1,720,956 research outputs found
Analysis and Design of Bidirectional Integrated Transceivers for 5G Communication Systems
No full text5G communication systems promise to revolutionize the wireless communication world by allowing higher speed links with reduced latency. This improved performance is required by internet of things (IoT) applications where many devices share information with each other. The spectrum allocation is quite crowed in the low GHz frequency ranges and it can not sustain a similar data flow. The new 5G standard explores new frequency ranges, in particular the mmWave spectrum, to improve link capacity.
In the last decade, both industries and research institutes put a lot of efforts in the developement of the infrastructure network working at these operating frequencies. New challenges such as wide modulation bandwidth, beam-forming ad massive MIMO have attracted the attention of the scientific community. In particular, the adoption of mmWave frequency moves towards the realization of fully integrated beam-forming systems.
This works belongs to this research field by investigating new architectural solutions and circuit topologies. Ultra-scaled CMOS is the enabling technology in this field because it allows large scale production of 5G devices with restrained costs.
The Ph.D activity focus on the investigation of main integrated building blocks of beam-forming systems. The common feature of all the architectures illustrated in this work is the bidirectionality. This feature, along with blocks reuse, enables the realization of compact fully integrated systems. In transceivers front-end, the bidirectionally starts from the sharing of the antenna between the receiver and the transmitter.
This design challenge is addressed in chapter 2, where the realization of a compact T/R antenna switch is presented. The modulation process allows the propagation of electromagnetic waves in the mmWave spectrum. Up/down converters deal with the frequency translation of modulated signal. In this field, chapter 3 presents the design of a fully bidirectional up/down converter which translates the 5G mmWave range into a fixed low GHz intermediate frequency. The up/down converter rely on an image reject architecture where 90° hybrid couplers provide the necessary quadrature phase shifting. Chapter 4 analyzes the performance degradation due to lossy components in lumped element hybrid coupler realizations. To overcome also these undesired effects, a novel calibration and compensation technique is also proposed. The effectiveness of the introduced technique is demonstrated by its implementation in the up/down converter of chapter 3. The last building block, which deals with bidirectionality, is the phase shifter whose design is illustrated in chapter 5. For this purpose, a novel technique which exploits high order passive networks to implement the phase shifting is illustrated.5G communication systems promise to revolutionize the wireless communication world by allowing higher speed links with reduced latency. This improved performance is required by internet of things (IoT) applications where many devices share information with each other. The spectrum allocation is quite crowed in the low GHz frequency ranges and it can not sustain a similar data flow. The new 5G standard explores new frequency ranges, in particular the mmWave spectrum, to improve link capacity.
In the last decade, both industries and research institutes put a lot of efforts in the developement of the infrastructure network working at these operating frequencies. New challenges such as wide modulation bandwidth, beam-forming ad massive MIMO have attracted the attention of the scientific community. In particular, the adoption of mmWave frequency moves towards the realization of fully integrated beam-forming systems.
This works belongs to this research field by investigating new architectural solutions and circuit topologies. Ultra-scaled CMOS is the enabling technology in this field because it allows large scale production of 5G devices with restrained costs.
The Ph.D activity focus on the investigation of main integrated building blocks of beam-forming systems. The common feature of all the architectures illustrated in this work is the bidirectionality. This feature, along with blocks reuse, enables the realization of compact fully integrated systems. In transceivers front-end, the bidirectionally starts from the sharing of the antenna between the receiver and the transmitter.
This design challenge is addressed in chapter 2, where the realization of a compact T/R antenna switch is presented. The modulation process allows the propagation of electromagnetic waves in the mmWave spectrum. Up/down converters deal with the frequency translation of modulated signal. In this field, chapter 3 presents the design of a fully bidirectional up/down converter which translates the 5G mmWave range into a fixed low GHz intermediate frequency. The up/down converter rely on an image reject architecture where 90° hybrid couplers provide the necessary quadrature phase shifting. Chapter 4 analyzes the performance degradation due to lossy components in lumped element hybrid coupler realizations. To overcome also these undesired effects, a novel calibration and compensation technique is also proposed. The effectiveness of the introduced technique is demonstrated by its implementation in the up/down converter of chapter 3. The last building block, which deals with bidirectionality, is the phase shifter whose design is illustrated in chapter 5. For this purpose, a novel technique which exploits high order passive networks to implement the phase shifting is illustrated
A 24 GHz Quadrature VCO Based on Coupled PLL with -134 dBc/Hz Phase Noise at 10 MHz Offset in 28 nm CMOS
No full text
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
