1,721,000 research outputs found
Time-Power Multiplexing for LoRa-Based IoT Networks: An Effective Way to Boost LoRaWAN Network Capacity
No full textWhy is network reselection an issue for cross-border vehicular applications?
No full textSafety-critical advanced driver-assistance systems (ADAS) are expected to benefit from cellular vehicle-to-everything communication, providing both short-range and long-range wireless connectivity between vehicles and road/network infrastructure equipment. However, upon switching between adjacent coverage areas belonging to different network operators, the wireless connectivity may be discontinued. This issue prevents network service continuity and causes interruption of ADAS service availability. In this paper, we aim at assessing the average duration of service interruption due to such network reselection procedures. We provide performance evaluation results highlighting that there is a wide gap between the best case scenario and the worst case scenario. Moreover, we propose a simple heuristic to limit the downside of the lack of cooperation between network operators; our heuristic algorithm, which does not require a tight integration between the operators, performs much better than the worst case and it is fairly comparable with the best case scenario. Nevertheless the present work highlights the importance of a tighter integration between network operators to reduce the delay to the minimum
Channel-Quality Reporting Enabled by Machine Learning in Non-Stationary Environments
No full textIn this paper, we propose a novel channel quality reporting approach for cellular communication systems. The proposed approach features a differential coding scheme in stationary propagation conditions and a detector of non-stationary propagation conditions, which further triggers a channel-quality predictor for the non-stationary environment based on a machine learning method. In particular, the machine learning engine learns about the specific large variations of the channel quality by collecting signaling information from mobile terminals in a given region. Our simulations in a controlled urban environment with vehicular users show that the proposed solution can effectively replace the 4-bit channel-quality reporting scheme of LTE and NR standards with a 2-bit one, providing correct channel-quality indication in non-stationary conditions with high probability
Worldwide Connectivity for the Internet of Things Through LoRaWAN
Get PDFThe low-power wide-area network (LPWAN) paradigm is gradually gaining market acceptance. In particular, three prominent LPWAN technologies are emerging at the moment: LoRaWAN™ and SigFox™, which operate on unlicensed frequency bands, and NB-IoT, operating on licensed frequency bands. This paper deals with LoRaWAN™, and has the aim of describing a particularly interesting feature provided by the latest LoRaWAN™ specification—often neglected in the literature—i.e., the roaming capability between different operators of LoRaWAN™ networks, across the same country or even different countries. Recalling that LoRaWAN™ devices do not have a subscriber identification module (SIM) like cellular network terminals, at a first glance the implementation of roaming in LoRaWAN™ networks could seem intricate. The contribution of this paper consists in explaining the principles behind the implementation of a global LoRaWAN network, with particular focus on how to cope with the lack of the SIM in the architecture and how to realize roaming
Predictive Voice-Over-Internet Protocol Fallback over Vehicular Channels: Employing Artificial Intelligence at the Edge of 5G Networks
No full text5G cellular networks are characterized by a servicebased architecture (SBA) where physical and virtual network functions (NFs) interact with each other. In conjunction with multi-access edge computing (MEC), 5G systems are expected to enable a wide range of advanced applications for vertical industries as well as over-the-top (OTT) service providers. Although MEC typically processes user-plane data, in this article, we exploit it to process control-plane data via the 5G network exposure function (NEF), enabling new context-aware applications. Based on cell-specific radio access network (RAN) signaling, we envision a machine learning (ML) solution that learns the user-context evolution, where the ML engine runs on a MEC host and its prediction is used to change the network setup for a given application. As an example, to address the challenging, fast-changing vehicular channel, we describe a predictive fallback mechanism for Voice Over Internet Protocol (VoIP) calls, wherein critical channel conditions are predicted to anticipate the fallback to, e.g., a traditional voice call, thus ensuring service continuity to the end user
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
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