1,720,955 research outputs found
Design and Development of Code Division Multiple Access Techniques for Various Communications and Signal Processing Applications
No full textThe goal for the next generation of mobile communication systems is to seamlessly integratewide variety of communication services such as high speed data, video and multimediatraffic as well as voice signals and high data rates with low bandwidth.Further, communication systems are to be power efficient.The technology needed to tackle these challenges to make theseservices available is popularly known as Code Division Multiple Access technology which is being employed in Third Generation (3G) and Fourth Generation 4G communication systems. One ofthe most promising approaches to 3G and 4G systemsis to combine a Wideband Code Division MultipleAccess (WCDMA) air interface with the fixed network of Global System for Mobilecommunications also called as Group Service Mobile (GSM). The work carried out in this thesis is concerned with the design and development of Code Division Multiple Access techniques for various Communications and Signal processing applications. The statistical properties of Pseudo- Noise (PN) codes have also been thoroughly studied. Chaotic signals have been generated using novel techniques. The main focus has been given on Multi- carrier and Multiuser CDMA communication systems.
In a practical CDMA communication systems the transmitted signal is corrupted bymultiple access interference which is generated in a structured way rather than treating it asAdditive White Gaussian Noise (AWGN). The signal is further corrupted by AWGN at thefront end of the receiver; various techniques have been proposed in this thesis which exploits the characteristic properties of frequency selective channel like Rayleigh channel. The modeling of frequency selective channel has also been done. Beam forming and rake diversity combing has beenemployed.The bit error rate, correlation
and power spectral density properties have been investigated atthe receiving end to evolve the performance of the proposed techniques.
Spreading codes are widely employed in CDMA based communication systems and Signal Processing applications. Different techniques are being employed for the realization of PN codes. A novel spreading scheme for generation of PN- codes has been presented in this thesis. Performance evaluation of the non- linear PN code in terms of auto- correlation and cross- correlation properties has been evaluated and compared with conventional PN codes.
Fourth generation mobile communications are being designed to support very high speed services of 100 Mbs to 1Gbs. For such high speed data transmissions, the channel becomes severely frequency selective due to time dispersion and the same system is not sufficient since the channel is both space and frequency dependent. To reduce Multiple Access Interference (MAI) and data transmission losses, beam forming technique using Antenna Array based DS- CDMA to overcome above mentioned problems has been proposed in this thesis. The performance of the proposed technique has been verified by computing Bit Error Rate (BER)versus Signal to Noise Ratio (SNR) which is related to variance.
A new multi-user detection (MUD) technique has been proposed. In CDMA spreading is achieved by using long PN or other codes so as to achieve high processing gain to reduce the effect of jamming and multipath interference. However, high value of processing gain requires spreading code of large length. In the proposed technique a novel method has been proposed in which time domain spreading is achieved at two successive stages which results T x T spreading.
Modern wireless communication systems based on CDMA techniques operate in environments that are interference, bandwidth, and multi- path fading limited. In order to combat these effects, complex receiver structures, such as those using complicated synchronization structures, demodulators, multi- user detectors and RAKE processors are often used. A Parallel Interference Cancellation (PIC) based CDMA system over Multipath Rayleigh fading channel has been proposed in this thesis. The proposed detector estimates and subtracts out all of the MAI for each user in parallel.
Anovel Intermediate Frequency Hopping (IF- FH) Spread Spectrumtechnique for CDMA applications has been proposed and investigated. The proposed technique requires low speed frequency synthesizers and low power consumption as the whole system has been operated at intermediate frequency and consequently adds a new variant of frequency hopping spread spectrum called as Intermediate Frequency Hopping Spread Spectrum.
The new scheme for the generation of digitally controlled chaotic signal for spreading in CDMA applications has been proposed in thisthesis.
Chaotic Systems are dynamic systems which show complex behavior. One of the defining attributes of chaotic system is the sensitive dependence on initial conditions. Time series generated from chaotic systems are wide-band in nature and noise like in appearance. A chaotic based system Frequency Hopping Spread Spectrum for CDMA applications has been proposed in this thesis in which digital method has been used to generate the wide-band analog chaotic signal for signal spreading.
A Pseudo Noise (PN) code controlled chaotic signal generator using real time Frequency Hopping Spread Spectrum technique has also been proposed. The proposed technique has a capability to initialize the chaotic signal generator which is necessary for predicting the future value for an authorized receiver.
Some of the proposed schemes have been simulated using Matlab/Simulink simulation software for checking the efficacy and utility. The bit error rate and correlation properties have also been checked. Prototype hardware modules of some of the proposed schemes presented in this thesis have been developed for experimental investigation. The thesis concludes with a discussion over the results of the conducted work during the course of this research. Future scope of work in this thesis direction has been discussed. A bibliography of concerned literature consulted has also been presented
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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