D. Tech. (Department of Process Control and Computer Systems, Faculty of Engineering and Technology), Vaal University of Technology. / In this research study, a scheme to minimise interference in converged mobile cellular networks (MCNs) and wireless sensor networks (WSNs) was designed and implemented. The focus was the mitigation of interference that arises when proximity service (ProSe)-enabled sensors engage in a device-to device (D2D) communication to alert smartphone users upon the detection of explosives at highly crowded areas like shopping malls. D2D is a technology that academia and industry experts believe will play a prominent role in the implementation of the next generation of mobile networks, specifically, the fifth generation (5G). However, the full roll out of D2D is being impeded by the interference that the technology introduces to the cellular network. D2D devices cause a significant amount of interference to the primary cellular network especially when radio resources are shared. In the downlink phase, primary user equipment is likely to suffer from interference emanating from a D2D transmitter. On the other hand, the immobile base station is affected by interference caused by the D2D transmitter in the uplink phase. This type of interference can be avoided or reduced if radio resources are allocated intelligently under strict coordination of the base station. An NP-hard optimisation problem was formulated and finding a solution to this problem in 1 ms is not possible. 5G has a frame structure duration of 10 ms with 10 subframes of 1 ms each. Heuristic algorithms were then developed to mitigate the interference affecting the primary network that could carry out resource allocation within the fast-scheduling period of 1 ms. Smartphones have progressed into devices capable of generating massive volumes of data. The challenge is that battery technology is not keeping up with the pace of smartphone technology, so any additional feature that designers want to add, is met with a lot of contempt from customers who are concerned about their smartphone batteries depleting rapidly. In this context, the strategy must be energy-efficient for smartphone users to embrace it. A system level simulator was developed using MATLAB to evaluate the efficacy of the proposed design. Extensive simulation results showed that ProSe-enabled sensors can safely be integrated into cellular networks participating in D2D communication with smart phones, without introducing significant harm to the primary cellular network. The results showed that after implementing the proposed strategy, overall user throughput decreased by 3.63 %. In cellular networks, this is a modest figure since a reduction of up to 5% is acceptable to both users and network providers. The figure generally capped in service level agreements signed between network providers and users is 5%. The proposed technique also resulted in a 0 % reduction in SINR of CUEs in a cellular network, according to the findings. In terms of D2D link throughput for different D2D transmit levels, the method proposed in this research work surpassed a similar scheme proposed in literature by an average of 18.3%.

[pt] ContextNet é um middleware de comunicação baseado no padrão OMG DDS, que suporta monitoramento em tempo real, unicast, groupcast e transmissão para milhares de nós móveis. Este trabalho substituiu a infraestrutura DDS (Data Distribution Service), utilizada na comunicação dos nós Core da ContextNet, pela plataforma Kafka; simplificou a construção de aplicativos que utilizam o middleware ContextNet; e adicionou novos recursos. Kafka é uma plataforma de streaming capaz de subscrever, publicar, armazenar e processar em fluxos em tempo real. A utilização do Kafka permitiu que as aplicações construídas sobre o ContextNet sejam paralelizáveis. / [en] ContextNet is a communication middleware based on the OMG DDS standard that supports real-time monitoring, unicast, groupcast, and broadcast to thousands of mobile nodes. This work replaced the DDS (Data Distribution Service) infrastructure used to communicate the ContextNet Core nodes with the Kafka platform; simplified the construction of applications that use the ContextNet middleware; and added new features. Kafka is a streaming platform capable of subscribing, publishing, storing, and processing in realtime streams. Using Kafka has enabled applications built on top of ContextNet to be parallelizable.

