In the recent past, wireless sensor technology has undergone advancements in its autonomous data collecting aspects, and has become an area worth investigating in relation to structural monitoring applications. The system described in this thesis aims at acquiring, storing and displaying overhead transmission line related data collected from a wireless sensor network. Open source tools were used in its development and implementation. The inherent linearly aligned topology of transmission line monitoring devices is not without shortcomings; hence analysis of linear node placement, hardware and software components was carried out to determine the feasibility of the system. Their limited data processing capabilities has motivated the development of a post processing wireless sensor application in order to present any collected structural data in an understandable format.

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This diploma thesis deals with analysis, modeling and simulation of the IEEE 802.11af wireless communication system on the physical layer. When designing the solution, it is necessary to understand in details the features and specifics of the IEEE 802.11af system. The work is primarily describes the transmitting part of the communication system with emphasis on processing IEEE 802.11af signal. Subsequently the block diagram and the basic model are created for the transmitting and receiving parts in SISO and MISO broadcast modes. The model is implemented with graphical user interface in the MATLAB programming environment. This application is used to explore the features and performance of the IEEE 802.11af based on its system parameters. System parameters are user configurable what allows to simulate different scenarios. The application also supports simulation of fading channel.

This paper describes a solution which enables mobile devices to transparently access the campus network and the Internet. Different user classes are provided, and security issues are taken into account. The requirements for user machines are low, and the software is nearly maintenance-free for the network administrator after installation and configuration. / Diese Arbeit realisiert einen transparenten Zugang zum Campusnetz der TU Chemnitz und zum Internet für mobile Geräte. Dabei werden mehrere Nutzerklassen unterschieden und Sicherheitsaspekte berücksichtigt. Die Anforderungen an die Nutzerrechner sind gering, und der Aufwand für den Administrator beschränkt sich im wesentlichen auf die Installation und Konfiguration der Software.

The focus of this thesis is on transferring data between mobile devices. It analyzes the resource consumption of using the Wireless LAN interface in some situations, and proposes and evaluates some new applications involving the transfer of voice and data files. Measurements show the high consumption of battery power due to the operation of a wireless network interface, even if it is not “actively” used to transfer data, while the memory consumption of the running applications is very limited. This thesis includes also an application to transfer files between two or more Pocket PCs: it is proposed as an addition to the VoIP application Minisip. Finally I have developed an application in order to explore the possibility to make a voice call by transferring real-time encoded text using UDP and/or RTP streams. This could be used together with speech-to-text and text-to-speech conversion applications at the end points to allow a “voice conversation” even on wireless links with very limited capacity, whereas a standard VoIP conversation would not be affordable. / Fokus i detta examensarbete ligger på överföring av data mellan mobila enheter. Det analyserar resursutnyttjandet vid användande av Wireless LAN-anslutning i några situationer, samt brukar analysen för att föreslå och utvärdera ett antal nya applikationer för överföring av röstsamtal och filer. Mätningar visar den höga konsumtion av batterikraft som anslutning till ett trådlöst nätverk gränsnitt, även då det inte används "aktivt" för dataöverföring, medan de applikationer som använts här behöver bara mycket begränsad minneskapacitet. I detta examensarbete ingår även ett program för överföring av filer mellan två eller flera mobila apparater, föreslaget att ingå i Minisip, en VoIP applikation. Dessutom föreslås och utvärderas en applikation som undersöker möjligheterna att vid röstsamtal överföra realtidskodad text via RTP och/eller UDP stream. Använd tillsammans med en röst-till-text- och text-till-röstomvandling i ändpunkterna möjliggör denna genomförande av röstsamtal även då mycket begränsade trådlösa anslutningar nyttjas. / <p>Exchange student from Pisa.</p>

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第18623号 / 情博第547号 / 新制||情||97(附属図書館) / 31523 / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 守倉 正博, 教授 高橋 達郎, 教授 梅野 健 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(情報学) / 甲第21219号 / 情博第672号 / 新制||情||116(附属図書館) / 京都大学大学院情報学研究科通信情報システム専攻 / (主査)教授 守倉 正博, 教授 原田 博司, 教授 大木 英司 / 学位規則第4条第1項該当 / Doctor of Informatics / Kyoto University / DFAM

<p>Wireless LAN (WLAN) mesh networks are now being used to deploy Wi-Fi coverage in a wide variety of outdoor applications. In these types of networks, conventional WLAN mesh nodes must be operated using continuous electrical power connections. This requirement may often be very expensive, especially when the network includes expansive outdoor wireless coverage areas. An alternative is to operate some of the WLAN mesh nodes using an energy sustainable source such as solar or wind power. This eliminates the need for a fixed power connection, making the node truly tether-less and allowing for more flexibility in node positioning. The cost of the battery and the solar panel or wind turbine can be a significant fraction of the total node cost, therefore the resource allocation must be performed optimally.</p><p>In this thesis we investigate this problem. First, we present geographic provisioning results for solar and wind powered WLAN mesh nodes. The results suggest that in certain geographic locations a hybrid wind/solar powered WLAN mesh node is the optimum minimum cost configuration. The results also provide strong motivation for introducing power saving to the IEEE 802.11 standard. We then consider the problem of cost-optimal node placement in a hybrid network containing traditional and energy sustainable nodes. Our results show that there is a significant improvement in cost that can be obtained using the proposed methodology. Finally, we consider the problem of energy management in these networks. A control algorithm is proposed that uses access to publicly available meteorological databases. We show that the proposed algorithm minimizes node outage and performs favorably compared to the analytic performance bounds. Overall, the work in this thesis develops analytical and simulation models which investigate the key aspects pertaining to resource allocation in energy sustainable WLAN mesh networks.</p> / Thesis / Doctor of Philosophy (PhD)

Mobile handset manufacturers have begun to include wireless LAN (WLAN) interfaces in their cellular handsets. This allows users to access WLAN networks when they are available and to revert to conventional cellular communications otherwise. In this way the handset can dynamically use the "best" available network, by switching connections between the two network interfaces. This switching is referred to as a vertical handoff (VHO). When handling real-time connections, handsets must be capable of performing a seamless vertical handoff. This occurs when the interface switching does not disrupt the quality of service requirements of the active connections. Vertical handoffs are generally time consuming, and this delay creates a difficult problem since WLAN coverage can be lost very abruptly. In this thesis, we propose and investigate several methods of mitigating this problem. A solution based on using a Vertical Handoff Support Node (VHSN) is proposed. When the WLAN link is lost, the VHSN is able to quickly redirect packets through the local cellular base-station during the time that handoff is taking place. This approach can eliminate VHO link loss. It is shown that the act of WLAN-to-cellular handoff can result in a severe bandwidth deficit problem on the WLAN. A novel bandwidth reservation and securing mechanism is proposed which overcomes this problem and performs significantly better than schemes based on modified versions of the static guard channel scheme used in cellular networks. The work is characterized by simulation and analytic models which investigate the key performance aspects of this type of system. / Thesis / Doctor of Philosophy (PhD)

No description available.