-Frequency Divergence Measures
No full textA time-frequency approach for detecting seizure activities in newborns' electroencephalogram (EEG) data is proposed. The discrimination between seizure and non-seizure states is based on the time-frequency distance between the consequent segments in the EEG signal. Three different time-frequency measures and three different reduced time-frequency distributions are used. The proposed method is tested on the EEG data acquired from three neonates with ages ranging from two days to two weeks. The experimental results validate the suitability of the proposed method in automated newborns' seizure detection. The results show an average seizure detection rate of 96% and false alarm rate of 5%
A novel estimator for the velocity of a mobile station in a micro-cellular system
No full textIn this paper, a new estimator for the velocity of a mobile station in a micro-cellular system is proposed. The proposed estimator is based on the instantaneous frequency of the received signal at the mobile station antenna. The performance of the proposed estimator in the presence of shadowing, additive noise, and non-isotropic scattering is analyzed, and compared with that of the conventional zero crossing rate based velocity estimator. We show that, unlike conventional estimators, the proposed estimator is robust to shadowing and additive noise
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
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