A large proportion of the farming in Kenya and Eastern Africa is performed by smallholding farmers. At the same time, consumers are expecting to find foodstuff more close by and in a more convenient way than most smallholding farmers can provide. Crowdsourcing can efficiently be applied to many problems where many small producers need to collaborate to create the complete product, without exposing much of the complex process to the end consumers. Using semi structured interviews, systematic literature review and prototyping, the application of crowdsourcing to reach and empower smallholding farmers was explored. The findings were used to create recommendations in the form of guidelines that are expected to serve as ground work and background to future studies within the area. In general, a mobile based platform for crowdsourcing was found to be viable while still having some problems with the intended target market. Three primary factors which affects the potential success were identified; The generally low availability of internet to smallholding farmers (limited by high prices), lacking education which can limit comprehension of more complicated processes, and smartphones with limited capacity for advanced applications. / En stor del av jordbruket i Kenya och östra Afrika utförs av småbönder. Samtidigt förväntar sig konsumenter att kunna hitta matprodukter närmare och på ett mer bekvämt sätt än de flesta småbönder kan erbjuda. Crowdsourcing kan effektivt tillämpas på många problem där flera små producenter behöver samarbeta för att skapa den kompletta produkten utan att utsätta slutkonsumenten för den komplexa processen. Med hjälp av semi-trukturerade intervjuer, systematisk litteratur studie och prototyping, undersöktes tillämpningen av crowdsourcing för att nå och förstärka småbönder. Resultaten användes för att skapa rekommendationer i form av riktlinjer som förväntas fungera som grundarbete och bakgrund till framtida studier inom området. I allmänhet visade sig en mobilbaserad plattform för crowdsourcing vara realistisk, samtidigt som den fortfarande hade några problem med den avsedda målmarknaden. Tre primära faktorer som påverkar den potentiella framgången identifierades. Dessa var den generellt låga tillgängligheten av internet till småbönder (begränsad av höga priser), avsaknad av utbildning som kan begränsa förståelsen av mer komplicerade processer, och smartphones med begränsad kapacitet för avancerade applikationer.

M. Tech. (Department of Marketing Management, Faculty of Management Sciences), Vaal University of Technology. / The evolution of social media has seen people around the world connect with one another, communicate and share information without boundaries and time limitation. Social media is no myth, neither is it just a trend but a powerful communication medium which presents a fundamental shift in communication that cuts across all cultures, be it social, business, politics, sports, news and more. Social media adoption over the years, has seen billions of people participating on social networking sites and the interaction thereof has considerably influenced marketing related correspondence, public relations as well as modern day business communication. In the connected world, social media interaction is the current word-of-mouth, often referred to as electronic word of mouth and in the connected world, everyone is a content generator. In this social media era, information travels faster, reaching millions of consumers and affecting their perception towards certain products and brands based on the information shared and received. Therefore, social media interaction has proved to be an important contributing factor in consumer’s purchase decision process. However, this evolution in communication introduces unprecedented challenges as well as opportunities for organisations as buying decisions are affected significantly by social media interaction, and thus warranties a study of this nature to be carried out. The aim of this study was to examine the influence of social media on brand awareness as well as the relationships between brand awareness, perceived quality, brand loyalty and purchase intention. To attain the empirical objectives of the study, a quantitative research design was adopted and the respondents were selected using a non-probability convenience sampling technique. For data collection, the researcher used a structured self-administered questionnaire survey. Of the 320 distributed questionnaires, the researcher utilised 304 usable questionnaires for data analysis. The Statistical Package for Social Sciences (SPSS) version 25.0 was used to compute both descriptive and inferential statistics (which includes correlation and regression analysis). In addition, the reliability and validity analysis were carried out in relation to the measuring instrument. Results from the correlation and regression analysis revealed positive significant relationship between social media and brand awareness, brand awareness and perceived quality, brand loyalty and purchase intention, perceived quality with brand loyalty and purchase intention as well as brand loyalty and purchase intention. Based on the results of the study, recommendations emanating from the study include the integration of social media marketing in the organisation’s overall marketing strategy, creating and maintaining online brand communities to engage with current and potential customers as well as making use of social media platforms for advertising and promotions. The limitations of the study and the proposed opportunities for further research were also highlighted.

