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Dissertations / Theses on the topic 'Mobile telecommunication systems'
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Stevens, David Story. "TDMA slot allocation strategies for mobile packet radio networks." Diss., Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/9190.
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Wang, Yuanyuan. "Browser-based and mobile video communication alternatives for Deaf people." Thesis, University of the Western Cape, 2011. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_5753_1319028741.
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<p>This thesis o ers some prototypes to provide browser-based and mobile video communication services for Deaf people and evaluates these prototypes. The aim of this research is to identify an acceptable video communication technology for Deaf people by designing and evaluating several prototypes. The goal is to nd one that Deaf people would like to use in their day-to-day life. The thesis focuses on two technologies | browser-based systems and mobile applications. Several challenges emerged, for example, speci c Deaf user requirements are di cult to obtain, the technical details must be hidden from end users, and evaluation of prototypes includes both technical and social aspects. This thesis describes work to provide South African Sign Language communication for Deaf users in a disadvantaged Deaf community in Cape Town. We posit an experimental design to evaluate browser-based and mobile technologies in order to learn what constitutes acceptable video communication for Deaf users. Two browser-based prototypes and two mobile prototypes were built to this e ect. Both qualitative data and quantitative data are collected with user tests to evaluate the prototypes. The video quality of Android satis es Deaf people, and the portable asynchronous communication is convenient for Deaf users. The server performance is low on bandwidth, and will therefore cost less than other alternatives, although Deaf people feel the handset is costly.</p>
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To, Sin Yam. "Quality of service framework for mobile ad hoc networks /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?COMP%202003%20TO.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.<br>Includes bibliographical references (leaves 122-124). Also available in electronic version. Access restricted to campus users.
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Diehl, Andreas. "Software architecture for data storage concepts within future mobile telecommunication systems." Thesis, University of Plymouth, 2007. http://hdl.handle.net/10026.1/332.
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In current mobile telecommunication networks, databases and the subscriber data is distributed among multiple network domains and database systems. The heterogeneous data storage concept is based on the permanent evolution of the mobile networks and the support of different kinds of network technologies. Dependent on the particular network domain and the dedicated technology, distributed subscriber data has to be accessed via specialised protocols.This thesis proposes a novel software architecture for the next generation profile register (NGPR) - an approach to provide subscriber information using a logically centralised register for subscriber data from several mobile network domains. The NGPR subscriber data model supports a network-independent layer that references to different kinds of network-specific data (such as subscribed services, user related data and run-time data). Appropriate adapters ensure the reusage of network-independent data for several specific mobile core domains or administrative systems. This thesis includes an UMTS interoperability concept for the SS7 (signaling system no. 7) and IP-based domains by utilising the service-oriented architecture (SOA). SOA concepts provide the flexibility to integrate different network-specific domains by data services. The data services (based on web services technology) are supported in a conventional way and by a binary mode in order to improve performance for the telecommunication networks. The service framework of the NGPR manages data services in general and links requests from the mobile domains to relevant subsets of subscriber data. NGPR data services support network-specific and generic interfaces that are proposed within concepts of the next generation networks or UMTS release 6. Based on SOA, the NGPR architecture provides subscriber data convergence and simplified data access. Therefore, several specialised and generic network domains can be directly supported by the network-independent layer of the NGPR. Especially administrative systems and network nodes of closed domains are supposed to take advantage of the interoperability concept and the converged data of the NGPR.
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Murufu, Mufudzi Anesu Chapman. "Development of an M-commerce security framework." Thesis, University of Fort Hare, 2014. http://hdl.handle.net/10353/833.
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Research shows how M-Commerce has managed to find its way to previously inaccessible parts of the world as a major Information and Communication Technologies (ICT) tool for development due to widespread introduction of mobile phones in remote areas. M-Commerce has offered valuable advantages: anytime, anywhere, more personal, more location-aware, more context-aware, more age aware, always online and instant connectivity. But this is not without its problems, of which security is high on the list. The security issues span the whole M-Commerce spectrum, from the top to the bottom layer of the OSI network protocol stack, from machines to humans. This research proposes a threat-mitigation modular framework to help address the security issues lurking in M-Commerce systems being used by marginalised rural community members. The research commences with a literature survey carried out to establish security aspects related to M-Commerce and to determine requirements for a security framework. The framework classifies M-Commerce security threat-vulnerability-risks into four levels: human behaviour and mobile device interaction security, mobile device security, M-Commerce access channel security, wireless network access security. This is followed by a review of the supporting structures or related frameworks that the proposed framework could leverage to address security issues on M-Commerce systems as ICT4D initiatives. The proposed security framework based on the requirements discovered is then presented. As a proof-of-concept, a case study was undertaken at the Siyakhula Living Lab at Dwesa in the Eastern Cape province of South Africa in order to validate the components of the proposed framework. Following the application of the framework in a case study, it can be argued that the proposed security framework allows for secure transacting by marginalised users using M-Commerce initiatives. The security framework is therefore useful in addressing the identified security requirements of M-Commerce in ICT4D contexts.
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Sarrocco, Claudia. "Legal aspects of the mobile satellite telecommunications services." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31173.
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Thanks to the use of satellite technology, mobile personal telecommunications systems are able to provide communications simultaneously anywhere on the Earth's surface. The implementation of such systems raises several regulatory issues: after a brief explanation of the technical characteristics of different satellite systems in the first chapter, the second chapter will introduce the principles of space law relevant to satellite communications, with particular attention to the provisions which the development of global satellite telecommunication system could infringe. In the third chapter, there will be place for further analysis of international regulations established in the framework of the International Telecommunication Union and the World Trade Organisation, dealing more specifically with satellite telecommunications. The discipline established by the former organisation aims to the optimal management of the orbit and spectrum resources, particularly controversial because of the divergence of interests and exigencies of the member countries, whereas the latter intervened in the liberalisation of the telecommunication services, with the purpose to create an open environment for their diffusion. Furthermore, telecommunication activities are subjected to national regulation. The domestic discipline pertaining to global mobile satellite telecommunication services will be analysed in the fourth chapter, with particular attention to the U.S. Federal Communication Commission regulations and to the developments of Italian legislation in the light of the recent European initiatives in the field. National authorisation requirement conditions, in spite of the international effort toward regulatory harmonisation and liberalisation, are the key elements in the deployment of global mobile telecommunications services. National authorities should not continue to function solely on the basis of their national considerations, but be more flexible and open to cooperation, a
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Umuhoza, Denise. "Metric of trust for mobile ad hoc networks using source routing algorithms." Thesis, University of the Western Cape, 2006. http://etd.uwc.ac.za/index.php?module=etd&action=viewtitle&id=gen8Srv25Nme4_8946_1183465240.
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<p>This thesis proposed and presented technical details of new probabilistic metrics of trust in the links wireless ad hoc networks for unobservable communications. In covert communication networks, only the end nodes are aware of the communication characteristics of the overall path. The most widely used protocols of ad hoc networks was overviewed. The routing protocols of ad hoc networks with trust considerations and select Destination Sequence Routing, a protocol that can be used in distributed ad hoc network settings for path discovery, was also reviewed. It establishes a path through which all packets sent by a source must pass to the destination. The end nodes are responsible for examining the statistics of the received packets and deriving inferences on path feature variations which are used for computing new trust metrics. When a path is judged not trustworthy based on the metrics, the Destination Sequence Routing is informed to undertake a new trusted path discovery between the end points. The thesis added a new feature based on the quality of service parameters of the path to create trust in the links in recognition of attacks.</p>
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Pettersen, Magne. "Three-Dimensional Radio Channel Modeling for Mobile Communications Systems." Doctoral thesis, Norwegian University of Science and Technology, Faculty of Information Technology, Mathematics and Electrical Engineering, 2001. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-89.
