3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item A software architecture for a real-time big data system: a case study of a spectrum-sensing enabled whitespace database(2018) Montsi, Litsietsi GeorgeDue to the ever-growing need to process vast amounts of data in real-time, more and more tools which serve different needs in the real-time Big Data processing pipeline have sprung out. However, holistic industry accepted frameworks that address all real-time Big Data processing requirements across the entire pipeline have not yet been developed. More so, the area of dynamic spectrum access, has more and more devices connecting to previously unavailable radio frequency spectrum. This vastly growing number of devices need real-time orchestration on how they access this newly made available spectrum. The development of a real-time Big Data system in the realm of dynamic spectrum access as required by the Council for Scientific and Industrial Research served as a case study for this research. This research provides a step in reaching an industry wide accepted software reference architecture which will be followed in the development of real-time Big Data systems. This is done through uncovering the most important quality/architectural requirements of realtime Big Data systems which such a reference architecture is to address. It is shown that all major software reference architectures (Java Enterprise Edition, AutoSar, Microsoft.Net, and others) were developed with emphasis placed on addressing a set of specific prioritised requirements. Hence this research uses this principle to propose a method to help in the development of software architectures and software reference architectures of real-time Big Data systems. In this research, a case study is used to make inference on the general population of real time Big Data systems about the method proposed in this research. A mathematical ranking method is employed to prioritise software architecture requirements of a case study system and the results are compared with literature to increase the accuracy of the inference. Then architecture design and experiments were carried-out and presented to the Council for Scientific and Industrial Research as the client for acceptance, which would serve as validation. This was further validated by comparing the results of the case study to work done by other researchers. Having uncovered the most important quality attributes for realtime Big Data systems, the software architecture design process for such systems is simplified and fertile ground has been laid for the development of software reference architectures for real-time Big Data systems.Item Raw material selection for object construction(2018) Perlow, JasonAgents, such as assembly robots, are typically incapable of building objects without a predefined goal or predefined set of materials. Extending the construction capabilities of agents to objects and materials that an agent has not seen before would therefore greatly improve the scope of objects that agents can construct. An important step in building novel objects is the ability to recognise combinations of raw materials which are likely to be useful. As a step toward automating this step, we aim to exploit the intuition that the visual characteristics of candidate raw materials provide useful cues to their potential combinations. Toward this end, we present a Siamese neural network based model that is able to recognise unseen raw materials present in objects given a list of candidate material images. We demonstrate the utility and efficacy of our model within two domains. The first is a single material selection domain that uses the ShapeNet 3D model dataset where we attempt to recover the materials present in a model. The second is a multiple material domain using the adventure game Minecraftwherewepredictthecombinationsofmaterialsthatwillresultinatargettool. Weempirically demonstrate that by recognising the visual similarities between objects and materials our model is able to learn from a subset of object material pairs and generalise to unseen objects, materials and texture packs. We perform such tests by showing that our model outperforms chance and baseline methods.Item The effects of Botswana's policy and regulatory frameworks on competion in the provision of broadband internet(2017) Pelaelo, Kenaope PhetogoA country’s policy and regulatory frameworks can be favourable or detrimental to competition amongst operators and service providers in a given market. This report presents the outcomes of an investigation conducted on Botswana’s broadband policy and regulatory frameworks, to determine their effects on competition in the provision of services. The study examined market liberalisation; open access to infrastructure networks; and initiatives for universal access to broadband Internet, exploring several components under each intervention. It reached the overall conclusion that policy and regulation in Botswana have enabled significant service-based competition in the broadband market, while remaining less favourable to facility-based competition. The study briefly explored the framework on open access to infrastructure networks in relation to the ladder of investment (LoI) theory, which is a theoretical underpinning of competition in telecommunications markets. It concluded that the framework does not take heed of the LoI theory, more so that its key assumption that infrastructure investment can be stimulated through systematic price regulation of facilities, such as local loop unbundling and Mobile Virtual Network Operator (MVNOs) access to networks owned by other operators, have not been applicable in Botswana. This is mainly because local loop unbundling and authorisation of MVNOs have never been implemented in the country. While the study calls for improvements to encourage facility-based competition as the most ideal form that is considered to have higher efficiency, it makes an argument for factors that may have constrained the country and made service-based competition a preferred route for most of the service providers. Qualitative research techniques have been employed, using semistructured interviews and document analysis to explore the focus area. Acknowledging that other factors such as population size and distribution; cost of infrastructure deployment; and choice of business models may have contributed to the key research conclusion, the study draws recommendations for the consideration of policy makers, the regulator and service providers. Keywords: Broadband Internet, policy, regulation, infrastructure, services, investment, service-based competition, facility-based competition, Botswana.Item Investigating motivational factors influencing broadband adoption and usage in South African low-income households(2018) Monyetsane, KopanoBroadband technology has been identified