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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.
1

A model for privacy-aware presence management in mobile communications

Ophoff, Jacobus Albertus January 2011 (has links)
As humans we find communicating natural and compelling. Over the centuries we have created many innovations which enable and improve communication between people; during the past decade mobile phone networks have brought about a technological revolution in this area. Never before have people been so connected to one another. Today we have the ability to communicate with almost anyone, anytime, anywhere. Our increased connectivity and reachability also leads to new issues and challenges that we need to deal with. When we phone someone we expect an instant connection, and when this does not occur it can be frustrating. On the other hand it is equally disruptive to receive a call when one is busy with an important task or in a situation where communication is inappropriate. Social protocol dictates that we try to minimize such situations for the benefit of others nearby and for ourselves. This management of communications is a constant and difficult task. Using presence – which signals a person’s availability and willingness to communicate – is a solution to this problem. Such information can benefit communication partners by increasing the likelihood of a successful connection and decreasing disruptions. This research addresses the problem of staying connected while keeping control over mobile communications. It adopts a design-science research paradigm, with the primary research artifact being a model for privacy-aware presence management in mobile communications. As part of the model development knowledge contributions are made in several ways. Existing knowledge about the problem area is extended through a quantitative analysis of mobile communications management. This analysis uses a novel survey, collecting useful empirical data for future research. This includes how people currently manage their communications and what features they expect from a potential “call management” system. The examination and use of presence standards, as a foundation for the model, provides a comparison of the main presence technologies available today. A focus on privacy features identifies several shortcomings in standards which, if addressed, can help to improve and make these standards more complete. The model stresses the privacy of potentially sensitive presence information. A unique perspective based on social relationship theories is adopted. The use of relationship groups not only makes logical sense but also assists in the management of presence information and extends existing standards. Finally, the evaluation of the model demonstrates the feasibility of a practical implementation as well the ability to extend the model in next generation mobile networks. Thus the model presents a solid foundation for the development of future services. In these ways the proposed model contributes positively towards balancing efficient mobile communications with the need for privacy-awareness.
2

Affective gesture fast-track feedback instant messaging (AGFIM).

Adesemowo, A. Kayode January 2005 (has links)
Text communication is often perceived as lacking some components of communication that are essential in sustaining interaction or conversation. This interaction incoherency tends to make text communication plastic. It is traditionally devoid of intonation, pitch, gesture, facial expression and visual or auditory cues. Nevertheless, Instant Messaging (IM), a form of text communication is on the upward uptake both on PCs and on mobile handhelds. There is a need to rubberise this plastic text messaging to improve co-presence for text communications thereby improving synchronous textual discussion, especially on handheld devices. <br /> <br /> One element of interaction is gesture, seen as a natural way of conversing. Attaining some level of interaction naturalism requires improving synchronous communication spontaneity, partly achieved by enhancing input mechanisms. To enhance input mechanisms for interactive text-based chat on mobile devices, there is a need to facilitate gesture input. Enhancement is achievable in a number of ways, such as input mechanism redesigning and input offering adaptation. This thesis explores affective gesture mode on interface redesign as an input offering adaptation. This is done without a major physical reconstruction of handheld devices.<br /> <br /> This thesis presents a text only IM system built on Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE). It was developed with a novel user-defined hotkey implemented as a one-click context menu to &ldquo / fast-track&rdquo / text-gestures and emoticons.<br /> <br /> A hybrid quantitative and qualitative approach was taken to enable data triangulation. Results from experimental trials show that an Affective Gesture (AG) approach improved IM chat spontaneity/response. Feedback from the user trials affirms that AG hotkey improves chat responsiveness, thus enhancing chat spontaneity.
3

Silicon MOS field effect transistor RF/Microwave nonlinear model study and power amplifier development for wireless communications

Heo, Deukhyoun 12 1900 (has links)
No description available.
4

Affective gesture fast-track feedback instant messaging (AGFIM).

Adesemowo, A. Kayode January 2005 (has links)
Text communication is often perceived as lacking some components of communication that are essential in sustaining interaction or conversation. This interaction incoherency tends to make text communication plastic. It is traditionally devoid of intonation, pitch, gesture, facial expression and visual or auditory cues. Nevertheless, Instant Messaging (IM), a form of text communication is on the upward uptake both on PCs and on mobile handhelds. There is a need to rubberise this plastic text messaging to improve co-presence for text communications thereby improving synchronous textual discussion, especially on handheld devices. <br /> <br /> One element of interaction is gesture, seen as a natural way of conversing. Attaining some level of interaction naturalism requires improving synchronous communication spontaneity, partly achieved by enhancing input mechanisms. To enhance input mechanisms for interactive text-based chat on mobile devices, there is a need to facilitate gesture input. Enhancement is achievable in a number of ways, such as input mechanism redesigning and input offering adaptation. This thesis explores affective gesture mode on interface redesign as an input offering adaptation. This is done without a major physical reconstruction of handheld devices.<br /> <br /> This thesis presents a text only IM system built on Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE). It was developed with a novel user-defined hotkey implemented as a one-click context menu to &ldquo / fast-track&rdquo / text-gestures and emoticons.<br /> <br /> A hybrid quantitative and qualitative approach was taken to enable data triangulation. Results from experimental trials show that an Affective Gesture (AG) approach improved IM chat spontaneity/response. Feedback from the user trials affirms that AG hotkey improves chat responsiveness, thus enhancing chat spontaneity.
5