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<p>The work described in this report is within the area of three-dimensional (3D) radio channel modeling for mobile communications. The focus was towards rural areas, because radio coverage of rural areas is more costly when using higher frequencies, comparing UMTS to GSM. In addition seasonal and environmental variations are strongest here. The model used was a 3D <i>radar mode</i>l, comprised of a 2D vertical Tx-Rx-plane component and a 3D components to include off-axis scattering. The latter components are estimated using bistatic radar techniques. The model is able to provide an accurate estimation of the path loss (signal level), and is also able to estimate time dispersion and angular dispersion, taking into account off-axis contributions. Radio frequencies around 2 GHz were selected, as these are the most important frequency bands for 3. generation mobile systems, even though the envisaged approach supports radio planning for GSM 900 and WLAN systems.</p><p>A novel approach to the modeling of scattering from random rough surfaces for 3D channel modeling was developed. This amplitude/phase model is simple and accurate compared to conventional models. It makes no inherent assumption about the degree of roughness, making it suited to model all surfaces. The model outperforms the conventional models Plane surface, SPM, Kirchoff and Oren with respect to accuracy by 1.5 to 10 dB depending on the degree of roughness.</p><p>An experimental methodology to characterise random rough surfaces was developed. The work characterised natural surfaces such as asphalt, grass, agriculture, and forest, each of them having a different degree of roughness. Variations due to weather and seasonal changes were taken into account. Typical surface height variations estimated were 10 mm for asphalt, 25 mm for grass, 100 mm for ploughed field and 500 mm for forest. Snow reduced the apparent roughness of ploughed field by 50 %, water on grass increased the reflection coefficient by 50 %.</p><p>An analysis of the implications of the results on 3D channel modeling was performed using a demonstration model. The analysis included a comparison between 2D and 3D model prediction for different area types and land use classes. Also the prediction sensitivity to seasonal and weather variations and model parameter variations were inspected. A 3D model is necessary when the 2D component is attenuated more than typically 15 dB relative to free space, depending on area and land usage. In the network planning example Lillehammer (N) this attenuation of at least 15 dB existed in 40 % of all locations. Weather and seasonal variations may change the mean predicted value by up to 4-5 dB.</p>
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Mochizuki, Yujiro 1973. "Management of telecommunication systems design and development : learning from disruptive innovations in 3G mobile systems." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/17809.
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Thesis (S.M.M.O.T.)--Massachusetts Institute of Technology, Sloan School of Management, Management of Technology Program, 2004.<br>Includes bibliographical references (leaves 109-112).<br>Disruptive innovations in network systems are forcing mobile carriers to manage difficult network software development. Within the limited development time, mobile carriers are required to develop large scale, high quality and robust network software, and accomplish smooth transition/upgrading. In the drastic transition of the network architecture, network carriers often fail to develop platform network software. Compared with KDDI, NTT DoCoMo (DoCoMo) has been coping with network migration problems. The critical difference in both mobile carriers is whether the platform-based approach was applied sufficiently in the network software development. DoCoMo's insufficient platform-based approach led to migration difficulties. On the other hand, the consistent platform-based approach allowed KDDI to enjoy successful migration. In order to identify the critical factors in network software development related to this problem, this thesis (1) explores the characteristics of network innovations and (2) analyzes the platform innovations in mobile network software. The ultimate goal of this thesis is to (3) suggest how incumbent mobile carriers can avoid the potential threats and develop the platform network software in future disruptive network innovations. In the future, management of telecommunication systems design and development will face more challenging and more complicated migration because the network concepts and architecture will be completely different from those in the existing 3G networks. The lessons learned from the case studies DoCoMo and KDDI suggest ideas that mobile carriers can utilize to address tough situations.<br>(cont.) The platform-based approach definitely will help the migration strategies of mobile carriers and reduce the potential threats in current and future network systems.<br>by Yujiro Mochizuki.<br>S.M.M.O.T.
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Shih, Alexander (Alexander En-Tzu). "The contribution of mobile telecommunication technology to sustainable development in selected countries in Africa." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/70869.
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Thesis (S.M. in Engineering and Management, and, in Technology and Policy)--Massachusetts Institute of Technology, Engineering Systems Division, 2011.<br>Cataloged from PDF version of thesis.<br>Includes bibliographical references (p. 143-150).<br>While most of the world's population resides in countries that are wealthy or developing, the rest reside in low-income and least developed countries (LDCs), left behind and growing more disconnected. At the same time, mobile phones are widely adopted in these underdeveloped areas and demonstrate potential for economic development. However, technological innovation and policies have often addressed narrow dimensions of poverty and development. Sustainable development, on the other hand, assesses the welfare of a country in its entirety. This then begs the question of how mobile telephony technology, given its pervasiveness, can be beneficial on a systemic and sustainable level. This document presents evidence that mobile phones can contribute to sustainable development in several ways. The focus is on selected countries in the sub-Saharan Africa region: Kenya, Tanzania, Uganda, and Nigeria, each of which is categorized as a LDC. The Sustainable Development framework is used to analyze data from case studies and existing technology, institutional and policy trends in the mobile telecommunication industry. The evidence from literature demonstrates that mobile initiatives focused on niche areas, such as banking and health, have benefited on the community level and improved operations within firms. Mobile industry policies have created a healthy system of innovation in these countries. However, environmental development has been secondary or even ignored. Thus, the recommendations focus on prioritizing sustainability, specific policies continuing diffusion and adoption, technology transfer mechanisms, increased robustness in data-tracking and countering external economic shocks. The data presented is not meant to be comprehensive nor complete. Consequently, suggested future work addresses short-term, mid-term, and long-term strategies. Specific areas include examining causal linkages for mobile phone adoption, designing technology initiatives around sustainability goals, and drivers that facilitate technology transfer. Mobile telecommunication technology offers real opportunities for development and growth in Africa. If the focus of development shifts from mere economic growth to sustainable development, countries can not only transform their economic fortunes but also enhance the quality of their environment.<br>by Alexander Shih.<br>S.M.in Engineering and Management, and, in Technology and Policy
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Kwon, Bongkyoung Kwon. "Adaptive frame structure and OFDMA resource allocation in mobile multi-hop relay networks." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2009. http://hdl.handle.net/1853/31818.
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Thesis (Ph.D)--Electrical and Computer Engineering, Georgia Institute of Technology, 2010.<br>Committee Chair: Dr. John A. Copeland; Committee Member: Dr. George F. Riley; Committee Member: Dr. Henry L. Owen; Committee Member: Dr. Mary Ann Ingram; Committee Member: Dr. Patrick Traynor. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Li, Bin. "Bandwidth allocation and call admission control in multi-services mobile wireless cellular networks /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?ELEC%202003%20LI.
