Browsing by Author "Densmore, Melissa"

Now showing 1 - 15 of 15
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    Open Access
    A new connectivity strategy for wireless mesh networks using dynamic spectrum access
    (2021) Maliwatu, Richard; Johnson, David; Densmore, Melissa
    The introduction of Dynamic Spectrum Access (DSA) marked an important juncture in the evolution of wireless networks. DSA is a spectrum assignment paradigm where devices are able to make real-time adjustment to their spectrum usage and adapt to changes in their spectral environment to meet performance objectives. DSA allows spectrum to be used more efficiently and may be considered as a viable approach to the ever increasing demand for spectrum in urban areas and the need for coverage extension to unconnected communities. While DSA can be applied to any spectrum band, the initial focus has been in the Ultra-High Frequency (UHF) band traditionally used for television broadcast because the band is lightly occupied and also happens to be ideal spectrum for sparsely populated rural areas. Wireless access in general is said to offer the most hope in extending connectivity to rural and unconnected peri-urban communities. Wireless Mesh Networks (WMN) in particular offer several attractive characteristics such as multi-hopping, ad-hoc networking, capabilities of self-organising and self-healing, hence the focus on WMNs. Motivated by the desire to leverage DSA for mesh networking, this research revisits the aspect of connectivity in WMNs with DSA. The advantages of DSA when combined with mesh networking not only build on the benefits, but also creates additional challenges. The study seeks to address the connectivity challenge across three key dimensions, namely network formation, link metric and multi-link utilisation. To start with, one of the conundrums faced in WMNs with DSA is that the current 802.11s mesh standard provides limited support for DSA, while DSA related standards such as 802.22 provide limited support for mesh networking. This gap in standardisation complicates the integration of DSA in WMNs as several issues are left outside the scope of the applicable standard. This dissertation highlights the inadequacy of the current MAC protocol in ensuring TVWS regulation compliance in multi-hop environments and proposes a logical link MAC sub-layer procedure to fill the gap. A network is considered compliant in this context if each node operates on a channel that it is allowed to use as determined for example, by the spectrum database. Using a combination of prototypical experiments, simulation and numerical analysis, it is shown that the proposed protocol ensures network formation is accomplished in a manner that is compliant with TVWS regulation. Having tackled the compliance problem at the mesh formation level, the next logical step was to explore performance improvement avenues. Considering the importance of routing in WMNs, the study evaluates link characterisation to determine suitable metric for routing purposes. Along this dimension, the research makes two main contributions. Firstly, A-link-metric (Augmented Link Metric) approach for WMN with DSA is proposed. A-link-metric reinforces existing metrics to factor in characteristics of a DSA channel, which is essential to improve the routing protocol's ranking of links for optimal path selection. Secondly, in response to the question of “which one is the suitable metric?”, the Dynamic Path Metric Selection (DPMeS) concept is introduced. The principal idea is to mechanise the routing protocol such that it assesses the network via a distributed probing mechanism and dynamically binds the routing metric. Using DPMeS, a routing metric is selected to match the network type and prevailing conditions, which is vital as each routing metric thrives or recedes in performance depending on the scenario. DPMeS is aimed at unifying the years worth of prior studies on routing metrics in WMNs. Simulation results indicate that A-link-metric achieves up to 83.4 % and 34.6 % performance improvement in terms of throughput and end-to-end delay respectively compared to the corresponding base metric (i.e. non-augmented variant). With DPMeS, the routing protocol is expected to yield better performance consistently compared to the fixed metric approach whose performance fluctuates amid changes in network setup and conditions. By and large, DSA-enabled WMN nodes will require access to some fixed spectrum to fall back on when opportunistic spectrum is unavailable. In the absence of fully functional integrated-chip cognitive radios to enable DSA, the immediate feasible solution for the interim is single hardware platforms fitted with multiple transceivers. This configuration results in multi-band multi-radio node capability that lends itself to a variety of link options in terms of transmit/receive radio functionality. The dissertation reports on the experimental performance evaluation of radios operating in the 5 GHz and UHF-TVWS bands for hybrid back-haul links. It is found that individual radios perform differently depending on the operating parameter settings, namely channel, channel-width and transmission power subject to prevailing environmental (both spectral and topographical) conditions. When aggregated, if the radios' data-rates are approximately equal, there is a throughput and round-trip time performance improvement of 44.5 - 61.8 % and 7.5 - 41.9 % respectively. For hybrid links comprising radios with significantly unequal data-rates, this study proposes an adaptive round-robin (ARR) based algorithm for efficient multilink utilisation. Numerical analysis indicate that ARR provides 75 % throughput improvement. These results indicate that network optimisation overall requires both time and frequency division duplexing. Based on the experimental test results, this dissertation presents a three-layered routing framework for multi-link utilisation. The top layer represents the nodes' logical interface to the WMN while the bottom layer corresponds to the underlying physical wireless network interface cards (WNIC). The middle layer is an abstract and reductive representation of the possible and available transmission, and reception options between node pairs, which depends on the number and type of WNICs. Drawing on the experimental results and insight gained, the study builds criteria towards a mechanism for auto selection of the optimal link option. Overall, this study is anticipated to serve as a springboard to stimulate the adoption and integration of DSA in WMNs, and further development in multi-link utilisation strategies to increase capacity. Ultimately, it is hoped that this contribution will collectively contribute effort towards attaining the global goal of extending connectivity to the unconnected.