Implementation of location detection, home agent discovery and registration of mobile IPv6 /

Xu, Yang, January 1900 (has links)
Thesis (M.C.S.)--Carleton University, 2001. / Includes bibliographical references (p. 77-79). Also available in electronic format on the Internet.
6

Wireless communication for sparse and rural areas

Zhang, Mingliu. January 2007 (has links) (PDF)
Thesis (Ph.D.)--Montana State University--Bozeman, 2007. / Typescript. Chairperson, Graduate Committee: Richard Wolff. Includes bibliographical references.
7

Support for Cell Broadcast as Global Emergency Alert System

Axelsson, Karin, Novak, Cynthia January 2007 (has links)
<p>Cell Broadcast (CB) is a possible technical realisation of a global emergency alert system. It is a technique used for sending short text messages to all mobile stations (MSs) in a defined geographical area. An potential effect of using CB is the increase in battery consumption of the MS due to the fact that an extra channel has to be used to make the service available even when the network is otherwise congested. Another part of the service which leads to a potential problem is making CB messages available in different languages. Investigating these problems is the objective of this thesis and the studies it includes. During the first part of the thesis, we measured the battery consumption of MSs in different modes of operation in order to analyse how CB affects the amount of current drained. The tests showed that battery consumption increased only slightly when CB messages were being received at the MS. Although some of the results can be, and are, discussed, we believe that CB would have a small effect on the power consumption of an MS, particularly in a context where it would be used for emergency warning messages only. This mentioned, it would however be wishful to confirm the conclusions further through the realisation of long-term testing. The second part of the thesis deals with the investigation of the MSs’ support for CB messages with different coding schemes. Based on the investigation’s result, we have come to the conclusion that in the long term the usage of different coding schemes on the same channel is preferred. However, the usage of one, global, emergency channel is hard to realise since that requires a standardisation between all countries. In our opinion this may be achieved first in the long run and until then, the usage of separate channels seems to be necessary.</p>
8

Support for Cell Broadcast as Global Emergency Alert System

Axelsson, Karin, Novak, Cynthia January 2007 (has links)
Cell Broadcast (CB) is a possible technical realisation of a global emergency alert system. It is a technique used for sending short text messages to all mobile stations (MSs) in a defined geographical area. An potential effect of using CB is the increase in battery consumption of the MS due to the fact that an extra channel has to be used to make the service available even when the network is otherwise congested. Another part of the service which leads to a potential problem is making CB messages available in different languages. Investigating these problems is the objective of this thesis and the studies it includes. During the first part of the thesis, we measured the battery consumption of MSs in different modes of operation in order to analyse how CB affects the amount of current drained. The tests showed that battery consumption increased only slightly when CB messages were being received at the MS. Although some of the results can be, and are, discussed, we believe that CB would have a small effect on the power consumption of an MS, particularly in a context where it would be used for emergency warning messages only. This mentioned, it would however be wishful to confirm the conclusions further through the realisation of long-term testing. The second part of the thesis deals with the investigation of the MSs’ support for CB messages with different coding schemes. Based on the investigation’s result, we have come to the conclusion that in the long term the usage of different coding schemes on the same channel is preferred. However, the usage of one, global, emergency channel is hard to realise since that requires a standardisation between all countries. In our opinion this may be achieved first in the long run and until then, the usage of separate channels seems to be necessary.
9

Novas tecnicas de processamento espaço-temporal em transmissão conciliando diversidade e beamforming / New methods for transmit space-time processing combining diversity and beamforming

