Thesis (M.Ed.(Curriculum Studies))--University of Pretoria, 2006. / Summary in English. Includes bibliographical references. Available on the Internet via the World Wide Web.

Thesis (M.S. in Joint Campaign Planning and Strategy)--Joint Forces Staff College, Joint Advanced Warfighting School, 2007. / Title from title screen; viewed on July 9, 2007. "17 May 07." Electronic version of original print document. Includes bibliographical references (p. 78-83).

Thesis (M.S.)--University of North Carolina at Greensboro, 2007. / Title from PDF title page screen. Advisor: Shan Suthaharan; submitted to the Dept. of Mathematics and Statistics. Includes bibliographical references (p. 45-46).

Trellis coded modulation (TCM) schemes, due to their bandwidth efficiency and coding gain, have been proposed for multipath fading (MF) channels. The object of this research is to analyze the performance of TCM schemes in MF channels. While many excellent studies have already been reported, they share some of the following restrictions: (1) an assumption of ideal channel measurements and ideal interleaving, (2) use of Chernoff bounds, which are loose in this case, (3) analysis of only the Rayleigh channel, ignoring the Rician channel, and (4) reliance on computer simulation to get the actual performance. Extending analytical results without these restrictions is addressed in this work. This thesis derives a saddle point approximation (SAP) method to compute the pairwise error probability (PEP) of TCM schemes transmitted over Rician fading channels. It can be applied under several conditions, including finite or ideal interleaving, and is derived for a pilot-tone model, encompassing ideal coherent detection, pilot-tone aided detection, pilot-symbol aided detection, and differential detection. Its accuracy is demonstrated by comparison to the results of numerical integration. Under ideal interleaving, the approximation can be further simplified to an expression, which is in a product form and is much tighter than the ordinary Chernoff bound on the PEP. Also, based on the SAP, the effect of finite interleaving depth on the error performance is studied. The Canadian mobile satellite (MSAT) channel has been modelled as the sum of lognormal and Rayleigh components. Previously, the performance of TCM schemes in this channel has been obtained via computer simulation. In this thesis, new analytical expressions are derived for the PEP of TCM schemes transmitted over this channel employing ideal interleaving, and the results are substantiated by means of computer simulation. In addition, first order statistics of absolute and differential phases of a shadowed Rician process are derived. This thesis presents new performance bounds of TCM schemes over nonindependent (i.e., finite interleaving) Rician fading channels. In addition, for Rayleigh fading channels with an exponential auto-covariance function, bounds resembling those for memoryless channels are derived. The bounds, being more accurate than Chernoff bounds, permit accurate estimation of system performance. The performance of concatenated coding systems and automatic-repeal-request (ARQ) systems operating on fading channels is addressed. New error expressions,which sow asymptotic error behaviour, are derived for systems which use a modified Viterbi decoding algorithm. They allow useful evaluation of the coding gain and throughput. Finally, the performance of convolutional codes in fading channels is analyzed. An upper bound on the bit error probability, the optimum power split ratio between the data and pilot signals, and the channel cut-off rate are derived. / Graduate

Thesis (M.Diploma in Technology)--Cape Technikon, 1993 / This thesis describes the development of a 5-Tone Zentral Verband Electrotechische Industrie eZVEI) Encoder Analyser. The 5-Tone ZVEI Encoder Analyser is used by the Radio Section of the Test and Metering Branch, which falls under the Electricity Department of the Cape Town City Council. It assists the Quality Assurance Technician in determining whether the 5 tone ZVEI encoder, of the radio under test, is operating within the manufacturers specifications. Various manufacturers of radio equipment tender for the supply of mobile radios fitted with ZVEI tone The Radio Section are now capable of testing encoders. all the various radios and comparing the analysed ZVEI specifications of each manufacturer's radio. The results can be used to assist management in deciding which radio would be the most suitable for purchasing. The development of the 5-Tone ZVEI Encoder Analyser involved the design and development of hardware and software. It was designed to be housed in a compact enclosure and to interface to a Motorola Communications System Analyser Model R-2001C. The RF output, from the radio under test, connects to the RF input of the Communications System Analyser. The demodulated output of the Communications System Analyser connects to the input of the 5-Tone ZVEI Encoder Analyser. The softwa~e was designed using PLM-51 high level language to p~ovide ~eal-time analysis of va~ious selective-calls (selcalls) ~eceived f~om the demodulated output of the Communications System Analyser. Once all 5 tones of the ZVEI selcall have been analysed the software background task is flagged and the analysed results a~e displayed as various MODES of display on a 16 cha~acte~ by 4 line dot matrix display. The following parameters of the ZVEI selcall a~e analysed: i) Frequency Digits. ii) Frequency fo~ each of the 5 tones. iii) Tone Duration for each of the 5 tones. iv) Frequency Error for the 5 tones. v) Tone Duration Er~or for the 5 tones. The design and development of the 5-Tone ZVEI Encode~ Analyser was conducted at the Computer Section of the Electricity Depa~tment, Cape Town City Council.

