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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Performance analysis and call control procedures in high-speed multimedia personal wireless communications / Sam (Shaokai) Yu.

Yu, Sam Shaokai January 1999 (has links)
Bibliography: leaves 203-219. / 226 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Develops efficient analytical methodologies for multimedia traffic integration and improved design tools to enhance data performance. The call admission control policies proposed are not only able to enhance traffic performance but also maintain communication quality at an acceptable level. In particular, the multiple priority scheme is a promising technique for the control of packet congestion in a high-speed wireless multimedia environment. / Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2000?
22

Bounds and algorithms for carrier frequency and phase estimation

Rice, Feng January 2002 (has links)
Quadrature amplitude modulation (QAM) is a highly bandwidth efficient transmission technique for digital communications. It makes use of multiple signal phase and amplitude levels to carry multiple bits per symbol. This requires accurate and robust carrier phase and frequency estimation in the receiver. / Thesis (PhDElectronicEngineering)--University of South Australia, 2002
23

Personnel tracking system using a bluetooth-based epidemic protocol

Sosa, Abimael, January 2007 (has links)
Thesis (M.S.)--University of Texas at El Paso, 2007. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
24

Performance analysis and call control procedures in high-speed multimedia personal wireless communications /

Yu, Sam Shaokai. January 1999 (has links) (PDF)
Thesis (Ph.D.)--University of Adelaide, Dept. of Electrical and Electronic Engineering, 2000? / Bibliography: leaves 203-219.
25

An enhanced method for the existing bluetooth pairing protocol to avoid impersonation attacks

Mendoza, Patricia A., January 2009 (has links)
Thesis (M.S.)--University of Texas at El Paso, 2009. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.
26

Performance evaluation of multi-hop WPANS based on a realistic OFDM UWB physical layer

Gao, Hongju1972-, January 2007 (has links)
Thesis (Ph. D.)--Rutgers University, 2007. / "Graduate Program in Electrical and Computer Engineering." Includes bibliographical references (p. 97-99).
27

Interference characterization in unlicensed national information infrastructure (U-NII) band /

Masood, Zafar, January 1900 (has links)
Thesis (M.Eng.) - Carleton University, 2001. / Includes bibliographical references (p. 81-84). Also available in electronic format on the Internet.
28

Designs on the mechanism economics and the FCC spectrum auctions /

Nik-Khah, Edward M. January 2005 (has links)
Thesis (Ph. D.)--University of Notre Dame, 2005. / Thesis directed by Philip E. Mirowski for the Department of Economics. "December 2005." Includes bibliographical references (leaves 152-165).
29

Improving the capacity and the quality of service of a DS-CDMA cellular system with integrated services

Zou, Jialin 15 June 2018 (has links)
In the design of the third generation of multi-media wireless networks, we are primarily concerned with the greatly varying information source rates, the quality requirements of various traffic types, the characteristics of the wireless environment, as well as the complexity and cost. Code Division Multiple Access (CDMA) cellular system is one of the most important candidates for supporting the future universal communications services. The objective of this research is to improve the capacity and the quality of service (QOS), as well as to reduce the complexity of cellular CDMA with integrated services, through improving or optimizing the design of system level operations. To facilitate the system performance and capacity evaluation, the multi-cell multi-user interference is analyzed through a new approach. The area averaged probability density function (PDF) of interference power from one active user is evaluated. The Gamma distribution is proposed for modelling the area averaged PDF of the interference power. An efficient method for evaluating system performance is developed. Differing from the Gaussian approximation, this method is very effective and accurate for both a large number and a small number of users. In this research, differing from the distance membership determination, the statistical effect of handoff is considered. The effects of soft handoff operation on multi-cell multi-user interference are analyzed. Membership statistics which are determined by soft handoff are investigated. A simple binomial model is proposed for modelling the distribution of the number of users belonging to a base station. Considering the call arrival statistics, user membership statistics and a finite number of channels available at a base station, we evaluate the call blocking/dropping rate. The minimum number of channels required at a base-station, which ensures a specified quality of service at a given capacity requirement, is determined. System capacity is further evaluated considering both outage probability limited by interference and call blocking/dropping rate limited by finite number of channels. A pilot assisted channel allocation method is proposed to minimize the number of channels required at a base station. Based on the analysis of a CDMA cellular system with a single traffic type, the design issues in developing a multi-media wireless networks are further discussed. The capacity of a CDMA cellular system with high quality requirements and mixed stream and packet types of traffic is assessed. The impact of the choice of a line rate (bit transmission rate through channel) on the system capacity is investigated. It is also shown that the power allocated to different types of traffic can be optimized to achieve maximum capacity. The optimum power allocation suggests that the power assignments to different traffic types are mainly determined by their quality requirements. / Graduate
30

