1,720,957 research outputs found
Comparative Performance of Non-linear Distortion Effects in OFDM-RoF Link
No full textRecently, the integration of Orthogonal Frequency Division Multiplexing (OFDM) and Radio over Fiber (RoF) technique emerged the possibility of cost-effective and high data rate ubiquitous wireless networks. However, the nonlinear effects can severely degrade the performance of RoF as well as OFDM system. In this paper, the performance of OFDM-based RoF link with Mach-Zehnder modulator nonlinearity effects have been analyzed and simulated and then compared with single-carrier modulation case. Later, offset biased pre-distortion technique is applied in the OFDM-RoF link to produce a pre-distorted Mach-Zehnder modulator input voltage. Simulation results showed important observations in terms of distortion-free dynamic range and Signal to Noise Ratio (SNR) for the applied offset biased predistortion technique
On The Non-linear Distortion Effects in an OFDM-RoF Link
No full textRadio over Fiber (RoF) system is a promising technique for microcell and picocell applications for deployment of future ubiquitous wireless data networks. However, the performance of RoF systems can be severely degraded due to non-linear effects in the channel. Also, Orthogonal Frequency Division Multiplexing (OFDM), as a standard for broadband wireless networks, is being proposed for deployment with RoF systems to facilitate the total performance of a system. In this research, at first, the performance of OFDM-based RoF link with Mach-Zehnder modulator distortion effects has been analyzed at 5.8 GHz. Evaluation of mean-squared error of the proposed OFDM-RoF system was carried out to compare with the conventional single carrier system based RoF link after the modulator distortion case and also for fixed Signal to Noise Ratio (SNR) of 20 dB using undistorted OFDM signal. Later, nominal and offset biasing pre-distortion techniques are applied in proposed system to linearize the OFDM-RoF link. Thus, finally a comparison between the aforementioned pre-distortion techniques applied showed important observation in terms of distortion-free dynamic range and SNR to choose offset pre-distortion technique for our proposed system
Next Generation Converged Connectivity Model for Rural Business Opportunities in Developing Countries
No full textNext generation wireless technology with converged voice and data applications can offer rural connectivity for proper boost in Information and Communication Technology (ICT). In this study, a cost-effective ICT based solution for economic development of rural community in developing countries using appropriate next generation wireless networking technology has been represented. In the target country, Bangladesh, several Wireless Rural Points (WRPs) in a village will be connected to the local server of the village called Wireless Access Point (WAP). Each of several WAPs will be connected to several Rural Resource Servers (RRSs) and thus will form a Rural Resource Network (RRN). Adopting the proposed model with the existing ICT infrastructure of the target country can provide significant economic development therefore for the rural community. A similar implementation in other developing countries can offer a massive success
Next Generation Rural Wireless Connectivity Model For Developing Countries
No full textNext generation wireless technology with converged voice and data applications can offer rural connectivity for proper boost in Information and Communication Technology (ICT). In this study, a cost-effective ICT based solution for economic development of rural community in developing countries using appropriate next generation wireless networking technology has been represented. In the target country, Bangladesh, several Wireless Rural Points (WRPs) in a village will be connected to the local server of the village called Wireless Access Point (WAP). Each of several WAPs will be connected to several Rural Resource Servers (RRSs) and thus will form a Rural Resource Network (RRN). Adopting the proposed model with the existing ICT infrastructure of the target country can provide significant economic development therefore for the rural community. A similar implementation in other developing countries can offer a massive success
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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