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Bria, Aurelian. "Mobile Multimedia Multicasting in Future Wireless Systems : A Hybrid Cellular-Broadcasting System Approach." Doctoral thesis, Stockholm : Informations- och kommunikationsteknik, Kungliga Tekniska högskolan, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-9795.
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Ng, Chi-kwong, and 吳志光. "Location management and level switching schemes in multitier mobile communication systems." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2005. http://hub.hku.hk/bib/B30168661.
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Alparslan, Denizhan N. Sohraby Khosrow. "Modeling and analysis of generalized random mobility models for wireless ad hoc networks." Diss., UMK access, 2005.
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Thesis (Ph. D.)--School of Computing and Engineering. University of Missouri--Kansas City, 2005.<br>"A dissertation in telecommunication networking and computer networking." Advisor: Khosrow Sohraby. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed May 30, 2006. Includes bibliographical references (leaves 119-123). Online version of the print edition.
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Fang, Zuyuan. "Bandwidth allocation in wireless AD HOC networks /." View abstract or full-text, 2004. http://library.ust.hk/cgi/db/thesis.pl?COMP%202004%20FANG.
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Thesis (Ph. D.)--Hong Kong University of Science and Technology, 2004.<br>Includes bibliographical references (leaves 112-119). Also available in electronic version. Access restricted to campus users.
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Kim, Jonghyun. "Realistic mobility modeling and simulation for mobile wireless network in urban environments." Access to citation, abstract and download form provided by ProQuest Information and Learning Company; downloadable PDF file 2.67Mb, 81 p, 2005. http://wwwlib.umi.com/dissertations/fullcit/1428178.
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Bhaduri, Anuket. "User Controlled Privacy Protection in Location-Based Services." Fogler Library, University of Maine, 2003. http://www.library.umaine.edu/theses/pdf/BhaduriA2003.pdf.
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Wong, Yan Chiew. "Impedance matching and DC-DC converter designs for tunable radio frequency based mobile telecommunication systems." Thesis, University of Edinburgh, 2014. http://hdl.handle.net/1842/9656.
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Tunability and adaptability for radio frequency (RF) front-ends are highly desirable because they not only enhance functionality and performance but also reduce the circuit size and cost. This thesis presents a number of novel design strategies in DC-DC converters, impedance networks and adaptive algorithms for tunable and adaptable RF based mobile telecommunication systems. Specifically, the studies are divided into three major directions: (a) high voltage switch controller based DC-DC converters for RF switch actuation; (b) impedance network designs for impedance transformation of RF switches; and (c) adaptive algorithms for determining the required impedance states at the RF switches. In the first stage, two-phase step-up switched-capacitor (SC) DC-DC converters are explored. The SC converter has a simple control method and a reduced physical volume. The research investigations started with the linear and the non-linear voltage gain topologies. The non-linear voltage gain topology provides a higher voltage gain in a smaller number of stages compared to the linear voltage gain topology. Amongst the non-linear voltage gain topologies, a Fibonacci SC converter has been identified as having lower losses and a higher conversion ratio compared to other topologies. However, the implementation of a high voltage (HV) gain Fibonacci SC converter is complex due to the requirement of widely different gate voltages for the transistors in the Fibonacci converter. Gate driving strategies have been proposed that only require a few auxiliary transistors in order to provide the required boosted voltages for switching the transistors on and off. This technique reduces the design complexity and increases the reliability of the HV Fibonacci SC converter. For the linear voltage gain topology, a high performance complementary-metaloxide- semiconductor (CMOS) based SC DC-DC converter has been proposed in this work. The HV SC DC-DC converter has been designed in low voltage (LV) transistors technology in order to achieve higher voltage gain. Adaptive biasing circuits have been proposed to eliminate the leakage current, hence avoiding latch-up which normally occurs with low voltage transistors when they are used in a high voltage design. Thus, the SC DC-DC converter achieves more than 25% higher boosted voltage compared to converters that use HV transistors. The proposed design provides a 40% power reduction through the charge recycling circuit that reduces the effect of non-ideality in integrated HV capacitors. Moreover, the SC DC-DC converter achieves a 45% smaller area than the conventional converter through optimising the design parameters. In the second stage, the impedance network designs for transforming the impedance of RF switches to the maximum achievable impedance tuning region are investigated. The maximum achievable tuning region is bounded by the fundamental properties of the selected impedance network topology and by the tunable values of the RF switches that are variable over a limited range. A novel design technique has been proposed in order to achieve the maximum impedance tuning region, through identifying the optimum electrical distance between the RF switches at the impedance network. By varying the electrical distance between the RF switches, high impedance tuning regions are achieved across multi frequency standards. This technique reduces the cost and the insertion loss of an impedance network as the required number of RF switches is reduced. The prototype demonstrates high impedance coverages at LTE (700MHz), GSM (900MHz) and GPS (1575MHz). Integration of a tunable impedance network with an antenna for frequency-agility at the RF front-end has also been discussed in this work. The integrated system enlarges the bandwidth of a patch antenna by four times the original bandwidth and also improves the antenna return loss. The prototype achieves frequency-agility from 700MHz to 3GHz. This work demonstrates that a single transceiver with multi frequency standards can be realised by using a tunable impedance network. In the final stage, improvement to an adaptive algorithm for determining the impedance states at the RF switches has been proposed. The work has resulted in one more novel design techniques which reduce the search time in the algorithm, thus minimising the risk of data loss during the impedance tuning process. The approach reduces the search time by more than an order of magnitude by exploiting the relationships among the mass spring’s coefficient values derived from the impedance network parameters, thereby significantly reducing the convergence time of the algorithm. The algorithm with the proposed technique converges in less than half of the computational time compared to the conventional approach, hence significantly improving the search time of the algorithm. The design strategies proposed in this work contribute towards the realisation of tunable and adaptable RF based mobile telecommunication systems.
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Kroeker, P. Paul. "Technology to facilitate interaction in mobile learning /." View PDF document on the Internet, 2005. http://library.athabascau.ca/drr/download.php?filename=scis/KroekerPaulEssay.pdf.
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Wang, Xiaodong. "Mobile communications in China an analysis of the diffusion process /." The Ohio State University, 1994. http://catalog.hathitrust.org/api/volumes/oclc/34639588.html.
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Otto, Christiaan Hamman. "The use of systems development methodologies in mobile telecommunication software development in South Africa / C.H. Otto." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1257.
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This study aims to identify the ways in which mobile telecommunications software systems are
developed in practice in South Africa. The main objectives are to identify the systems
development methodologies used, if any, during development, to highlight certain key aspects of
mobile telecommunication software development and identify a list of necessities a systems
development methodology should contain when used to develop mobile telecommunications
software.
In the highly competitive market of mobile telecommunications, it is extremely important that
mobile telecommunications systems are developed in minimal time. with minimal cost while still
ensuring quality and usability. As stated by Fitzgerald (1996), a big factor that could have a
positive impact on the development process is the use of a systems development methodology.
Because of the importance of systems development methodologies, this study identifies and
discusses different types of systems development methodologies from the available literature and
also three systems development methodologies designed specifically for developing mobile
telecommunication systems.