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    Open Access
    Babel's Tower: South Africa's Wikipedias
    (2019) Graaf, Michael; Densmore, Melissa; Johnson, D
    This dissertation is a comparative examination firstly of usage of, and contribution to, the Wikipedias in ten of South Africa’s eleven official languages, and secondly of possible measures to address the situation discovered in the first investigative stage. The historical context is reviewed and it is argued that the number of official languages (and therefore Wikipedias) results from decisions made in colonial and apartheid eras. Public-domain usage and contribution statistics from the Wikimedia Foundation are analysed, revealing poor growth in most cases; possible interventions via both cultural/educational strategies and technological options are reviewed.
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    Open Access
    Channel parameter tuning in a hybrid Wi-Fi-Dynamic Spectrum Access Wireless Mesh Network
    (2023) Zlobinsky, Natasha; Densmore, Melissa; Mishra, Amit
    This work addresses Channel Assignment in a multi-radio multi-channel (MRMC) Wireless Mesh Network (WMN) using both Wi-Fi and Dynamic Spectrum Access (DSA) spectrum bands and standards. This scenario poses new challenges because nodes are spread out geographically so may have differing allowed channels and experience different levels of external interference in different channels. A solution must meet two conflicting requirements simultaneously: 1) avoid or minimise interference within the network and from external interference sources, and 2) maintain connectivity within the network. These two requirements must be met while staying within the link constraints and the radio interface constraints, such as only assigning as many channels to a node as it has radios. This work's original contribution to the field is a unified framework for channel optimisation and assignment in a WMN that uses both DSA and traditional Wi-Fi channels for interconnectivity. This contribution is realised by providing and analysing the performance of near-optimal Channel Assignment (CA) solutions using metaheuristic algorithms for the MRMC WMNs using DSA bands. We have created a simulation framework for evaluating the algorithms. The performance of Simulated Annealing, Genetic Algorithm, Differential Evolution, and Particle Swarm Optimisation algorithms have been analysed and compared for the CA optimisation problem. We introduce a novel algorithm, used alongside the metaheuristic optimisation algorithms, to generate feasible candidate CA solutions. Unlike previous studies, this sensing and CA work takes into account the requirement to use a Geolocation Spectrum Database (GLSD) to get the allowed channels, in addition to using spectrum sensing to identify and estimate the cumulative severity of both internal and external interference sources. External interference may be caused by other secondary users (SUs) in the vicinity or by primary transmitters of the DSA band whose emissions leak into adjacent channels, next-toadjacent, or even into further channels. We use signal-to-interference-plus-noise ratio (SINR) as the optimisation objective. This incorporates any possible source or type of interference and makes our method agnostic to the protocol or technology of the interfering devices while ensuring that the received signal level is high enough for connectivity to be maintained on as many links as possible. To support our assertion that SINR is a reasonable criterion on which to base the optimisation, we have carried out extensive outdoor measurements in both line-of-sight and wooded conditions in the television white space (TVWS) DSA band and the 5 GHz Wi-Fi band. These measurements show that SINR is useful as a performance measure, especially when the interference experienced on a link is high. Our statistical analysis shows that SINR effectively differentiates the performance of different channels and that SINR is well correlated with throughput and is thus a good predictor of end-user experience, despite varying conditions. We also identify and analyse the idle times created by Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) contention-based Medium Access Control (MAC) operations and propose the use of these idle times for spectrum sensing to measure the SINR on possible channels. This means we can perform spectrum sensing with zero spectrum sensing delay experienced by the end user. Unlike previous work, this spectrum sensing is transparent and can be performed without causing any disruption to the normal data transmission of the network. We conduct Markov chain analysis to find the expected length of time of a sensing window. We also derive an efficient minimum variance unbiased estimator of the interference plus noise and show how the SINR can be found using this estimate. Our estimation is more granular, accurate, and appropriate to the problem of Secondary User (SU)-SU coexistence than the binary hypothesis testing methods that are most common in the literature. Furthermore, we construct confidence intervals based on the probability density function derived for the observations. This leads to finding and showing the relationships between the number of sampling windows and sampling time, the interference power, and the achievable confidence interval width. While our results coincide with (and thus are confirmed by) some key previous recommendations, ours are more precise, granular, and accurate and allow for application to a wider range of operating conditions. Finally, we present alterations to the IEEE 802.11k protocol to enable the reporting of spectrum sensing results to the fusion or gateway node and algorithms for distributing the Channel Assignment once computed. We analyse the convergence rate of the proposed procedures and find that high network availability can be maintained despite the temporary loss of connectivity caused by the channel switching procedure. This dissertation consolidates the different activities required to improve the channel parameter settings of a multi-radio multi-channel DSA-WMN. The work facilitates the extension of Internet connectivity to the unconnected or unreliably connected in rural or peri-urban areas in a more cost-effective way, enabling more meaningful and affordable access technologies. It also empowers smaller players to construct better community networks for sharing local content. This technology can have knock-on effects of improved socio-economic conditions for the communities that use it.
