Eli Gafni and Dimitri Bertsekas. / Caption title. "August 1982." / Bibliography: leaf 5. / Supported by Defense Advanced Research Projects Agency under Contract no. ONR/N00014-75-C-1183 Program Code no. 5T10

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Thesis (MEng)--University of Stellenbosch, 2000. / 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. / 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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New wireless communication technology standards are being released every year. Wireless technologies merely differ from one another by their range and speed and can each be selected according to the type of application in use. Mobility and ubiquity are the main benefits that can be extracted by using those technologies. On the other hand, telemedicine is the use of communication technologies to provide medical care and thus avoid the usual face-to-face, physician-to-patient scenario. With telemedicine, a physician can treat a patient located at a remote site. Early telemedicine systems used technologies that were available at the time, such as the telephone. Integrating wireless technologies into telemedicine systems would surely provide a huge boost to the improvement of the delivery of healthcare. However, telemedicine and wireless technologies are both emerging scientific concepts. Scientific concepts always have to face challenges prior to popularisation. The more important barriers to the adoption of wireless telemedicine are security and privacy. Medical practitioners are doing their best to preserve the privacy of their patients. Disclosure of patients’ health information may lead to severe legal sanctions. Security flaws in a wireless telemedicine system would lead to privacy breaches. Patient privacy, which physicians have tried so hard to protect, would consequently be out of their control. This dissertation will achieve two goals. The first goal is to show how different wireless technologies could be integrated into telemedicine to provide different applications. The second goal is to design a fully wireless telemedicine system where the information of patients will flow securely. The model described in this dissertation shows a possible wireless telemedicine scenario using different types of wireless technologies. The model also proposes a solution to allow the secure flow of medical information in order to protect the privacy of patients. / Dr. E. Marais

The increasing competition between telecommunication service providers (TSPs) and the large amounts of human resource costs incurred to provision telecommunication services to small, medium and micro enterprises (SMMEs), highlight the need for effective self-service provisioning methods to reduce costs. Existing service provisioning methods do not effectively support SMMEs in the service provisioning process. The current methods used are manual and Web-based. The manual service provisioning method is labour and time-intensive. TSPs are being forced to cut human resource costs as the profit margins for provisioning services are narrow due to competition. The current web-based systems do not allow SMMEs to effectively purchase services as they provide long textual lists to consult and limited information about services. The objective of this research was to develop an intelligent web-based self-service system to support SMMEs in telecommunication service provisioning, using a Design Science Research methodology. A constraint-based, knowledge-based recommender system was selected as the most appropriate intelligent system to support telecommunication service provisioning. A prototype called SelPro was developed as a solution to address the shortcomings of the current ineffective service provisioning methods available for SMMEs. SelPro incorporates an interactive wizard-style user interface with dynamic recommendations to support novice users as well as an expert interface which provides less user support. An expert review and a user study were conducted to determine if SelPro was usable, useful and effective. SelPro was perceived as being usable for SMMEs wishing to purchase telecommunication services. Expert participants were satisfied with the usability of SelPro and perceived it as being useful, easy to use and easy to learn. SelPro was considered effective because of the high task success ratings provided by the participants using the two interfaces. The research determined that intelligent web-based self-service provisioning can be used to effectively support SMMEs in telecommunication service provisioning. General design recommendations for similar systems were proposed and future work will involve using intelligent systems to support large enterprises in telecommunication service provisioning.

M.Phil. / The advantages offered by power line communications (hereon after called PLC) cannot be over-emphasized neither can the inherent problems affecting its commercial takeover be underestimated. This research work creates a background study for experimental measurement and eventual implementations on power lines. It explains those salient aspects of commercially available communication modules that are rather not straight forward to understand from reading the Comblocks user manual. Especially, addressing those shortcomings of Comblocks that were not indicated in the documentation, we o er solutions to those we could nd our way around. M-ary frequency shift keying was implemented. This implementation tested the ro- bustness of the scheme against noises, attenuation and other power line channel char- acteristics as encountered practically. Based on our results, we nally recommend an optimal set of frequencies; we believe to be good for use in most PLC application pur- poses. Pseudo random bits of information were generated, encoded and modulated; the signals were transmitted over power line channels. The impact of noise sources, impulse noise especially was observed at di erent distances along the channel. Coupling and decoupling circuits used for this research, with associated issues sur- rounding the use of coupling circuitry are also presented. The CENELEC norm for PLC communication was adhered to, hence only frequencies that fall within the CENELEC speci cation for low voltage power distribution network were considered for MFSK use. Signal-to-noise ratio and other factors that a ect signal transmission over PLC was also measured. A complete communication system comprises of the transmitter, the channel and the receiver. This work however did not cover the receiver part of the system. Future work can now be done on this aspect which amongst others can take care of synchronization issues, in which a coding system as well as bit error rates can be determined.

M.Tech. (Computer Science) / The Signal Distribution department of the SABC does planning regarding the signal distribution or broadcasting network of the SABC. In order to do effective planning a tool had to be developed to assist in the planning of the broadcasting network. The Rand Afrikaans University was asked to supply a student to analyze the problems surrounding the development of such a tool and supply the SABC with a solution to the problems. The problems surrounding the development of a broadcast network planning model were the availability and accuracy of the information needed for planning. The data needed was spread throughout the country with only manual means to transport the data. The solution to the problem would be to develop a system to cope with the decentralized database and to gather the data in order to supply valuable planning information. To provide a framework for the solution of the planning problem, a broadcasting network was compared with a computer network. The comparison revealed a number of parallels between a broadcasting and a computer network. As a result of the resemblance between the two types of networks, a foundation for the development of a planning model for a broadcasting network could be identified. The ISO IS OSI approach was used as a foundation for the development of the model. The principles of the seven layers along with the three network management models The broadcasting network model was developed using the principles of the OSI approach, object orientation, geographical information systems and graphical user interfaces. A "package" was defined to assist in the logical data flow of the model. The package contains the specific data used in a calculation. A package containing information can be split or combined according to strict rules. The effective management of the package is a central issue in the development of the planning model. A prototype system was developed on PC-Arc/Info, a PC based GIS. The prototype's aim was to prove that the principles used in the model could be implemented successfully. As the developed system was intended to serve as a prototype, it did not implement the full functionality of the model, but only the functions necessary to prove the viability of the model.