To determine how mobile telecommunication systems arc developed in practice. a qualitative
research method was used. Case studies were done at three different mobile telecommunications
software development companies in South Africa. Data were collected by conducting semi
structured interviews with developers or project managers at each of the companies. Coding of
the data was done with the help of ATLAS.ti and analysed by means of cross-case content
analysis.
It was found that mobile telecommunications software development companies in South Africa
tended to make use of in-house developed systems development methodologies, focusing on
flexibility and speed of development. This was driven by the constant interaction of software
with other telecommunications systems and the speed at which mobile telecommunication
software need to be developed. Key aspects of these in-house systems development
methodologies were identified as well as a list of necessities which should be addressed during
mobile telecommunication system development<br>Thesis (M.Sc. (Computer Science))--North-West University, Potchefstroom Campus, 2007.
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Bohannan, Chad Brian. "Performance evaluation of routing protocols for QOS support in rural mobile ad hoc networks." Thesis, Montana State University, 2008. http://etd.lib.montana.edu/etd/2008/bohannan/BohannanC0508.pdf.
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We evaluate several routing protocols, and show that the use of bandwidth and delay estimation can provide throughput and delay guarantees in Mobile Ad Hoc Networks (MANETs). This thesis describes modifications to the Dynamic Source Routing (DSR) protocol to implement the Quality Aware Source Routing (QASR) network routing protocol operating on an 802.11e link layer. QASR network nodes exchange node location and flow reservation data periodically to provide information necessary to model and estimate both the available bandwidth and the end-to-end delay of available routes during route discovery. Bandwidth reservation is used to provide end-to-end Quality of Service, while also utilizing the differentiated Quality of Service provided by the 802.11e link layer. We show that QASR performs significantly better in several performance metrics over the DSR and the Ad-Hoc On-Demand Distance Vector (AODV) protocols, and performs more consistently in all quality metrics when traffic demand exceeds network capacity.
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Ko, Leonard L. "Personal information system /." Online version of thesis, 1993. http://hdl.handle.net/1850/11976.
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Erasmus, J. M. (Johan Michiel). "Design of a mobile field station for LEO satellite communications." Thesis, Stellenbosch : Stellenbosch University, 2000. http://hdl.handle.net/10019.1/51677.
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Thesis (MEng)--University of Stellenbosch, 2000.<br>ENGLISH ABSTRACT: This document describes the breadboard design and practical evaluation of a mobile
field station, capable of communicating with the SUNSAT micro satellite. A study of
existing satellite communication systems employing LEO satellites, as well as the
physical phenomena, influencing the VHF communication link between earth and
such satellites was done and used to determine the specifications needed for a
functional field station.
The design entailed work on different building blocks like a receiver, transmitter and
modem unit as well as the writing and testing of the necessary software on a
controlling personal computer. The measurements done showed that the field station
satisfies most of the specifications, and that it is capable of communicating with a
satellite. The document is concluded by suggesting improvements and possible further
work before a commercial version of the field station may be build.<br>AFRIKAANSE OPSOMMING: In hierdie dokument word die ontwerp en praktiese evaluasie van 'n mobiele
veldstasie beskryf wat met die SUNSAT mikrosatelliet kan kommunikeer. 'n
Ondersoek na bestaande satellietstelsels in lae-aard wentelbane en die fisiese faktore
wat die radioskakel tussen die grond en sulke satelliete beïnvloed is gebruik om
spesifikasies vir 'n werkende veldstasie daar te stel.
Die ontwerpstaak het werk aan 'n ontvanger, sender, modem en beheerproggramatuur
ingesluit. Die voltooide veldstasie is gekarakteriseer deur 'n meetproses wat
aangetoon het dat dit met 'n satelliet kan kommunikeer. Die dokument word afgesluit
met voorgestelde verbeterings en verdere werk aan die veldstasie voordat 'n
kommersiële weergawe daarvan voltooi kan word.
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Zhang, Mingliu. "Wireless communication for sparse and rural areas." Diss., Montana State University, 2007. http://etd.lib.montana.edu/etd/2007/zhang/ZhangM0807.pdf.
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Terry, John D. "Blind adaptive array techniques for mobile satellite communications." Diss., Georgia Institute of Technology, 1999. http://hdl.handle.net/1853/13425.
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He, Changhua, and 何昌華. "Resource management for handoff control in wireless/mobile networks using artificial neural networks." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2001. http://hub.hku.hk/bib/B31226000.
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Barlow, David A. "Router-based traffic engineering in MPLS/DiffServ/HMIP radio access networks." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15362.
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Gong, Min. "A policy study on the development of the telecommunications equipment manufacturing industry with two empirical studies on mobile data communications service acceptance in China and Hong Kong /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ISMT%202006%20GONG.
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Mihailescu, Patrik 1977. "MAE : a mobile agent environment for resource limited devices." Monash University, School of Network Computing, 2003. http://arrow.monash.edu.au/hdl/1959.1/5805.
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Chiu, Wan Lan. "Competitive analysis : a case study of the mobile telecommunication services industry in Hong Kong." Thesis, University of Macau, 2003. http://umaclib3.umac.mo/record=b1636643.
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Wasinger, Rainer. "Multimodal interaction with mobile devices: fusing a broad spectrum of modality combinations." Berlin Aka, 2006. http://deposit.d-nb.de/cgi-bin/dokserv?id=2890796&prov=M&dok_var=1&dok_ext=htm.
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Baig, Adeel Computer Science & Engineering Faculty of Engineering UNSW. "Improving throughput and fairness of on-board mobile networks." Awarded by:University of New South Wales. School of Computer Science & Engineering, 2007. http://handle.unsw.edu.au/1959.4/28247.
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The Internet Engineering Task Force (IETF) has recently released network mobility standards that allow deployment of TCP/IP networks onboard a vehicle and maintain permanent network connectivity to the Internet via a vehicular mobile router. This recent development opens up new opportunities for providing efficient mobile computing for users on the move, especially for commuters traveling on public transports. Moreover, central and coordinated management of mobility in a single router, rather than by each user device individually, has numerous advantages. In this architecture, however, it becomes challenging to guarantee network performance due to the mobility of the network and inherently vulnerable nature of wireless links. In this thesis, a detailed performance study of onboard networks is conducted. It has been shown that disruptions in the mobile router connectivity can significantly degrade network throughput. Moreover, factors such as the limited wireless bandwidth of the access link, variations in the bandwidth due to technology switching, and the communication diversity of onboard users all contribute to the problem of unfair sharing of wireless bandwidth. By leveraging the fact that all onboard communications go through the mobile router, performance enhancing solutions are proposed that can be deployed in the mobile router to transparently address the throughput and fairness problems. In this architecture, when the route is known in advance and repetitive (e.g. for public transport or a regularly commuting private vehicle), a certain degree of prediction of impending link disruptions is possible. An anticipatory state freezing mechanism is proposed that relies on the prediction of link disruptions to freeze and unfreeze the state machine of TCP, the widely used transport protocol in the Internet. Simulation study shows that TCP throughput has a non-linear relationship with the prediction accuracy. As prediction accuracy increases, throughput problem diminishes quickly. An adaptive mobile router based fairness control mechanism is proposed to address the unfair sharing of wireless bandwidth in highly dynamic scenarios. The fairness is controlled by dynamically estimating the round-trip-times of all onboard TCP connections and transparently adjusting the protocol control parameters at the router. The thesis also discusses implementation issues for the proposed solutions.