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    Open Access
    Co-Designing with and for Milk Donors
    (2019) Wardle, Chelsea-Joy; Densmore, Melissa
    Many mothers of small children (<2 years old) rely on technological interventions to provide aid and advice for child-rearing during the early stages of motherhood. This time can feel very isolating and so many mothers turn to technology as a medium to reach others and access information. In this research, I examine South African mothers’ experience with computer-supported aid for online communication and information searching. I describe these mothers in the context where they are also milk donors and provide insight into their utilization and preferences for social networks through the lens of co-designing with them a donor mother chatroom for improved communication between donor mothers and the NGO. Breastfeeding mothers who want to become milk donors have to go through a rigorous screening process to qualify to be a human milk donor. The lack of feedback from Milk Matters and the demanding donation process deters mothers from donating, especially considering the existing constraints of mother resources. The transition to becoming a mother can be very stressful, isolating and challenging, even more so as a donor. Through this work I identify several design implications to consider when co-designing a chatroom with donor mothers, for donor mothers with the purpose of improving engagement and feedback between them and the milk bank. Designing mobile applications for breastfeeding mothers can be challenging; creating spaces to foster co-design – when a mother’s primary focus is on her child rather than on design activities – is even more so. Based on this knowledge, I have approached this study with a variety of co-design methods, comparing Cultural Probes, interviews, participant observation, high- and low-fidelity prototyping, and cognitive walkthroughs.
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    Open Access
    Designing with community health workers: feedback-integrated multimedia learning for rural community health
    (2018) Molapo, Maletsabisa; Densmore, Melissa
    Community Health Workers (CHWs) are an integral part of the rural health system, and it is imperative that their voices are accommodated in digital health projects. In the mobile health education project discussed in this thesis (The Bophelo Haeso project), we sought to find ways to amplify CHWs' voices, enabling them to directly influence design and research processes as well as technological outcomes. The Bophelo Haeso (BH) project equips CHWs with health videos on their mobile phones to use for educating and counselling the rural public. We investigated how to best co-design, with CHWs, a feedback mechanism atop the basic BH health education model, thus enabling their voices in the design process and in the process of community education. This thesis chronicles this inclusive design and research process - a 30-month process that spanned three sub-studies: an 18-month process to co-design the feedback mechanism with CHWs, a 12-month deployment study of the feedback mechanism and, overlapping with the feedback deployment study, a 17-month study looking at the consumption patterns of the BH educational videos. This work contributes to the field of Human Computer Interaction (HCI) in three distinct ways. First, it contributes to the growing knowledge of co-design practice with participants of limited digital experience by introducing a concept we termed co-design readiness. We designed and deployed explorative artefacts and found that by giving CHWs increased technical, contextual, and linguistic capacity to contribute to the design process, they were empowered to unleash their innate creativity, which in turn led to more appropriate and highly-adopted solutions. Secondly, we demonstrate the efficacy of incorporating an effective village-to-clinic feedback mechanism in digital health education programs. We employed two approaches to feedback - asynchronous voice and roleplaying techniques. Both approaches illustrate the combined benefits of implementing creative methods for effective human-to-technology and human-tohuman communication in ways that enable new forms of expression. Finally, based on our longitudinal study of video consumption, we provide empirical evidence of offline video consumption trends in health education settings. We present qualitative and quantitative analyses of video-use patterns as influenced by the CHWs' ways of being and working. Through these analyses, we describe CHWs and their work practices in depth. In addition to the three main contributions, this thesis concludes with critical reflections from the lessons and experiences of the 30-month study. We discuss the introduction of smartphones in rural villages, especially among elderly, low-literate, and non-English-speaking users, and present guidelines for designing relevant and usable smartphones for these populations. The author also reflects on her position as an African-born qualitative researcher in Africa, and how her positionality affected the outcomes of this research.