as a vital contributor to socio-economic development in South Africa. Hoverer, the rate of broadband adoption and usage in low-income households is lower as compared to middle and high-income households. Although there are studies that have presented motivational factors for broadband adoption in South Africa, there is little knowledge about how these motivational factors collectively influence the adoption and usage of broadband in low-income households and how they use the technology. To address this gap, this study investigated motivational factors that influence low-income households in South Africa to adopt and use broadband. An extended Model for Broadband Adoption (MBA) was derived from literature and used to provide the basis for the theoretical and conceptual framework for this study. The researcher then followed a phenomenological approach to collect qualitative data that was analysed using a computer-assisted qualitative data analysis software (CAQDAS). The findings of this study show that the participants from low-income households used broadband everyday but only for basic applications and the high cost of data hindered increased usage. The findings further suggest that attitude, normative beliefs and control factors can have both positive and negative influence on the adoption and usage of broadband by low-income households. In addition, low-income households regarded broadband as a key element towards improving their livelihood and confirmed the lack of local content in most broadband platforms. The study recommends that policy makers, regulatory authorities and broadband service providers should consider adopting models such as the MBA to advance their understanding on the interactions between low-income households and broadband, in order to develop policy interventions and products that are relevant to the lived experience of low-income households. The study emphases further the importance of expediting policies and regulations that are meant to address the high cost of data to ensure that broadband adoption and usage is inclusive of all income groups in South Africa.Item An investigation into jamming GSM systems through exploiting weaknesses in the control channel forward error correction scheme(2017) Timm, GarethThe ability to communicate effectively is of key importance in military scenarios. The ability to interfere with these communications is a useful tool in gaining competitive advantages by disrupting enemy communications and protecting allied troops against threats such as remotely detonated explosives. By reducing the number of corrupt bits required by using customised error patterns, the transmission time required by a jammer can be reduced without sacrificing effectiveness. To this end a MATLAB simulation of the GSM control channel forward error correction scheme is tested against four jamming methodologies and three bit corruption techniques. These methodologies are aimed at minimising the number of transmitted jamming bits required from a jammer to prevent communications on the channel. By using custom error patterns it is possible to target individual components of the forward error correction scheme and bypass others. A ran dom error approach is implemented to test the system against random errors on the channel, a burst error approach is implemented to test the convolutional code against burst errors, and two proposed custom error patterns are implemented aimed at exploiting the Fire code’s error detection method. The burst error pattern approach required the least number of transmitted jamming bits. The system also shows improvements over current control channel jamming techniques in literature.Item Controller-plane workload characterization and forecasting in software-defined networking(2017) Nkosi, EmmanuelSoftware-defined networking (SDN) is the physical separation of the control and data planes in networking devices. A logically centralised controller plane which uses a network-wide view data structure to control several data plane devices is another defining attribute of SDN. The centralised controllers and the network-wide view data structure are difficult to scale as the network and the data it carries grow. Solutions which have been proposed to combat this challenge in SDN lack the use of the statistical properties of the workload or network traffic seen by SDN controllers. Hence, the objective of this research is twofold: Firstly, the statistical properties of the controller workload are investigated. Secondly, Autoregressive Integrated Moving Average Models (ARIMA) and Artificial Neural Network (ANN) models are investigated to establish the feasibility of forecasting the controller workload signal. Representations of the state of the controller plane in the network-wide view in the form of forecasts of the controller workload will enable control applications to detect dwindling controller resources and therefore alleviate controller congestion. On the other hand, realistic statistical traffic models of the controller workload variable are sought for the design and evaluation of SDN controllers. A data center network prototype is created by making use of an SDN network emulator called Mininet and an SDN controller called Onos. It was found that 1–2% of flows arrive within 10 s of each other and more than 80% have inter-arrival times in the range of 10 s–10ms. These inter-arrival times were found to follow a beta distribution, which is similar to findings made in Machine Type Communications (MTC). The use of ARIMA and ANN to forecast the controller workload established that it is feasible to forecast the workload seen by SDN controllers. The accuracy of these models was found to be comparable for continuously valued time series signals. The ANN model was found to be applicable even in discretely valued time series data.Item NRENs as ICT infrastructure to support e-Services at universities: a case of Wits University(2015) Sekgobela, EugueniaThe research report examined the value brought by NRENs, by investigating the utilization of the South African National Research Network (SANReN) at the University of the Witwatersrand (Wits). It explored the SANReN as the main international bandwidth service for the university and assessed how the university is able to efficiently provide a range of e-services in scientific research through the NREN. Wits scientists engaged in data intensive research and international research collaboration shared the view that the SANReN infrastructure is critical to such work, however due to infrastructure limitations at university level, it is sometimes difficult to maximize the value of this dedicated network, where data storage capacity is low. A wide range of e-services, such as grid computing, use SANReN, but are limited by international bandwidth. A further problem is the high cost of international bandwidth, particularly