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Cornillet, Nicolas. "Convergence des réseaux de télécommunications mobiles et de télédiffusion : modélisation et évaluation des performances d’un réseau hybride LTE/DVB-T2." Thesis, Rennes, INSA, 2013. http://www.theses.fr/2013ISAR0034/document.
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Ces dernières années, la popularité croissante de terminaux mobiles de plus en plus intelligents a provoqué une hausse considérable du trafic supporté par les réseaux de télécommunications cellulaires. Dans ce contexte, le déploiement de réseaux dits de quatrième génération basés sur le standard LTE (Long Term Evolution) et offrant des capacités significativement plus élevées que les réseaux de générations précédentes peut sembler être une solution idéale. Cependant, dans le cas d’un service à délivrer à un très grand nombre d’utilisateurs, ce standard, malgré la disponibilité de la technologie eMBMS (Evolved Multimedia Broadcast Multicast Services), n’est pas forcément le plus adapté. Dans le même temps, la télévision a achevé dans de nombreux pays sa transition vers le numérique. L’abandon de la transmission analogique a permis non seulement d’améliorer la qualité du service mais aussi d’occuper moins de spectre. En France, une partie du spectre libéré a déjà été attribué au déploiement de réseaux LTE. Une autre méthode permettant d’exploiter ce spectre au profit des réseaux de communications mobiles est proposée dans cette thèse : le réseau hybride. Le réseau hybride est constitué d’un réseau cellulaire au standard LTE accompagné d’un émetteur DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial). Les aires de couverture de ces deux composantes se superposent et un service peut être transmis aux utilisateurs présents dans ces aires indifféremment par l’une ou l’autre des composantes. Ce concept permet de pallier un point faible du standard LTE, c’està- dire la capacité à délivrer efficacement un même service à un grand nombre d’utilisateurs simultanément. Après une étude approfondie des deux standards utilisés, un modèle mathématique du réseau hybride est proposé. Ce modèle se base sur les propriétés géométriques du réseau hybride, les performances des deux types de signaux utilisés, et sur plusieurs types de répartition des utilisateurs pour évaluer les performances du réseau hybride selon différents critères. Le premier critère étudié est un critère énergétique. Le modèle proposé permet de comparer les efficacités énergétiques des deux composantes pour transmettre un service en fonction de son nombre d’utilisateurs. L’efficacité de la composante DVBT2 dépasse celle de la composante LTE à partir d’un seuil dont la valeur varie avec les propriétés géométriques du réseau et le type d’affaiblissement de propagation auquel sont soumis les signaux. Il est de plus possible, dans certaines circonstances, d’améliorer encore l’efficacité énergétique du système en utilisant conjointement les deux composantes. Le second critère étudié est celui de l’encombrement du réseau cellulaire. En effet, un service consommé par un grand nombre d’utilisateurs peut avoir un impact conséquent sur le trafic à transmettre par un réseau LTE. Utiliser la composante DVB-T2 pour distribuer un tel service permet de réduire la charge du réseau cellulaire, et ceci même dans le cas où la composante DVB-T2 ne couvre pas l’ensemble de la zone à desservir globalement. Ces différentes études ont permis de bien mettre en évidence les avantages et inconvénients des deux types de réseaux broadcast et unicast. En particulier, l’intérêt d’une approche reposant sur l’utilisation d’un réseau hybride exploitant la complémentarité des deux composantes broadcast et unicast a été démontré<br>During the last few years, the growing popularity of smarter and smarter mobile devices has led to a tremendous growth of cellular data traffic. In such a context, the deployment of fourth generation networks based on the LTE (Long Term Evolution) standard and with capacities significantly higher than previous generations networks can be seen as an ideal solution. However, when the number of users requiring a given service is large, this standard, despite the availability of the eMBMS (Evolved Multimedia Broadcast Multicast Services) technology, is not necessarily the most suitable. Meanwhile, television has completed its transition to the digital transmission in many countries. The analog switch-off has not only allowed a better quality of service but has also freed some spectrum. In France, some of this spectrum has already been used for the deployment of LTE networks. This thesis introduces another way to use this spectrum to the benefit of mobile data networks: the hybrid network. The hybrid network consists of a LTE cellular network and a DVB-T2 (Digital Video Broadcasting – Second Generation Terrestrial) transmitter. The coverage areas of the two components are overlapping and a service can be delivered to the users located in these areas by either one or the other of the components. This concept can compensate one weakness of the LTE standard, which is the ability to deliver efficiently the same service to a large number of users simultaneously. After a thorough study of the two standards in use, a mathematical model of the hybrid network is proposed. This model is based on the geometrical properties of the network, the performances of the two types of signal, and different types of users distribution to measure the performances of the hybrid network using different criteria. The first criterion is the energy efficiency. The proposed model allows the comparison of the two components in terms of energy efficiency for one service depending of the number of its users. The DVB-T2 component outperforms the LTE component when the number of users exceeds a given threshold whose value depends on the geometric properties of the network and the type of path loss attenuating the signals. It is possible, in some cases, to further improve the energy efficiency of the system by using both components together. The second criterion is the network congestion. Indeed, a service with a great number of users can induce significant data traffic for the LTE network. Transmitting such a service through the DVB-T2 component can decrease the cellular data traffic even if the DVB-T2 component does not cover the whole area of interest. These studies have brought out the benefits and drawbacks of both broadcast and unicast networks. Especially, the interest of the hybrid network based on the complementarities between the two components has been demonstrated
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Cloppenburg, Jürgen. "The regulation of global mobile personal communications by satellite : a comparative analysis of regulations, policy and perspectives in the European Union, in particular Germany, and the United States." Thesis, McGill University, 2000. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=31153.
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This thesis analyses the current regulatory regimes in the European Union---in particular Germany---and the United States governing the authorization of global mobile personal communications by satellite (GMPCS).<br>Current satellite licensing regimes fail to take into account the international character of satellite telecommunications. The reliance on a national public interest standard does not properly address the interests of the community of states, industry and consumers and is not suitable to meet the aspirations of international space law. The international harmonization of frequencies and international standardization are indispensable for the introduction of these new services. The establishment of an international communications regulator with the power to adopt binding decisions if required is the most suitable way to address these problems. However, the development of an international public interest standard with clear policy objectives will be hard to achieve.<br>With regard to the different aspects of ground segment licensing, a gradual approach is the best way to balance the different interests and concerns in this field. The International Telecommunications Union GMPCS MoU and the development of European regulations show a feasible way to achieve a regulatory regime that facilitates the introduction of these new services. Lighter regulations, possibly the introduction of one stop shopping procedures, mutual recognition of licenses and the introduction of general authorizations are measures that can and should be taken at the international level. The interdependence of earth and space segment licensing may lead to the understanding that some aspects of earth segment licensing should also be regulated at international level.<br>The question will be whether States, industry and users are able to reconcile their interests and the sometimes opposing trends of international cooperation and international competition for the benefit of "all mankind".
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Yip, Hoi-kit, and 葉海傑. "Packet scheduling techniques for coordinating colocated Bluetooth and IEEE 802.11b in a Linux machine." Thesis, The University of Hong Kong (Pokfulam, Hong Kong), 2004. http://hub.hku.hk/bib/B29727285.