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    Exploring undergraduate interactions with mobile privacy and security
    (2018) Till, Sarina; Densmore, Melissa
    Many studies have proven that digital natives are not as tech-savvy as previously thought, and possibly vulnerable in terms of privacy and security. My focus was to characterise how this generation interacted with mobile privacy and security. We provide evidence from a cohort of South African students, using this to discuss areas in which they need to be protected. We employed a web-based survey of 77 students, supplemented by in-depth interviews with 10 additional students. In both cases, we enquired about knowledge of permissions, encryption and application installation practices. With the in-depth interviews we also observed students as they installed two applications, one of which over-requested permissions. Our findings showed that most students (80%) did not look for- or understand permissions, did not understand or look for encryption, and used location-based services unsafely. Based on these results, we argue that digital natives lack the technical skills to properly engage with mobile privacy and security. Furthermore, digital natives do not understand mobile security and privacy features and therefore ignore them. Digital natives trust the authors of software and fail to act securely when security and privacy features are requested out of context. We further argue that this generation of digital natives has been so overexposed to mobile requests that violate their privacy and security that they have become desensitised to them. We further argue that digital natives’ definition of privacy is different from that of previous generations. Lastly, we discuss the implications of our findings for Higher Education Institutions, Higher Education Policy and mobile application design.
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    Improving content delivery in low-resource networks: a case study of the African Internet Ecosystem
    (2021) Phokeer, Amreesh Dev; Johnson, David; Densmore, Melissa
    The Internet is one of the most successful inventions of recent times. The COVID-19 pandemic has, once again, proven the importance of the Internet to society, and this has further demonstrated how critical it is to build networks that are resilient, accessible and inclusive. However, the Internet in many African countries is still limited by both technical and regulatory challenges. It is along these lines that this thesis proposes a series of studies, supported by empirical evidence, to better understand the challenges of content delivery in African networks. The thesis starts by providing an understanding how the Internet is being used and consumed by low-income mobile Internet users in South African townships. By means of a mixed-methods study, combining quantitative network measurements with qualitative survey data, the thesis provides some useful insights about Internet usage patterns and the underlying reasons for specific user behaviour with regards to mobile data management. The research revealed how Internet usage patterns of users in low-resource settings are restrained by the lack of access, availability of services and data cost.It also reinforced the concept of locality of interest and at the same time showing that the mainstream Internet services remain very popular. Next, the thesis investigates the impediments faced by African users to access local content and cloud-based services. This is achieved through a study on web content hosting, focusing specifically on African local news and public sector websites. It was found that 85% of local news websites are hosted outside their respective countries by foreign companies, mostly in Europe and in the US. This section revealed how a majority of Africa's local content is still hosted remotely and this has a major incident on the Quality of Experience (QoE) of users in Africa. Considering the set of challenges of content delivery in Africa, companies such as Facebook and Google have introduced alternative mechanisms to deliver content to the end-user - purportedly using bandwidth-friendly and cost-effective technologies. This thesis performs an in-depth Quality of Service (QoS) analysis of: (1) Free Basics, a “zero-rated” service from Facebook and (2) Accelerated Mobile Pages (AMP), a mobile optimisation technology by Google. The aim of both Free Basics and AMP is to reduce the cost of access and improve the QoE on mobile devices through different techniques - albeit with some caveats pertaining to net neutrality and data privacy. However, the thesis reveals that Free Basics services provide weaker network performance than their paid counterparts, which contributes to a disjointed user experience. On the other hand, Google AMP pages can reduce traditional page sizes by a factor of 8 and the results show that Page Load Time (PLT) on African networks can significantly be improved. However, both Free Basics and Google AMP introduce serious concerns with regards to net neutrality and data privacy. One way to minimise the effects of cross-continental path is to host the content as close as possible to the end-users. For this, there must exist a robust interconnection ecosystem between African networks. The thesis performs a deep-dive in both intra-country and inter-country connectivity in Africa, looking into both delays and network path by means of a longitudinal active measurement study. The latter exposes interesting topological characteristics of cross-border connectivity and provides evidence on the existence of circuitous routing and a lack of peering within African networks. The thesis reveals a series of “communities”, in which countries have built up low-delay interconnectivity, dispelling the myth that intra-delays in Africa are universally poor. Finally and taking into account the above, the thesis studies how the development of localised Internet infrastructure such as Internet Exchange Points (IXPs) and Data Centres (DCs) can help democratise access to local content. Using a simple multi-level maturity model, the thesis categorises the readiness of African countries to provide a localised Internet infrastructure. The thesis further explores the above hypothesis by estimating the effect of increasing the number of participants of an IXP on the local content activity of the country. The latter was achieved by using a fixed-effects econometric model and a positive correlation was found between the scale of an IXP and the local content activity. The thesis finally provides some key policy points on how to improve content delivery in African networks.