Zanatta Filho, Danilo 11 January 2006 (has links)
Orientador: João Marcos Travassos Romano / Tese (doutorado) - Universidade Estadual de Campinas. Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-07T23:30:42Z (GMT). No. of bitstreams: 1 ZanattaFilho_Danilo_D.pdf: 1987916 bytes, checksum: be6038a70235bda4b62a193a0296ffb7 (MD5) Previous issue date: 2006 / Resumo: O presente trabalho trata da utilização, em transmissão, de um arranjo de antenas na estação rádio-base de um sistema de comunicação celular. Na recepção, as soluções para explorar o arranjo são atualmente bem estabelecidas na literatura. Por outro lado, na transmissão, o problema se mantém aberto. Duas abordagens são possíveis: explorar o arranjo de antenas em beamforming ou em diversidade. Essas duas abordagens se opõem pelas hipóteses sobre a correlação dos canais, o que implica um maior ou menor espaçamento entre as antenas, de acordo com o ambiente de propagação. Na prática, essas hipóteses são muito difíceis de se respeitar. Nesta dissertação, pretendemos tratar esta questão na sua globalidade, conciliando diversidade e beamforming para melhor explorar o arranjo de antenas. Consideramos o contexto monousuário, assim como o caso multiusuário. No caso monousuário, propomos uma estrutura de transmissão composta por uma técnica de diversidade de transmissão clássica aplicada a antenas virtuais diretivas e idealmente independentes. Essas antenas virtuais são fabricadas por meio de filtros puramente espaciais aplicados às antenas reais. O conjunto desses filtros é chamado precoder e se intercala entre a diversidade de transmissão e o arranjo de antenas utilizado em transmissão. Esse precoder desempenha um duplo papel, o de realizar o beamforming e o de criar a diversidade por meio de antenas virtuais idealmente independentes, conciliando assim diversidade de transmissão e beamforming em transmissão. Duas abordagens são propostas para se obter o precoder , uma baseada na minimização da variância da potência recebida pelo móvel e a segunda baseada diretamente na minimização da taxa de erro. Comparadas às técnicas clássicas, as novas técnicas apresentam melhores desempenhos. Em seguida, propomos uma extensão dessa estrutura ao contexto multiusuário, para o qual técnicas de diversidade de transmissão ainda não foram propostas na literatura. Propomos a adaptação conjunta dos precoders, buscando minimizar a potência total de transmissão, respeitando as BERs alvo dos usuários. De maneira análoga ao caso monousuário, os precoders permitem conciliar beamforming e diversidade de transmissão. Comparada às técnicas clássicas de beamforming multiusuário, a nova abordagem introduz diversidade de transmissão ao enlace, apresentando melhores desempenhos / Abstract: This work deals with the use of an antenna array at the base station of a mobile communication system for transmission. In reception, solutions that exploit the antenna array are now well established. In transmission, however, the problem remains open. Two approaches are possible: exploit the array by using beamforming techniques or by using diversity techniques. These two approaches are based on opposing assumptions about the channels correlation, which implies a greater or smaller distance between antennas, depending on the environment. In practice, these assumptions are not verified. Here, we aim to deal with the problem as a whole for better exploiting the antenna array. This work treats the single-user case, as well as the multiuser scenario. In the single-user case, we propose a transmission scheme composed of a classical transmit diversity technique applied to virtual antennas, which are directive and ideally independent. These virtual antennas are produced by means of purely spatial filters applied to the real antennas. This set of filters is called precoder, and acts as the interface between the transmit diversity technique and the transmit antenna array. The precoder function is twofold; to beamform the transmit signal, and to create diversity by means of ideally independent virtual antennas, thus combining transmit diversity and transmit beamforming. We propose two approaches to obtain this precoder, one based on the minimization of the variance of the received power at the mobile, and the other directly based on the minimization of the error rate. Compared to more classical approaches, the performance of the new methods reveals their advantage. Then, we extend this scheme to a multiuser context, for which transmit diversity techniques have not yet been developed. We propose to jointly adapt the precoders by minimizing the total transmit power while satisfying the users¿ target BER. Similarly to the single-user case, the precoders allow to combine beamforming and transmit diversity. Compared to classical multiuser beamforming techniques, the new approach adds diversity to the link and obtains in return better performances / Doutorado / Telecomunicações e Telemática / Doutor em Engenharia Elétrica
10

Affective gesture fast-track feedback instant messaging (AGFIM)

Adesemowo, A. Kayode January 2005 (has links)
Magister Scientiae - MSc / Text communication is often perceived as lacking some components of communication that are essential in sustaining interaction or conversation. This interaction incoherency tends to make text communication plastic. It is traditionally devoid of intonation, pitch, gesture, facial expression and visual or auditory cues. Nevertheless, Instant Messaging (IM), a form of text communication is on the upward uptake both on PCs and on mobile handhelds. There is a need to rubberise this plastic text messaging to improve co-presence for text communications thereby improving synchronous textual discussion, especially on handheld devices. One element of interaction is gesture, seen as a natural way of conversing. Attaining some level of interaction naturalism requires improving synchronous communication spontaneity, partly achieved by enhancing input mechanisms. To enhance input mechanisms for interactive text-based chat on mobile devices, there is a need to facilitate gesture input. Enhancement is achievable in a number of ways, such as input mechanism redesigning and input offering adaptation. This thesis explores affective gesture mode on interface redesign as an input offering adaptation. This is done without a major physical reconstruction of handheld devices. This thesis presents a text only IM system built on Session Initiation Protocol (SIP) and SIP for Instant Messaging and Presence Leveraging Extensions (SIMPLE). It was developed with a novel user-defined hotkey implemented as a one-click context menu to "fast-track" text-gestures and emoticons. A hybrid quantitative and qualitative approach was taken to enable data triangulation. Results from experimental trials show that an Affective Gesture (AG) approach improved IM chat spontaneity/response. Feedback from the user trials affirms that AG hotkey improves chat responsiveness, thus enhancing chat spontaneity.

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