[en] MOBILITY MANAGEMENT IN MOBILE CELLULAR COMMUNICATION NETWORS / [pt] GERÊNCIA DE MOBILIDADE EM REDES DE COMUNICAÇÃO MÓVEL CELULAR

PAULO ROBERTO DE LIRA GONDIM 08 June 2006 (has links)
[pt] Nos últimos anos, considerável debate tem ocorrido a respeito do tema gerência de mobilidade, face à necessidade de se fazer uso judicioso dos recursos de sinalização destinados para esse fim no âmbito de sistemas de comunicação móvel celular e de sistemas de comunicação pessoal (PCS). Dentre as estratégias de gerência de mobilidade, destaca-se a utilização do conceito de áreas de registro, amplamente empregadas a partir dos sistemas de 2a. geração, e permitindo reduzir o consumo de recursos devido a atualizações de localização. Outro conceito, o de áreas de paging, tem também se tornado bastante difundido, propiciando a economia de recursos gastos na procura de terminais móveis por ocasião de tentativas de completamento de chamadas para estes terminais. Este trabalho inicia-se com discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se no contexto do trabalho o modelo baseado em fluxo de fluídos e o modelo gravitacional. O problema de particionamento em áreas de localização (LAPP) é então tratado como um problema de particionamento de grafos, cuja elevada complexidade enseja a utilização de heurísticas capazes de propiciar a obtenção de soluções próximas da ótima. As heurísticas propostas destinam-se ao caso mais comum, em que áreas de localização são coincidentes com áreas de paging. Com base em metodologia utilizada para o LAPP, são propostas soluções para um outro problema, o ISHMP (Inter-Switch Handover Minimization Problem), cuja importância se prende não só ao elevado consumo de recursos mas também aos atrasos impostos pelo sistema aos usuários quando estes trocam de área de Mobile Switching Center. Assim, reduzir ao máximo a ocorrência de tais eventos é vantajoso tanto do ponto de vista do usuário quanto do sistema. As heurísticas propostas são essencialmente as mesmas para ambos os problemas, e mostram superioridade em termos de qualidade das soluções obtidas quando comparadas com propostas de outros autores, através de casos-padrão publicados na literatura e de testbed construído especialmente para a comparação. Apresenta-se ainda discussão a respeito de modelos de mobilidade empregados no estudo de problemas e técnicas da área de comunicações móveis. Dentre tais modelos, destacam- se o modelo baseado em fluxo de fluidos e o modelo gravitacional. O trabalho apresenta também estudo relativo às cargas de sinalização que ocorrem tnato na rede fixa (incluindo o tráfego de consultas e atualizações sobre as bases de dados) quanto na interface aérea. No apêndice, considerando o grafo que modela a rede celular, apresenta-se comprovação formal da conversão de pesos de nós e de arestas em novos pesos de arestas, permitindo o tratamento dos dois problemas de particionamento aqui abordados como problemas de edgepartitioning puros. / [en] In the past few years there hás been considerable debate over the question of mobility management in móbile cellular communication networks, due to the need of using the signaling system resources in a careful way. Among the strategies of location management, the utilization of registration areas has been difunded since the emergence of the second generation mobile communication systems, allowing to reduce the resource consumption due to location updates. Another concept, named paging areas, has also been extensively employed, allowing to save resources utilized localization of mobile terminals during the call setup for mobile stations. Initially, the Location Area Partitioning Problem (LAPP) is treated as a graph partitioning problem, largely recognized as NP-complete ([GARE 79], [LENG 90]) and leading to the utilization of heuristics, able to produce good sub-optimal solutions. The heuristics are proposed to solve the more usual case, where location areas are coincident with paging areas, and the frequency spectrum (radio resources). With the same methodology, another problem, named Inter- Switch Handover Minimization Problem (ISHMP), is adequately solved, being its relevance due to the elevated system resource consumption and to the severe delays imposed to users when their Mobile Switching Centers are changed. Thus, the diminution of the occurrence of such events id advantageous from both the user`s and the system`s points of view. The heuristics are eddentially the same for the two problems, and it is shown the superiority of the quality of the quality of the obtained solutions, when comparing them with other published results. The work also presents discussion about mobility models employed in the study of problems and techniques in the mobile communications area. Among such models, the fluid flow and the gravitational models are highlighted. A study concerning to the signaling load imposed to the fixed network (including queries and location update traffic over databases) and to the air interface is presented. Finally, starting from the average rate of mobile terminated calls and from a previously defined user impatience threshold, a new proposal for the definition of the optimal number of cells per paging area is presented.

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