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    Improving Pan-African research and education networks through traffic engineering: A LISP/SDN approach
    (2017) Chavula, Josiah; Suleman, Hussein; Densmore, Melissa
    The UbuntuNet Alliance, a consortium of National Research and Education Networks (NRENs) runs an exclusive data network for education and research in east and southern Africa. Despite a high degree of route redundancy in the Alliance's topology, a large portion of Internet traffic between the NRENs is circuitously routed through Europe. This thesis proposes a performance-based strategy for dynamic ranking of inter-NREN paths to reduce latencies. The thesis makes two contributions: firstly, mapping Africa's inter-NREN topology and quantifying the extent and impact of circuitous routing; and, secondly, a dynamic traffic engineering scheme based on Software Defined Networking (SDN), Locator/Identifier Separation Protocol (LISP) and Reinforcement Learning. To quantify the extent and impact of circuitous routing among Africa's NRENs, active topology discovery was conducted. Traceroute results showed that up to 75% of traffic from African sources to African NRENs went through inter-continental routes and experienced much higher latencies than that of traffic routed within Africa. An efficient mechanism for topology discovery was implemented by incorporating prior knowledge of overlapping paths to minimize redundancy during measurements. Evaluation of the network probing mechanism showed a 47% reduction in packets required to complete measurements. An interactive geospatial topology visualization tool was designed to evaluate how NREN stakeholders could identify routes between NRENs. Usability evaluation showed that users were able to identify routes with an accuracy level of 68%. NRENs are faced with at least three problems to optimize traffic engineering, namely: how to discover alternate end-to-end paths; how to measure and monitor performance of different paths; and how to reconfigure alternate end-to-end paths. This work designed and evaluated a traffic engineering mechanism for dynamic discovery and configuration of alternate inter-NREN paths using SDN, LISP and Reinforcement Learning. A LISP/SDN based traffic engineering mechanism was designed to enable NRENs to dynamically rank alternate gateways. Emulation-based evaluation of the mechanism showed that dynamic path ranking was able to achieve 20% lower latencies compared to the default static path selection. SDN and Reinforcement Learning were used to enable dynamic packet forwarding in a multipath environment, through hop-by-hop ranking of alternate links based on latency and available bandwidth. The solution achieved minimum latencies with significant increases in aggregate throughput compared to static single path packet forwarding. Overall, this thesis provides evidence that integration of LISP, SDN and Reinforcement Learning, as well as ranking and dynamic configuration of paths could help Africa's NRENs to minimise latencies and to achieve better throughputs.
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    Investigating the Usability and Quality of Experience of Mobile Video-Conferencing Apps Among Bandwidth-Constrained Users in South Africa
    (2022) Oosthuizen, Dominique; Densmore, Melissa
    In response to Covid-19 and global lockdowns, we have seen a surge in video-conferencing tools' usage to enable people to work from home and stay connected to family and friends. Although understanding the performance and the perceived quality of experience for users with bandwidth caps and poor internet connections could guide the design of video-conferencing apps, the usability of video-conferencing applications have been severely overlooked in developing countries like South Africa, where one-third of adults rely on mobile devices to access the internet and where the per-gigabyte data cost is some of the most expensive in Africa. Considering these numbers, we conduct a two-prong study where 1) we measure bandwidth consumption of different Android apps through bandwidth measurement experiments and 2) we conduct interviews with bandwidth-constrained users to better understand their perceptions of mobile videoconferencing apps. The key benefit of this study will be to inform organisations that seek to be inclusive about these tools' relative usability by letting them know about the factors influencing users' quality of experience.