M. Tech. (Department of Information Communication Technology, Faculty of Applied and Computer Sciences), Vaal University of Technology. / The influence of Information and Communication Technology (ICT) in the education system has encouraged both students and educators to become more and more computer literate. With the increased use of portable devices (tablets, PDAs, Smartphones, iPads etc.), mobile learning (m-learning) has gained popularity as it is believed to be an effective and efficient tool for content presentation and knowledge acquisition in education sector. The realisation of the benefits depends on the effective adoption of m-learning technology. The superseding purpose of this study was to investigate the adoption of mobile learning at a University of Technology (UoT) in South Africa. A quantitative study was carried out at an UoT in South Africa, with respect to mobile learning perceptions; 64 valid questionnaires were received from the participants. The proposed research framework/model derived from Extended Technology Acceptance Model (ETAM) and Technology Acceptance Model 3 (TAM3) was used. The Statistical Package for the Social Sciences (SPSS), version 25.0. was used for analysing data. The findings revealed that perceived usefulness of mobile learning, attitude toward mobile learning, service and system quality as well as perceived ease of use are significant predictors of intention to use mobile learning application. Perceived mobility on mobile learning strongly influences perceived usefulness more than perceived ease of use of mobile learning application. The study concluded that it is necessary to measure perception of potential users using the variables in the model proposed before adoption of mobile learning application to ascertain an effective adoption of the technology in education.

The objectives of this research work are to investigate, design and implement circularly-polarized antennas to be used for handheld satellite mobile communication and wireless sensor networks. Several antennas such as Quadrifilar Spiral Antennas (QSAs), two arm Square Spiral and stripline or coaxially-fed microstrip patch antennas are developed and tested. These antennas are investigated and discussed to operate at L band (1.61-1.6214GHz) and ISM band (2.4835-2.5GHz) A substantial size reduction was achieved compared to conventional designs by introducing special modifications to the antenna geometries. Most of the antennas are designed to produce circularly-polarized broadside-beam except for wireless sensor network application a circularly-polarized conical-beam is considered. The polarization purity and Specific Absorption Rate (SAR) of two dual-band antennas for satellite-mobile handsets next to the human head are investigated and discussed, using a hybrid computational method. A small distance between the head and the handset is chosen to highlight the effects of the relatively high-radiated power proposed from this particular antenna. A Genetic Algorithm in cooperation with an electromagnetic simulator has been introduced to provide fast, accurate and reliable solutions for antenna design structures. Circularly-polarized quadrifilar helical antenna handset and two air-dielectric microstrip antennas were studied. The capabilities of GA are shown as an efficient optimisation tool for selecting globally optimal parameters to be used in simulations with an electromagnetic antenna design code, seeking convergence to designated specifications. The results in terms of the antenna size and radiation performance are addressed, and compared to measurements and previously published data.

This dissertation focuses on quantifying the effects of multi-user co-channel interference for an avionic communication system operating in a heavy-traffic aeronautical mobile environment and proposes advanced interference cancellation techniques to mitigate the interference. The dissertation consists of two parts. The first part of the work investigates the use of a visualization method to quantify and characterize the multi-user co-channel interference (multiple access interference) effects impinging on an avionic communication system. The interference is caused by complex interactions of thousands of RF signals transmitted from thousands of aircraft; each attempts to access a common communication channel, which is governed by a specific channel contention access protocol. The visualization method transforms the co-channel interference, which is specified in terms of signal-overlaps (signal collisions), from a visual representation to a matrix representation for further statistical analysis. It is found that the statistical Poisson and its cumulative distribution provide the best estimates of multi-user co-channel interference. It is shown, using Monte Carlo simulation, that the co-channel interference of a victim aircraft operating in the heavy-traffic environment could result in as high as eight signal-overlaps. This constitutes to approximately 83.4% of success rate in signal detection for the entire three thousand aircraft environment using conventional FSK receiver. One key finding shows that high-quality communications, up to 98.5% success rate, is achievable if only three overlapping signals can be decoded successfully. The interference results found in the first part set the stage for interference cancellation research in the second part. The second part of the work proposes the use of advanced interference cancellation techniques, namely sequential interference cancellation (SIC) and parallel interference cancellation (PIC), as potential solutions to mitigating the interference effects. These techniques can be implemented in radio receivers to perform multi-signal decoding functionality to remove the required interferers (three overlapping signals) so that high-quality communication, as described in the first part, can be achieved. Various performance graphs are shown for B-FSK and B-PSK for both SIC and PIC techniques. One key finding is that the system performance can be improved substantially to an additional 15% in signal reception success rate by using SIC or PIC. This means that critical information transmitted from 450 aircraft (out of approximately three thousand aircraft in the environment) is preserved and successfully decoded. Multi-signal decoding using these interference cancellation receivers comes at a small penalty of 2 - 4.5 dBs in Eb/No when sufficient signal-to-interference (SIR) ratio (7-12 dB) is provided. / Ph. D.