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Bradley, W. Scott. "Propagation modeling for land mobile satellite communications." Thesis, Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/74511.
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Satellite systems are being planned for two-way communication with mobile vehicles using UHF and L-band frequencies. Of special concern in the system design are the characteristics of propagation in suburban and rural areas where fading occurs due to multipath effects and vegetative shadowing. A review of the literature was performed to study these propagation impairments. Available experimental data are examined, compared, and summarized. Propagation through vegetation is studied in order to compare reported modeling efforts and to determine the parameter dependences of path loss. A simple deterministic path model is then presented to estimate vegetative path loss. An overall statistical model is also proposed to describe the signal level fading statistics. The statistical model is compared to data, and the deterministic path model is used to determine the mean of signal level distribution functions in the presence of shadowing.<br>Master of Science
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Viljoen, Johannes Henning. "Modelling and optimal control of the market of a telecommunications operator." Diss., Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-09152004-100823.
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Di, Caro Gianni. "Ant colony optimization and its application to adaptive routing in telecommunication networks." Doctoral thesis, Universite Libre de Bruxelles, 2004. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211149.
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In ant societies, and, more in general, in insect societies, the activities of the individuals, as well as of the society as a whole, are not regulated by any explicit form of centralized control. On the other hand, adaptive and robust behaviors transcending the behavioral repertoire of the single individual can be easily observed at society level. These complex global behaviors are the result of self-organizing dynamics driven by local interactions and communications among a number of relatively simple individuals.<p><p>The simultaneous presence of these and other fascinating and unique characteristics have made ant societies an attractive and inspiring model for building new algorithms and new multi-agent systems. In the last decade, ant societies have been taken as a reference for an ever growing body of scientific work, mostly in the fields of robotics, operations research, and telecommunications.<p><p>Among the different works inspired by ant colonies, the Ant Colony Optimization metaheuristic (ACO) is probably the most successful and popular one. The ACO metaheuristic is a multi-agent framework for combinatorial optimization whose main components are: a set of ant-like agents, the use of memory and of stochastic decisions, and strategies of collective and distributed learning.<p><p>It finds its roots in the experimental observation of a specific foraging behavior of some ant colonies that, under appropriate conditions, are able to select the shortest path among few possible paths connecting their nest to a food site. The pheromone, a volatile chemical substance laid on the ground by the ants while walking and affecting in turn their moving decisions according to its local intensity, is the mediator of this behavior.<p><p>All the elements playing an essential role in the ant colony foraging behavior were understood, thoroughly reverse-engineered and put to work to solve problems of combinatorial optimization by Marco Dorigo and his co-workers at the beginning of the 1990's.<p><p>From that moment on it has been a flourishing of new combinatorial optimization algorithms designed after the first algorithms of Dorigo's et al. and of related scientific events.<p><p>In 1999 the ACO metaheuristic was defined by Dorigo, Di Caro and Gambardella with the purpose of providing a common framework for describing and analyzing all these algorithms inspired by the same ant colony behavior and by the same common process of reverse-engineering of this behavior. Therefore, the ACO metaheuristic was defined a posteriori, as the result of a synthesis effort effectuated on the study of the characteristics of all these ant-inspired algorithms and on the abstraction of their common traits.<p><p>The ACO's synthesis was also motivated by the usually good performance shown by the algorithms (e.g. for several important combinatorial problems like the quadratic assignment, vehicle routing and job shop scheduling, ACO implementations have outperformed state-of-the-art algorithms).<p><p>The definition and study of the ACO metaheuristic is one of the two fundamental goals of the thesis. The other one, strictly related to this former one, consists in the design, implementation, and testing of ACO instances for problems of adaptive routing in telecommunication networks.<p><p>This thesis is an in-depth journey through the ACO metaheuristic, during which we have (re)defined ACO and tried to get a clear understanding of its potentialities, limits, and relationships with other frameworks and with its biological background. The thesis takes into account all the developments that have followed the original 1999's definition, and provides a formal and comprehensive systematization of the subject, as well as an up-to-date and quite comprehensive review of current applications. We have also identified in dynamic problems in telecommunication networks the most appropriate domain of application for the ACO ideas. According to this understanding, in the most applicative part of the thesis we have focused on problems of adaptive routing in networks and we have developed and tested four new algorithms.<p><p>Adopting an original point of view with respect to the way ACO was firstly defined (but maintaining full conceptual and terminological consistency), ACO is here defined and mainly discussed in the terms of sequential decision processes and Monte Carlo sampling and learning.<p><p>More precisely, ACO is characterized as a policy search strategy aimed at learning the distributed parameters (called pheromone variables in accordance with the biological metaphor) of the stochastic decision policy which is used by so-called ant agents to generate solutions. Each ant represents in practice an independent sequential decision process aimed at constructing a possibly feasible solution for the optimization problem at hand by using only information local to the decision step.<p>Ants are repeatedly and concurrently generated in order to sample the solution set according to the current policy. The outcomes of the generated solutions are used to partially evaluate the current policy, spot the most promising search areas, and update the policy parameters in order to possibly focus the search in those promising areas while keeping a satisfactory level of overall exploration.<p><p>This way of looking at ACO has facilitated to disclose the strict relationships between ACO and other well-known frameworks, like dynamic programming, Markov and non-Markov decision processes, and reinforcement learning. In turn, this has favored reasoning on the general properties of ACO in terms of amount of complete state information which is used by the ACO's ants to take optimized decisions and to encode in pheromone variables memory of both the decisions that belonged to the sampled solutions and their quality.<p><p>The ACO's biological context of inspiration is fully acknowledged in the thesis. We report with extensive discussions on the shortest path behaviors of ant colonies and on the identification and analysis of the few nonlinear dynamics that are at the very core of self-organized behaviors in both the ants and other societal organizations. We discuss these dynamics in the general framework of stigmergic modeling, based on asynchronous environment-mediated communication protocols, and (pheromone) variables priming coordinated responses of a number of ``cheap' and concurrent agents.<p><p>The second half of the thesis is devoted to the study of the application of ACO to problems of online routing in telecommunication networks. This class of problems has been identified in the thesis as the most appropriate for the application of the multi-agent, distributed, and adaptive nature of the ACO architecture.<p><p>Four novel ACO algorithms for problems of adaptive routing in telecommunication networks are throughly described. The four algorithms cover a wide spectrum of possible types of network: two of them deliver best-effort traffic in wired IP networks, one is intended for quality-of-service (QoS) traffic in ATM networks, and the fourth is for best-effort traffic in mobile ad hoc networks.<p><p>The two algorithms for wired IP networks have been extensively tested by simulation studies and compared to state-of-the-art algorithms for a wide set of reference scenarios. The algorithm for mobile ad hoc networks is still under development, but quite extensive results and comparisons with a popular state-of-the-art algorithm are reported. No results are reported for the algorithm for QoS, which has not been fully tested. The observed experimental performance is excellent, especially for the case of wired IP networks: our algorithms always perform comparably or much better than the state-of-the-art competitors.<p><p>In the thesis we try to understand the rationale behind the brilliant performance obtained and the good level of popularity reached by our algorithms. More in general, we discuss the reasons of the general efficacy of the ACO approach for network routing problems compared to the characteristics of more classical approaches. Moving further, we also informally define Ant Colony Routing (ACR), a multi-agent framework explicitly integrating learning components into the ACO's design in order to define a general and in a sense futuristic architecture for autonomic network control.<p><p>Most of the material of the thesis comes from a re-elaboration of material co-authored and published in a number of books, journal papers, conference proceedings, and technical reports. The detailed list of references is provided in the Introduction.<p><p><p><br>Doctorat en sciences appliquées<br>info:eu-repo/semantics/nonPublished
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Rao, Sira. "Elastic Algorithms for Region of Interest Video Compression, with Application to Mobile Telehealth." Diss., Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19881.