Usability is seen as an important aspect for the quality of an M-learning application. Yet very little research has been conducted in this area – particularly in South Africa. Even though the trials of M-learning projects have been witnessed in the country during the last five years, very little is known about the systems that were implemented as regards their usability. Additionally, metrics and measures used in evaluating usability have not been reported. A need exists for relevant metrics to M-learning usability. The primary objective of this work was to propose metrics and measures – for the purpose of evaluating the User-Interfacedesign usability of M-learning application. The research included a literature review of M-learning, as well as the development of metrics and measures based on the Goal Question Metric (GQM) Model. This model has helped provide a reference model and measurements for evaluating the User-InterfaceUsability. A case study was used as a research strategy. An application called Kontax was selected for evaluation by users and expert reviewers. Data-collection methods consisted of User Testing and Heuristics evaluations. Data-gathering instruments included the use of surveys and user- satisfaction questionnaires based on the proposed metrics, task scenarios and expert-reviewed questionnaires based on the proposed metrics; all these instruments were developed. It was found that, although the users thought the system was very interesting, and they wished to hear more about it in the future, the system nevertheless had usability flaws which made it difficult to use. All the users failed to register so that they could use the system; additionally, the system-error messages did not help the users recognize, and recover from an error – leaving the user to simply log out. Help was not adequate, thus making it difficult for first-time users to know what to do when they needed support. The system was also said to have a lot of information presented on its home page, which caused the user to be disoriented. The Kontax application has usability flaws which should be III attended to, in order to improve its usability. The proposed metrics proved to be very useful in evaluating the usability of the tool.

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

University of Macau / Faculty of Science and Technology / Department of Computer and Information Science

Wireless communications have recently gained much popularity in various commercial applications. Because of the peculiar characteristic of radio channels, the ability for communicators to stand various kinds of interference in the open air is one of the most important issues in wireless communications. The focus of this dissertation is on the analysis and cancellation of narrowband interference (NBI) which is one very detrimental form of interference. To facilitate the analysis of SFH/DPSK under tone interfere, an analytical framework is developed for determination of the probability distribution of a corrupted differential phase. The concept of the phase characteristic function is introduced and its characterizations such as factorization are investigated. Based on it, expressions are derived for the general probability distribution of a received differential phase corrupted by signal tone interference and Gaussian noise under non-fading as well as different fading environments. Furthermore, we also derive the probability distribution of a received differential phase perturbed by multiple tone interference. Subsequently, an extensive analysis of SFH/DPSK is carried out in terms of bit error rate performance given different signalling schemes, fading environments and jamming strategies using band multitone and frequency jitter. Finally, we propose a new technique for rejection of narrowband interference based on multiple symbol detection of coherent or differential phase shift keying. We first show that the direct use of multiple symbol detection offers poor performance when narrowband interference is dominant. Our proposed technique employs a special signalling or coding scheme which is shown to be robust against narrowband interference. Our evaluation of bit error rate shows significant performance improvement in narrowband interference vis-a-vis direct multiple symbol detection. When viewed as a coding scheme, the proposed signalling scheme is significantly simpler for achieving the same coding gain than conventional error correction codes. / Graduate

The features and capacities of mobile devices offer a wide range of significant opportunities for providing learning content in workplaces and educational institutions. This new approach of teaching, called mobile learning, allows for the delivery of learning content on the move at any time. Mobile learning supports learning by producing learning content to learners in a modern and acceptable way. The number of mobile learning applications has increased rapidly in educational environments. There are, however, limited mobile learning applications that take advantage of mobile devices to support contact learning in the classroom environment. The aim of this research was to design a mobile learning architecture to effectively support contact learning in the classroom. The researcher investigated the historical and theoretical background of mobile learning and reported these findings. This included an overview of existing mobile learning architectures. After identifying their limitations, the researcher designed the Contact Instruction Mobile Learning Architecture (CIMLA) to facilitate the use of mobile devices in the classroom. The researcher developed the LiveLearning prototype based on the proposed architecture as a proof of concept. He conducted a usability evaluation in order to determine the usability of LiveLearning. The results indicated that the LiveLearning prototype is effective in supporting contact learning in the classroom.