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Study on Energy-Efficiency Enhancement Techniques for 5G Cellular Networks
Get PDF三重大学博士(工学)application/pdf内容の要旨・審査結果の要旨/システム工学専攻thesi
Study on Energy-Efficiency Enhancement Techniques for 5G Cellular Networks
Get PDF三重大学博士(工学)application/pdf5G New Radio (NR) cellular network is expected to provide three major services including enhanced Mobile Broadband (eMBB), Ultra-Reliable Low Latency Communications (URLLC), and massive Machine Type Communication (mMTC). eMBB applications aim to achieve extremely high data rates. URLLC supports low-latency transmissions of small payloads with very high reliability. Meanwhile, mMTC targets to support the connectivity of billions of Internet of Things (IoT) devices. Importantly, this thesis focuses on achieving eMBB and URLLC services from the viewpoint of system-level solution. As the world adopts greener technologies and reduces energy waste, energy efficiency in wireless networks has become more important than ever. The 5G NR network is designed to improve energy efficiency, making research and network design a crucial component. 5G NR network is expected to meet the requirements for eMBB and URLLC. Several technologies are being integrated into 5G networks to meet the diverse needs of users. Such a complex network design will increase energy consumption. Consequently, energy efficiency becomes of the highest importance.
Considering that 5G NR cellular networks need to achieve eMBB services while ensuring seamless integration with all existing and emerging technologies, one of the most promising strategies for addressing these challenges involves the densification of base station (BS) deployments through the use of heterogeneous cellular networks (HetNets). HetNets consist of various tiers of base stations, which include both macro base stations (MBSs) and small base stations (SBSs). Typically, the SBS tier overlays on the MBS tier within HetNets. Consequently, the deployment of a HetNet, which combines MBSs and SBSs, can significantly improve the performance of 5G eMBB by increasing capacity, coverage, spectral efficiency, and overall user experience. Nevertheless, the dense implementation of SBSs within the MBS coverage results in a negative impact, such as an increase in energy consumption due to the inclusion of several SBSs, which can result in a decrease in energy efficiency on the network side. Therefore, various techniques for reducing energy consumption and enhancing energy efficiency in 5G NR cellular networks have been suggested. Despite the fact that these techniques can reduce energy consumption and improve energy efficiency, they may lead to a degradation in system throughput when compared to the no-sleep control system.
5G NR also provides URLLC services that satisfy the stringent latency and reliability requirements for one-way latency of 1 ms with 99.999% reliability. To satisfy URLLC requirements, grant-free (GF) transmissions with the K-repetition transmission (K-Rep) have been introduced. Due to its repeated operation, the K-Rep scheme significantly increases the number of packet transmissions. Consequently, an excessive increase in packet transmissions causes severe interference at the receiving BS, resulting in degraded reliability. Moreover, the increase in packet transmissions on the K-Rep scheme results in a significant increase in energy consumption, leading to the early depletion of the battery and a decrease in energy efficiency on the user equipment (UE) side.
To address the first problem, this thesis proposes an enhanced algorithm for SBS sleep control based on energy efficiency as a decision criterion for SBS operating state, with a primary focus on supporting eMBB services. Using energy efficiency as a decision criterion, the proposed sleep control algorithm aims to achieve a balance between reducing power consumption and maintaining system performance. The proposed algorithm employs a 2-phase control procedure, where the first phase selects tentative sleep SBSs based on their energy efficiency and the second phase activates additional SBSs from the sleep state to improve energy efficiency while maintaining system throughput. The results of computer simulation evaluation indicate that the proposed sleep control scheme can provide improved performance for both energy efficiency and system throughput simultaneously. In other words, it effectively enhances energy efficiency while maintaining practically the same system throughput as the no-sleep control system.
To overcome the second problem of severe interference and reduced energy efficiency on the UE side resulting from an increase in packet transmissions in GF URLLC, this thesis proposes two innovative adaptive K-Rep control schemes. These schemes employ site diversity reception with the primary objective of reducing the number of packet transmissions. The first of these adaptive K-Rep control schemes, presented as adaptive K-Rep control scheme I, assigns a different number of associated cells to each UE. Meanwhile, the second scheme, known as adaptive K-Rep control scheme II, assigns a constant number of associated cells for all UEs. In adaptive K-Rep control scheme I, the number of packet transmissions for each UE is dynamically adjusted based on the specific number of associated cells for all UEs, whereas in adaptive K-Rep control scheme II, the dynamic adjustment of packet transmissions based on the variation in the reference signal received power (RSRP) levels. The performance evaluation demonstrates that the proposed adaptive K-Rep control schemes significantly improve communication reliability and reduce transmission energy consumption compared with the conventional K-Rep scheme, thereby satisfying the URLLC requirements while reducing energy consumption and enhancing energy efficiency at the UE side.
From the numerous computer simulation results at the system level evaluation, it is confirmed that the proposed schemes present in this thesis can be employed as solutions to enhance energy efficiency for eMBB services at the network side and for URLLC services at the UE side within the context of a 5G NR cellular network.本文/Division of Systems Engineering Graduate School of Engineering Mie University98pdoctoral thesi
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
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