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Video is the most demanding modality from the viewpoints of bandwidth, computational complexity, and resolution. Thus, there has been limited progress in the field of mobile video technology. In the research, the focus is on elastic wireless video technology, and its adaptation to diagnostic application requirements in real-time clinical assessment. It is important and timely to apply wireless video technology to real-time remote diagnosis of emergent medical events. This premise comes from initial successes in telehealth based on wired networks. The enablement of mobility (for the physician and/or the patient) by wireless communication will be a next major step, but this advance will depend on definitive and compelling demonstrations of reliability. Thus, an important goal of the research is to develop a complete methodology that will be embraced by physicians. Acute pediatric asthma has been identified as a domain where this new capability will be highly welcome.
The research uses flexible and interactive algorithms for Region-of-Interest (ROI) processing. ROI processing is a useful approach to achieve the optimal balance in the quality-bandwidth tradeoff characteristic of visual communication services. The notion of ROI has been traditionally used mostly for foreground-background separation in scene rendering and manipulation, and only more recently for variably quality compression. Even when the latter goal is considered, quality criteria have been ad-hoc and at best useful for video conferencing, given that the medical domain has its own fidelity criteria. The research thus focuses on the design of an elastic ROI-based compression paradigm with medical diagnosis as a central criterion.
The research describes the methodology to achieve elasticity through rate control algorithms at the encoder. An elastic non-parametric approach is proposed that uses a priori user-specified video quality information, quantifies this information, and incorporates this into the encoder in the form of region-quality mappings. This method is compared to a parametric bit allocation approach that is based on region-features and a set of tuning weights. A number of videos of actual patients were filmed and used as the video database for the developed algorithms. In testing the elastic non-parametric and parametric algorithms, both objective measures in the form of Peak Signal to Noise Ratio (PSNR), and subjective evaluations were used. Thus, in this work, the focus is on domain relevance of the algorithms developed, as opposed to network related issues such as packet losses. This is justified in that these may have broader value with other applications, and continuation of this work will include realistic network conditions. To summarize, the research shows the usefulness of ROI processing as a means of achieving a gain (in a bits per pixel sense) over uniform compression at the same bitrate. It also shows how quantifying a notion of functionally lossless video quality diagnostically lossless video quality in a video-based telehealth system, in a bits per pixel sense is useful from an applications and bitrate perspective. Finally, a combination of these two concepts is advantageous i.e. diagnostically lossless ROI video quality is achievable over bitrate limited channels.
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Piovezani, Larissa 1987. "Simulação de serviços multimídia em redes de acesso de banda larga móvel = Multimedia services simulation on mobile broadband networks." [s.n.], 2013. http://repositorio.unicamp.br/jspui/handle/REPOSIP/267763.
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Orientador: Varese Salvador Timóteo<br>Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Tecnologia<br>Made available in DSpace on 2018-08-22T06:38:08Z (GMT). No. of bitstreams: 1
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Previous issue date: 2013<br>Resumo: Este projeto consiste no desenvolvimento de um modelo de simulação para serviços multimídia em redes móveis de terceira geração. Inicialmente foram simulados serviços de voz com diferentes cenários de tráfego e posteriormente serviços de dados e vídeo. Para o trabalho foi considerado que o núcleo da rede atende à demanda de acesso, de modo que é necessário modelar apenas a interação entre os terminais móveis e a rede de acesso por rádio. A validação do modelo de simulação foi feita tentando descrever o acesso em redes reais, por exemplo, usando como referência valores estimados para o número de tentativas de chamadas no cenário de pior caso (Busy Hour Call Attempts). As simulações foram realizadas por eventos discretos, baseadas em variáveis aleatórias e métodos de Monte Carlo. O software ARENA, projetado exatamente para este tipo de modelo, foi utilizado nas simulações, já que o sistema em questão tem sua operação baseada em serviços cujos intervalos de requisição e durações podem ser representadas por distribuições conhecidas<br>Abstract: This project develops a simulation model for multimedia services of the third generation mobile network. Initially it was simulated voice services with different traffic scenarios and later video and data services. For this assignment was considered that the core of the network achieves the access demands, thus it is only necessary to model the interaction between the mobile terminal and the radio access network. The validation of the simulation model was done in order to describe the real network access, e.g., estimated values were used as reference for the number of call attempts in the worst case scenario (Busy Hour Call Attempts). The simulations were carried out by discrete events based on random variables and Monte Carlo methods. The ARENA software, designed exactly for this type of model, was used in the simulations because this system has its operation based on services whose request intervals and durations of the system can be represented by known distributions<br>Mestrado<br>Tecnologia e Inovação<br>Mestre em Tecnologia
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Yuen, Kwan Hung. "TCP performance over satellite networks /." View Abstract or Full-Text, 2003. http://library.ust.hk/cgi/db/thesis.pl?COMP%202003%20YUEN.
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Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2003.<br>Includes bibliographical references (leaves 68-71). Also available in electronic version. Access restricted to campus users.
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Axelsson, Karin, and Cynthia Novak. "Support for Cell Broadcast as Global Emergency Alert System." Thesis, Linköping University, Department of Science and Technology, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-9491.
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<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>
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Kakumanu, Sandeep. "Component Based Channel Assignment in Single Radio, Multichannel Ad hoc Networks." Thesis, Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/19870.
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In this work, we consider the channel assignment problem in single radio multi-channel mobile ad-hoc networks. Specifically, we investigate the granularity of channel assignment decisions that gives the best trade-off in terms of performance and complexity. We present a new granularity for channel assignment that we refer to as component level channel assignment. The strategy is relatively simple, and is characterized by several impressive practical advantages. We also show that the theoretical performance of the component based channel assignment strategy does not lag significantly behind the optimal possible performance, and perhaps more importantly we show that when coupled with its several practical advantages, it significantly outperforms other strategies under most network conditions.
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Basole, Rahul C. "Modeling and Analysis of Complex Technology Adoption Decisions: An Investigation in the Domain of Mobile ICT." Diss., Available online, Georgia Institute of Technology, 2006, 2006. http://etd.gatech.edu/theses/available/etd-06162006-142751/.
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Thesis (Ph. D.)--Industrial and Systems Engineering, Georgia Institute of Technology, 2007.<br>Rouse, William, Committee Chair ; DeMillo, Richard, Committee Member ; Cross, Steve, Committee Member ; Cummins, Michael, Committee Member ; Vengazhiyil, Roshan, Committee Member.
