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Full-Duplex Communications in Large-Scale Cellular NetworksAlammouri, Ahmad 04 1900 (has links)
In-band full-duplex (FD) communications have been optimistically promoted to improve the spectrum utilization and efficiency. However, the penetration of FD communications to the cellular networks domain is challenging due to the imposed uplink/downlink interference. This thesis presents a tractable framework, based on stochastic geometry, to study FD communications in multi-tier cellular networks. Particularly, we assess the FD communications effect on the network performance and quantify the associated gains. The study proves the vulnerability of the uplink to the downlink interference and shows that the improved FD rate gains harvested in the downlink
(up to 97%) comes at the expense of a significant degradation in the uplink rate (up to 94%). Therefore, we propose a novel fine-grained duplexing scheme, denoted as α-duplex scheme, which allows a partial overlap between the uplink and the downlink frequency bands. We derive the required conditions to harvest rate gains from the α-duplex scheme and show its superiority to both the FD and half-duplex (HD) schemes. In particular, we show that the α-duplex scheme provides a simultaneous improvement of 28% for the downlink rate and 56% for the uplink rate. We also show that the amount of the overlap can be optimized based on the network design objective.
Moreover, backward compatibility is an essential ingredient for the success of new technologies. In the context of in-band FD communication, FD base stations (BSs) should support HD users' equipment (UEs) without sacrificing the foreseen FD gains. The results show that FD-UEs are not necessarily required to harvest rate gains from FD-BSs. In particular, the results show that adding FD-UEs to FD-BSs offers a maximum of 5% rate gain over FD-BSs and HD-UEs case, which is a marginal gain compared to the burden required to implement FD transceivers at the UEs' side. To this end, we shed light on practical scenarios where HD-UEs operation with FD-BSs outperforms the operation when both the BSs and UEs are FD and we find a closed
form expression for the critical value of the self-interference cancellation power required for the FD UEs to outperform HD UEs.
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Rychlé číslicové filtry pro signály EKG / Fast Digital filters for ECG SignalsRáček, Tomáš January 2011 (has links)
In the thesis there are described the implementations of various types of filters to remove disturbing signals, which often degrade the ECG signal. In particular, it is a zero isoline fluctuations and power network interference. It is used a principle of the Lynn’s linear filters. The individual filters are designed in a recursive and non-recursive implementation. Then there is described a time-varying linear Lynn's filter for removing drift of zero isoline signal. The thesis also includes filters with minimized calculating time of response, by sampling rate conversion method for both interference types. In conclusion there is an experimental study of the filter implementation for ECG signal with false and real interferences.
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A study and the evaluation of real time performance of Samancor’s Profibus networkMahlangu, Patrick Amos 02 1900 (has links)
The field buses, and particularly the ‘PROFIBUS’, are currently widely used in automation systems, with the intention to automate industrial applications. It is of the utmost importance that one should understand how these systems operate, because failure to understand may result in improper applications, which can ultimately lead to intense network problems and, consequently, lead to potential catastrophic failures in industrial equipment, as well as compromising the health and safety of the people.
This research was the performance evaluation of SAMANCOR PROFIBUS network that controls the chrome manufacturing plant. The problem with the network was that it was failing intermittently. These network failures resulted in loss of production, loss of throughput, compromised quality, downtime due to reworks, high costs in energy used to rework, and equipment damage or failure.
One of the OBJECTIVES of the research was to carry out a performance evaluation of the PROFIBUS network in terms of the possible electromagnetic interference (EMI) within the plant’s PLC network. This topic emanated from the network service providers that kept insisting that the network was unstable, due to possible electromagnetic interference caused by possible high voltage cables running next to the plant network cables. This assumption was without fact, and hence the research was conducted.
The QUANTITATIVE research method was used to conduct the research, where simulation of the plant network, using external parameters, were used to carry out the research. Furthermore, experiments were conducted and the physical measurements were performed on the network, where parameters derived from these measurements were used to compare the two networks. In essence, the network was tested under known configurations. The manner in which the network was simulated was that of stepping up the electrical current from the external device, and recording the response of the network. A stand-alone network rig was built and used to carry out the tests, and the results were compared with those obtained from the plant network. / Electrical and Mining Engineering / M. Tech. (Electrical Engineering)
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Internet censorship in the European UnionVerveris, Vasilis 30 August 2023 (has links)
Diese Arbeit befasst sich mit Internetzensur innnerhalb der EU, und hier
insbesondere mit der technischen Umsetzung, das heißt mit den angewandten
Sperrmethoden und Filterinfrastrukturen, in verschiedenen EU-Ländern. Neben
einer Darstellung einiger Methoden und Infrastrukturen wird deren Nutzung zur
Informationskontrolle und die Sperrung des Zugangs zu Websites und anderen im
Internet verfügbaren Netzdiensten untersucht. Die Arbeit ist in drei Teile
gegliedert. Zunächst werden Fälle von Internetzensur in verschiedenen EU-Ländern
untersucht, insbesondere in Griechenland, Zypern und Spanien. Anschließend wird
eine neue Testmethodik zur Ermittlung der Zensur mittels einiger Anwendungen,
welche in mobilen Stores erhältlich sind, vorgestellt. Darüber hinaus werden
alle 27 EU-Länder anhand historischer Netzwerkmessungen, die von freiwilligen
Nutzern von OONI aus der ganzen Welt gesammelt wurden, öffentlich zugänglichen
Blocklisten der EU-Mitgliedstaaten und Berichten von
Netzwerkregulierungsbehörden im jeweiligen Land analysiert. / This is a thesis on Internet censorship in the European Union (EU),
specifically regarding the technical implementation of blocking methodologies
and filtering infrastructure in various EU countries. The analysis examines the
use of this infrastructure for information controls and the blocking of access
to websites and other network services available on the Internet. The thesis
follows a three-part structure. Firstly, it examines the cases of Internet
censorship in various EU countries, specifically Greece, Cyprus, and Spain.
Subsequently, this paper presents a new testing methodology for determining
censorship of mobile store applications. Additionally, it analyzes all 27 EU
countries using historical network measurements collected by Open Observatory
of Network Interference (OONI) volunteers from around the world, publicly
available blocklists used by EU member states, and reports issued by network
regulators in each country.
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