The increasing demand for greater capacity of mobile communications has led to the petition of more radio spectrum at 1900 MHz for the new personal communication service (PCS) systems. The PCS spectrum is proposed to coexist with current fixed microwave spectrum. This presents cochannel interference control problems which can be avoided with extensive propagation studies in both measurements and predictions. Currently, there is no readily available tool to predict propagation channels for the small coverage area that PCS operates at 1900 MHz. This thesis presents new methods for propagation prediction without relying on measurements but rather local environment geometries and their electrical properties. The propagation prediction tool developed is based on the principle of geometrical optics and Fresnel-Kirchoff diffraction. Geometrical optics enables computer software to automatically trace the propagation of radio wave energy from the transmitter to the receiver. The ray tracing techniques presented are optimized for speed with a little trade-off in accuracy. Also, efficient techniques were developed to find true diffracting building edges in dense urban environments. The propagation prediction software also rely on other commercial software packages such as AutoCAD and GRASS to maintain and manipulate the environmental database as well as displaying prediction results. The software yielded reasonable accuracy when compared against VT campus propagation measurements at 900 MHz and 1900 MHz. / Master of Science

Personal handheld mobile technology represents a growing topic of interest for K-12 educators. Devices such as iPads, tablets, and smartphones, in particular, are becoming more ubiquitous in society and prevalent in classrooms of children of all ages. The ease of access, combined with growing functionality and capacity of these devices creates opportunities that were previously unimaginable. Professional educators are beginning to recognize the value such devices offer for enriching and expanding opportunities for learning both inside and outside of the classroom. The views of educators and students regarding mobile technology have been well documented in existing literature. What is less clear is how parents view personal mobile technology when applied to formal and informal learning opportunities. Using quantitative analysis, this study examines the views of parents when mobile technology is utilized in Singaporean third grade classrooms. This study represents a pioneering effort to better understand the evolving role of parents and serves as a foundation for future research to explore the role of parents as partners when personal mobile technology is used for learning. The constructs identified in this study reveal that parents do believe technology skills are important in the modern age of learning and working.

The architecture of mobile networks has dramatically evolved in order to fulfill the growing demands on wireless services and data. The radio resources, which are used by the current mobile networks, are limited while the users demands are substantially increasing. In the future, tremendous Internet applications are expected to be served by mobile networks. Therefore, increasing the capacity of mobile networks has become a vital issue. Heterogeneous networks (HetNets) have been considered as a promising paradigm for future mobile networks. Accordingly, the concept of small cell has been introduced in order to increase the capacity of the mobile networks. A femtocell network is a kind of small cell networks. Femtocells are deployed within macrocells coverage. Femtocells cover small areas and operate with low transmission power while providing high capacity. Also, UEs can be offloaded from macrocells to femtocells. Thus, the capacity can be increased. However, this will introduce different technical challenges. The interference has become one of the key challenges for deploying femtocells within a certain macrocells coverage. Undesirable impact of the interference can degrade the performance of the mobile networks. Therefore, radio resource management mechanisms are needed in order to address key challenges of deploying femtocells. The objective of this work is to introduce radio resource control approaches, which are used to increase mobile networks' capacity and alleviate undesirable impact of the interference. In addition, proposed radio resource control approaches ensure the coexistence between macrocell and femtocells based on LTE-Advanced environment. Firstly, a novel mechanism is proposed in order to address the interference challenge. The proposed approach mitigates the impact of interference based on controlling radio sub-channels' assignment and dynamically adjusting the transmission power. Secondly, a dynamic strategy is proposed for the FFR mechanism. In the FFR mechanism, the whole spectrum is divided into four fixed sub-channels and each sub-channel is assigned for a different sub-area after splitting the macrocell coverage area into four sub-areas. The objective of the proposed scheme is to divide the spectrum dynamically based on the QoS indicators for each sub-area. Lastly, a novel packet scheduling scheme is proposed to improve the performance of femtocell networks. The proposed scheduling strategy assigns radio resources based on two objectives: increasing the network capacity and achieving better fairness among attached UEs.