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Haenssgen, Marco Johannes. "Mobile phone diffusion and rural heathcare access in India and China." Thesis, University of Oxford, 2015. https://ora.ox.ac.uk/objects/uuid:3f48fc8b-5414-4851-926b-07a57eed6cfe.
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Three decades of mobile phone diffusion, thousands of mobile-phone-based health projects worldwide ("mHealth"), and tens of thousands of health applications in Apple's iTunes store, but fundamental questions about the effect of phone diffusion on people's healthcare behaviour remain unanswered. Empirical, theoretical, and methodological gaps in the study of mobile phones and health reinforce each other and lead to simplifying assumptions that mobile phones are a ubiquitous and neutral platform for interventions to improve health and healthcare. This contradicts what we know from the technology adoption literature. This thesis explores the theoretical link between mobile phone diffusion and healthcare access; develops and tests a new multidimensional indicator of mobile phone adoption; and analyses the effects of phone use on people's healthcare-seeking behaviour. My mixed methods research design - implemented in rural Rajasthan (India) and Gansu (China) - involves qualitative research with 231 participants and primary survey data from 800 persons. My research yields a qualitatively grounded framework that describes the accessibility and suitability of mobile phones in healthcare-seeking processes, the heterogeneous outcomes of phone use and non-use on healthcare access, and the uneven equity consequences in this process. Quantitative analysis based on the framework finds that mobile phone use in rural India and China increases access to healthcare, but it also invites more complex and delayed health behaviours and the over-use of scarce healthcare resources. Moreover, increasing phone-aided health action threatens to marginalise socio-economically disadvantaged groups further. I present here the first quantitative evidence on how mobile phone adoption influences healthcare-seeking behaviour. This challenges the common view that mHealth interventions operate on a neutral platform and draws attention to potential targeting, user acceptance, and sustainability problems. The framework and tools developed in this thesis can support policy considerations for health systems to evaluate and address the healthcare implications of mobile phone diffusion.
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Salmon, Brian P. "Optimizing LDPC codes for a mobile WiMAX system with a saturated transmission amplifier." Pretoria : [s.n.], 2008. http://upetd.up.ac.za/thesis/available/etd-01262009-160431/.
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Wu, Hao. "Analysis and Design of Vehicular Networks." Diss., Georgia Institute of Technology, 2005. http://hdl.handle.net/1853/7639.
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Advances in computing and wireless communication technologies have increased interest in smart vehicles, vehicles equipped with significant computing, communication and sensing capabilities to provide services to travelers. Smart vehicles can be exploited to improve driving safety and comfort as well as optimize surface transportation systems. Wireless communications among vehicles and between vehicles and roadside infrastructures represent an important class of vehicle communications.
One can envision creating an integrated radio network leveraging various wireless technologies that work together in a seamless fashion. Based on cost-performance tradeoffs, different network configurations may be appropriate for different environments. An understanding of the properties of different vehicular network architectures is absolutely necessary before services can be successfully deployed. Based on this understanding, efficient data services (e.g., data dissemination services) can be designed to accommodate application requirements.
This thesis examines several research topics concerning both the evaluation and design of vehicular networks.
We explore the properties of vehicle-to-vehicle (v2v) communications. We study the spatial propagation of information along the road using v2v communications. Our analysis identifies the vehicle traffic characteristics that significantly affect information propagation. We also evaluate the feasibility of propagating information along a highway.
Several design alternatives exist to build infrastructure-based vehicular networks. Their characteristics have been evaluated in a realistic vehicular environment. Based on these evaluations, we have developed some insights into the design of future broadband vehicular networks capable of adapting to varying vehicle traffic conditions.
Based on the above analysis, opportunistic forwarding that exploit vehicle mobility to overcome vehicular network partitioning appears to be a viable approach for data dissemination using v2v communications for applications that can tolerate some data loss and delay. We introduce a methodology to design enhanced opportunistic forwarding algorithms. Practical algorithms derived from this methodology have exhibited different performance/overhead tradeoffs.
An in-depth understanding of wireless communication performance in a vehicular environment is necessary to provide the groundwork for realizing reliable mobile communication services. We have conducted an extensive set of field experiments to uncover the performance of short-range communications between vehicles and between vehicles and roadside stations in a specific highway scenario.
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Choi, Gi Wan. "Low-complexity and power-efficient wireless cooperative relay networks with enhanced reliability." Diss., Georgia Institute of Technology, 2013. http://hdl.handle.net/1853/47721.
Full textAbstract:
In recent years, global mobile data traffic has been increasing exponentially as mobile devices pervade our daily lives. To cope with the ever growing demands for higher data rates and seamless connectivity, one solution is to drastically increase the number of macro base stations in the conventional cellular architecture. However, this results in high deployment costs. Deploying low-power nodes such as relays that do not require a wired backhaul connection within a macrocell is one of cost-effective ways to extend high data rate coverage range. Relays are typically deployed to increase signal strength in poor coverage areas or to eliminate dead spots. But more importantly, relays provide a natural diversity, called cooperative diversity. In addition to a direct signal from a base station, extra copies of the same signal are forwarded from relays. Utilizing this diversity at the destination can yield significant performance enhancements. Thus, cooperative relay strategies need to be considered to enable high data rate coverage in a cost-effective manner.
In this dissertation, we consider a simple single-relay network and present low-complexity and power-efficient cooperative relay designs that can achieve low error rate. We first study decode-and-forward (DF) relay networks with a single antenna at each node, where the relay decodes the received signal and forwards the re-encoded information to the destination. In DF relay scheme, decoding at the relay is not perfect and the error-propagation phenomenon is a detrimental problem, preventing the destination from collecting the cooperative diversity. To enable cooperative diversity in DF relay networks, we adopt link-adaptive power-scaling relay strategies where the relay scales the transmission power of the re-encoded signal based on the reliability of the source-relay link. We generalize power-profile designs and analyze the diversity order enabled by the general power-profile designs. We provide necessary and sufficient conditions for the designs to enable full cooperative diversity at the destination.
In the second part of this dissertation, we extend the power-scaling relay strategy to DF multi-input multi-output (MIMO) relay networks, where multiple antennas are adopted at each node, and show that full cooperative diversity can also be achieved here. To collect spatial diversity provided by multiple antennas without using maximum-likelihood equalizers (MLEs) or near-ML detectors which exhibit high complexity, channel-controlled automatic repeat request (CC-ARQ) scheme is developed for DF MIMO relay networks to enable spatial diversity with linear equalizers (LEs) maintaining low-complexity. We also show that joint cooperative and spatial diversity can be achieved at the destination when the power-scaling strategy and the CC-ARQ with LEs are combined.
Finally, amplify-and-forward (AF) MIMO relay designs, where the relay simply amplifies the received signal and forwards it to the destination, are studied with consideration of peak-power constraints at the relay. One practical concern for AF relaying is that the output signal at the relay may suffer from large peak-to-average power ratio (PAR), which may cause nonlinear distortion and/or saturation in the transmitted signal due to the limited linear range of power amplifiers. Thus, we first investigate peak-power constrained power-scaling strategies and find a sufficient condition to enable joint cooperative and spatial diversity at the destination. Based on this study, we propose simple and practical AF MIMO relay designs with peak-power constraint at the relay. CC-ARQ is also applied to AF MIMO relay networks to reduce the decoding complexity.