as the demand for bandwidth increases with the amount of data required in scientific research. The biggest challenge is the growth of demand and the ability to meet this demand. As scientific research relies on real time data, but experiences problems with data storage, advanced data infrastructure is needed in the form of a medium sized data centre, which would be used for storing and transferring large data sets and terabytes of data in and out of the country. In conclusion, although SANReN makes it possible for big science projects to take place at universities, it is somewhat difficult to measure the value that SANReN brings, due to the many limitations mentioned. Therefore a matrix to measure outputs and value of SANReN is required, as proposed in Chapter 6 of this research report.Item An SDN-based firewall shunt for data-intensive science applications(2016) Miteff, SimeonData-intensive research computing requires the capability to transfer les over long distances at high throughput. Stateful rewalls introduce su cient packet loss to prevent researchers from fully exploiting high bandwidth-delay network links [25]. To work around this challenge, the science DMZ design [19] trades o stateful packet ltering capability for loss-free forwarding via an ordinary Ethernet switch. We propose a novel extension to the science DMZ design, which uses an SDN-based rewall. This report introduces NFShunt, a rewall based on Linux's Net lter combined with OpenFlow switching. Implemented as an OpenFlow 1.0 controller coupled to Net lter's connection tracking, NFShunt allows the bypass-switching policy to be expressed as part of an iptables rewall rule-set. Our implementation is described in detail, and latency of the control-plane mechanism is reported. TCP throughput and packet loss is shown at various round-trip latencies, with comparisons to pure switching, as well as to a high-end Cisco rewall. Cost, as well as operations and maintenance aspects, are compared and analysed. The results support reported observations regarding rewall introduced packet-loss, and indicate that the SDN design of NFShunt is a technically viable and cost-e ective approach to enhancing a traditional rewall to meet the performance needs of data-intensive researchersItem Culture as a moderator for the infusion of Web 2.0 technology: TAM vs WebQual(2012-06-29) Hammerich, WestleyIt is clear that the internet is being used more often for social interactions but the reasons why people adopt these newer technologies are still unclear. Over the last thirty years numerous adoption theories have been proposed however few account for the newer types of technology, such as social website usage. Purpose – The study will compare and contrast two different models of adoption to see if one model is better than the other in understanding the usage of social networking websites such as Facebook. At an organisational level the idea of extended usage of technology has been encapsulated in the construct of infusion of technology into a work place. The study will also show that infusion of technology may occur at an individual level of research. The argument is made that since national culture has been shown to affect usage, national culture may moderate the level of infusion that is found. Methodology – The study will use a quantitative methodology to survey potential (or actual) users of Facebook using a structured questionnaire. Since two adoption models are being tested, two questionnaires were developed and tested. The items for the questionnaires have been adapted from prior literature. Reliability and validity tests confirmed the scales from prior literature. The sample was selected from higher education institutions within the Johannesburg region .Specifically, students from the University of the Witwatersrand and the University of Johannesburg were invited to complete the questionnaires. The two questionnaires were mixed randomly between the students. Findings – It was found that the traditional technology acceptance model could better explain the usage of social networking websites when compared to the more modern WebQual framework. The study found that there is a strong positive relationship between usage and infusion. In line with the prior research on national culture moderating usage, the study found that national culture does moderate the relationship between usage and infusion. Implications – The study has a number of implications. Firstly, the research compared two models of technology usage. The study showed that the technology acceptance model was better at explaining the usage of social networking websites. Future research should focus on improving the TAM model and may result in better understanding the usage of social websites. Secondly, a set of scales are provided for future research which allow for the measurement of infusion at an individual level. These scales were tested for reliability and validity in two separate data collections and in both collections the scales met or exceeded the statistical requirements. Thirdly, the relationship between usage and infusion is seen to be moderated by national culture. This has 5 large implications for organisations and people who use Web2.0 as a medium for business. As an example, marketers could use the results in better understanding the usage of these types of websites, in the hope that it would allow for better targeting and placement of adverts. Lastly, the implications may extend beyond the context of the research. The study found a relationship between usage and infusion at an individual level of analysis. The relationship may exist in other areas of research which relate to Information systems including but not limited to Marketing (increasing the life cycle of products and increasing the value of customers through brand loyalty) and human resources (increasing employee efficiency through understanding peoples infusion of different types of technology). Research limitations – The research is limited to the sample that was achieved. The findings can be directly inferred to a similar sample base within South Africa, however cannot be generalised to samples of dissimilar natures. While the study used Facebook as a case, it should be cautioned that the results should not be generalised to other forms of social networking websites such as Twitter. Originality – The study is original in the following ways: Firstly, the study was conducted in South Africa where few other studies been found with a similar nature. Secondly, the study extended the thoughts on usage to the idea of infusion. Thirdly, two models were directly compared with independent data collections occurring. Fourthly, the relationship between usage and infusion is seen to be moderated by national culture. Both the relationship as well as the moderation effects has previously been empirically shown.