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    Modelling evolving clinical practice guidelines: a case of Malawi
    (2018) Msosa, Yamiko Joseph; Keet, C Maria; Densmore, Melissa
    Electronic medical record (EMR) systems are increasingly being adopted in low- and middle-income countries. This provides an opportunity to support task-shifted health workers with guideline-based clinical decision support to improve the quality of healthcare delivery. However, the formalization of clinical practice guidelines (CPGs) into computer-interpretable guidelines (CIGs) for clinical decision support in such a setting is a very challenging task due to the evolving nature of CPGs and limited healthcare budgets. This study proposed that a CIG modelling language that considers CPG change requirements in their representation models could enable semi-automated support of CPG change operations thereby reducing the burden of maintaining CIGs. Characteristics of CPG changes were investigated to elucidate CPG change requirements using CPG documents from Malawi where EMR systems are routinely used. Thereafter, a model-driven engineering approach was taken to design a CIG modelling framework that has a novel domain-specific modelling language called FCIG for the modelling of evolving CIGs. The CIG modelling framework was implemented using the Xtext framework. The national antiretroviral therapy EMR system for Malawi was extended into a prototype with FCIG support for experimentation. Further studies were conducted with CIG modellers. The evaluations were conducted to answer the following research questions: i) What are the CPG change requirements for modelling an evolving CIG? ii) Can a model-driven engineering approach adequately support the modelling of an evolving CIG? iii) What is the effect of modelling an evolving CIG using FCIG in comparison with the Health Level Seven (HL7) standard for modelling CIGs? Data was collected using questionnaires, logs and observations. The results indicated that finegrained components of a CPG are affected by CPG changes and that those components are not included explicitly in current executable CIG language models. The results also showed that by including explicit semantics for elements that are affected by CPG changes in a language model, smart-editing features for supporting CPG change operations can be enabled in a language-aware code editor. The results further showed that both experienced and CIG modellers perceived FCIG as highly usable. Furthermore, the results suggested that FCIG performs significantly better at CIG modelling tasks as compared to the HL7 standard, Arden Syntax. This study provides empirical evidence that a model-driven engineering approach to clinical guideline formalization supports the authoring and maintenance of evolving CIGs to provide up-to-date clinical decision support in low- and middle-income countries.
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    Performance analysis of hybrid WiFi and TV white space links
    (2020) Lamola, Mokwape Magdeline; Johnson, David Lloyd; Densmore, Melissa; Lysko, Albert
    Internet access has the potential to improve economic growth in developing countries, yet in developing countries with emerging economies, such as South Africa, Internet access opportunities are not evenly distributed. This digital divide exists between urban and rural areas and even within urban areas in many developing countries. Urban areas are densely populated - simplifying telecommunication infrastructure roll-out, whereas rural areas are sparsely populated - making the roll-out of telecommunication infrastructure considerably more complex and expensive. This digital divide poses a significant challenge since a large portion of the developing country's population is based in rural areas. Cellular, satellite and some pockets of WiFi technologies are mostly used to provide access in rural areas. Although these technologies help mitigate connectivity challenges in rural areas, they are often costly and provide limited broadband access. The high cost of access in rural areas is due to the lack of fibre for backhaul that provides cost effective bulk wholesale capacity and the use of costly satellite links or cellular links for Internet access. Cost-effective technology alternatives such as WiFi and/or Television White Space (TVWS) can provide an effective approach to provide affordable last mile and middle mile connectivity for Internet access in many of these poorly connected areas. TVWS provides excellent coverage and penetration through vegetation, buildings since it utilizes spectrum in the UHF bands currently used for Television broadcasting to offer broadband wireless connectivity. Although TVWS has good propagation characteristics in some non-line-ofsight (NLOS) scenarios and can offer better coverage than WiFi, thanks to the mass production and massive industry and development support behind it, WiFi provides low-cost connectivity with better throughput speeds in line-of-sight (LOS) scenarios. Previous research has focused on the characteristics and performance of TVWS and WiFi in isolation. This study aims to describe how their individual characteristics can then be used to compliment each other for improvement in the last-mile access. This work looked at the performance of WiFi and TVWS technology in different settings, including line-of-sight, non-line-of-sight environments and using different combinations of these technologies. Experiments focused on the performance of WiFi (IEEE 802.11a) and TVWS (IEEE 802.11g cards downconverted to UHF) with an objective to help improve connectivity in areas with poor coverage, due to environmental factors, such as vegetation and distance. The study utilized the Council of Scientific and Industrial Research's (CSIR's) Meraka Institute custom built White Space Mesh Node (WSMN) equipped with WiFi and TVWS radio interface cards to carry out the experiments. The study particularly focuses on the 5 GHz Wi-Fi and Ultra High Frequency (UHF) 530 to 600 MHz frequency bands. The study presents an analysis of data collected over the dual-radio wireless network in indoor and outdoor environments. Presentation of this data follows measurements of single radio and aggregate radio link traffic collected in various line-of-sight and non-line-of-sight environments. These measurements deduce the effects of environment on 5 GHz and TVWS frequency band, effects of modifying performance parameters, improvement or degradation of aggregated TVWS WiFi links, and the usage of the measured performance data for network planning. Each experiment tests different combinations of radio settings, such as channel, transmit power and channel width to measure throughput, signal strength, packet loss, and Signal to Noise Ratio. These tests were done in both indoor and outdoor environments. The results collected and presented in this work show that although TVWS has superior propagation characteristics compared to WiFi, its performance is often poorer than WiFi when there is clear line-of-site and at shorter distances. The study, in addition, presents data that shows that the overall radio performance in a network is affected by more than just spectrum availability in space or time, but also by radio settings and the environment. The study also goes on to show that aggregated links, that combine both TVWS and WiFi, do not always lead to better network performance. The study lastly presents tailored scenarios of single and aggregated radio links that lead to better performance with the hope that these will help network designers and researchers make better-informed decisions on how to use available radio resources effectively.
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    Open Access
    Preemie Care: A Co-designed Digital Tool to Improve Communication Between Health Personnel and Parents of Preterm Infants
    (2022) Mburu, Christine Wanjiru; Densmore, Melissa; Joolay,Yaseen
    Communication between parents and health providers is essential in the Neonatal Intensive Care Unit (NICU) settings to ensure both parties collaborate in infant care. However, in most NICUs, the interaction between parents and NICU staff is strained, thus hindering communication. These communication challenges are due to language, medical vocabulary and cultural barriers between NICU staff and mothers. These challenges create communication gaps, which disempower parents and frustrate health staff. To bridge NICU communication gaps, several researchers have deployed digital health interventions. However, although the existing NICU technologies have effectively improved NICU communication, most parents struggle to interact with these interventions because they do not fit parents' technical and literacy capabilities. These design gaps arise because parents were not fully included in the design process of the existing NICU digital interventions. In this research, we sought to address the communication gaps within the NICU environment by employing a co-design approach to develop a digital intervention that supports infant care journey in a low-resource NICU setting. The co-design process included six research phases that spanned over 32 months. We engaged mothers of premature infants and NICU staff throughout this process while focusing on identifying how best to involve NICU stakeholders in a codesign process to ensure that the final intervention was usable and useful. The co-design process led to the development of MoM connect workflow which was disqualified by mothers and NICU staff because it did not meet mothers' needs. We further engaged NICU stakeholders in the co-design process and agreed on developing Preemie Care (PMC) system, an educational resource tool that disseminated digital health videos in multiple languages and through multiple technologies to empower parents and NICU staff to work together and advocate for their preterm infants. PMC system was deployed at Groote Schuur NICU for eight months where we interacted with users and monitored it usage logs to evaluate its efficacy. Our empirical evidence revealed that access to health information improved parents and their social networks medical vocabulary, thus empowering them to engage with their peers and NICU staff. We also learned that sharing health information in multiple languages does not resolve the language barriers among multilingual NICU parents. Instead, our results show that bilingual parents prefer accessing health information in multiple languages to improve their medical vocabulary and understandability, thus empowering them to engage in their infants' health care and decision-making. Hence, this research provides the design mechanisms for a NICU intervention to bridge communication gaps between bilingual parents and NICU staff. This work contributes to the field of Human-Computer Interaction(HCI) by highlighting the ethical and methodological considerations to engage NICU stakeholders interacting in a sensitive NICU setting in a collaborative co-design process. We also contribute to HCI knowledge by providing design mechanisms for a NICU intervention meant to bridge communication gaps between bilingual parents and NICU staff in a low-resource setting and design features of a digital NICU intervention that enhance family-centred care in the NICU setting.
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    Reflections on Digital Maternal and Child Health Support for Mothers and Community Health Workers in Rural Areas of Limpopo Province, South Africa
    (Multidisciplinary Digital Publishing Institute, 2023-01-19) Muthelo, Livhuwani; Mbombi, Masenyani Oupa; Bopape, Mamare Adelaide; Mothiba, Tebogo M.; Densmore, Melissa; van Heerden, Alastair; Norris, Shane A.; Dias, Nervo Verdezoto; Griffiths, Paula; Mackintosh, Nicola
    Introduction: Digital health support using mobile and digital technologies, such as MomConnect and WhatsApp, is providing opportunities to improve maternal and child healthcare in low- and middle-income countries. Yet, the perspective of health service providers, pregnant women, and mothers as recipients of digital health support is under-researched in rural areas. Material and Methods: An exploratory-descriptive qualitative research approach was adopted to reflect on the experiences of mothers, community leaders, and community health workers on mobile health opportunities in the context of maternal and child health in rural areas. Purposive sampling was used to select 18 participants who participated in the two focus groups and individual semi-structured interviews for data collection about digital maternal and child health support. The thematic open coding method of data analysis assisted authors in making sense of the given reflections of mothers, community leaders, and healthcare workers about digital health support. Results: Participants commented on different existing digital support apps and their importance for maternal and child health. For example, MoMConnect, Pregnancy+, WhatsApp, and non-digital resources were perceived as useful ways of communication that assist in improving maternal and child health. However, participants reported several challenges related to the use of digital platforms, which affect following the health instructions given to pregnant women and mothers. Conclusions: Participants expressed the significant role of digital support apps in maternal and child health, which is impacted by various challenges. Addressing the lack of digital resources could improve access to health instructions for pregnant women and mothers.
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    Understanding alignment between design approaches and student priorities for online learning platforms
    (2021) Jian, Xue Jun; Densmore, Melissa
    With the increasing number of public institutions turning to online learning, there is a need to understand the process of online learning development and how it aligns with student priorities for online learning platforms. This is exacerbated by the onset of COVID-19, with many institutions hastening to move their courses online during the global lockdowns, making it even more a priority to understand online learning practice. Various studies have reported on best online learning practices but deviations from student priorities still exist in reality. In practice, courses are predominantly designed from the lecturer's perspective, and student perspectives are only incorporated through feedback from course evaluations. Students are rarely given a role in the design process and are therefore unable to sculpt out their design needs for online courses. One design approach which gives a design role to students is co-design. Codesign takes into account the perspectives of all stakeholders by allowing each stakeholder to equally participate in the design process. The participation of students in design and the degree of participation they take has rarely been articulated. How does the design approach from the lecturer's perspective, where students take no part in the design process, compare to the co-design approach, where maximum participation can be achieved? How do these design approaches contribute to the deviations from student priorities? The aim of this study was to understand the alignment between design approaches and student priorities for online learning platforms and how deviations transpire. This research posited that a co-design approach, including the students as designers, might assist in alleviating these deviations. In the first part of the study, the researcher interviewed current students in an online course to understand their priorities for design. Results from the interviews were analysed and shared with students and lecturers, who were invited to prototype designs for a lesson module based on this feedback, first individually, then as a group. Another set of students were then invited to compare and evaluate the implemented prototypes in the final part of the study. The results demonstrated that a) expressed student learning priorities generally aligned with current knowledge of online learning design, b) a gap between design and reality exists for actual online course practices, c) design deviations from student priorities emerged at the beginning stages of the design process, where individual interpretation of design needs differed, d) design discussions and idea sharing during co-design alleviated these deviations, and e) co-design activities stunted the creativity of the team. Although co-design managed to bridge part of the gap between online learning platform design and student priorities, there are many factors that limit effective multistakeholder co-design. Depending on characteristics of individuals, team dynamics and design environment and conditions, the full benefits of co-design may not always be realized. Future works should explore ways of gaining mainstream adoption of design approaches such as co-design, to bridge the gap between design and reality in the online learning space.
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    Utilization of personal health informatics through intermediary users
    (2018) Katule, Ntwa; Densmore, Melissa; Rivett, Ulrike
    Personal informatics are important tools in health self-management as they support individuals to quantify and self-reflect on their lifestyle. Human-computer interaction researchers have devoted resources on studying how to design such tools. Various motivational strategies have been explored for their capabilities in improving user engagement. However, such strategies are developed with an assumption that the targeted consumer of information is the one directly manipulating user interfaces of the system that has information. This may not always be the case for users in developing regions. As a result, such systems may not scale well in contexts where a targeted consumer (beneficiary) may use technology through the facilitation of another person (intermediary) whom is responsible for manipulating user interfaces, because such facilitators are not recognized as part of the system, hence motivational strategies don't cater for them. In order to uncover design implications for intermediated technology use in the context of personal health informatics (PHI), the researcher started with the theoretical framing of the work followed by a contextual enquiry which led to development of mobile applications' prototypes for tracking nutrition and physical activity. Evaluation of the prototypes revealed that a familial relationship is a prerequisite for such an intervention. The most promising combination involves family members, possibly a child and a parent working together. The study used self-determination theory to understand how a collaborative gamified system can increase engagement. The result revealed that gamification as the source of a significant increase in perceived competence in intermediary users whom also tended to consider themselves as co-owners of the interaction experience. Therefore, gamification was found to be a catalyst for increasing collaboration between an intermediary and beneficiary user of technology, provided that the two users that formed a pair had a prior social relationship. In the absence of gamification, intermediary users tended to be less engaged in the intervention. The study highlights both the positive and negative aspects of gamification in promoting collaboration in intermediated use and its general implications in health settings. Design considerations required in order to improve the overall user experience of both users involved are proposed. In general, this work contributes to both theory and empirical validation of factors for, supporting proximate-enabled intermediated use of personal health informatics.