Recent trends show an increase in the availability and functionality of handheld devices, wireless network technology, and electronic display networks. We propose the novel integration of these technologies to provide wireless access to content delivered to large-screen display systems. Content adaptation is used as a method of reformatting web pages to display more appropriately on handheld devices, and to remove unwanted content. A framework is presented that facilitates content adaptation, implemented as an adaptation layer, which is extended to provide personalization of adaptation settings and response to network conditions. The framework is implemented as a proxy server for a wireless network, and handles HTML and XML documents. Once a document has been requested by a user, the HTML/XML is retrieved and parsed, creating a Document Object Model tree representation. It is then altered according to the user’s personal settings or predefined settings, based on current network usage and the network resources available. Three adaptation techniques were implemented; spatial representation, which generates an image map of the document, text summarization, which creates a tree view representation of a document, and tag extraction, which replaces specific tags with links. Three proof-of-concept systems were developed in order to test the robustness of the framework. A system for use with digital slide shows, a digital signage system, and a generalized system for use with the internet were implemented. Testing was performed by accessing sample web pages through the content adaptation proxy server. Tag extraction works correctly for all HTML and XML document structures, whereas spatial representation and text summarization are limited to a controlled subset. Results indicate that the adaptive system has the ability to reduce average bandwidth usage, by decreasing the amount of data on the network, thereby allowing a greater number of users access to content. This suggests that responsive content adaptation has a positive influence on network performance metrics.

The licence is a regulatory tool that regulatory use to assist in their regulatory functions. Licences restricts operator’s’ functions, but also serve as a guideline of acceptable conduct because a licence is a legally binding document containing prescribed conditions that the licencee must meet. If the licencee does not comply with these prescribed obligations and requirements, the licence may be revoked or the licencee may be penalized (Bladwin & Cave 1999). However, in order fro the mechanism of issuing a licence to be an effective mechanism of regulation, the regulator needs to regulate effectively in order to ensure that the licencee’s performance is of acceptable standard. The purpose of this study is to investigate the relationship between issuing a licence and the licencee’s performance; to investigate whether the performance indicators, as defined by ICASA, are adequate, and to develop appropriate performance indicators in order to evaluate Cell C’s performance. Issuing a licence to licencee does not guarantee that the performance of the licencee, such as Cell C, will be effective. Thus, the licencee needs to be evaluated. The case study design has been used for this project. The methodology includes in-dept interviews, documentary analysis, and implementation evaluation research. The report concludes that Cell C has met its licence obligations, that licencing is coupled with effective mechanisms to ensure that the licencee complies with performance requirements, but that, in order for the licencee to improve its performance, effective regulatory intervention is needed. / Communication Science / MA (International Communication)

M. Tech. Language Practice / Mobile technology has advanced to a point whereby mobile phones are no longer devices anyone can live without. Text messaging has become so popular that now there are more text messages sent by mobile phones than calls made on mobile phones. This study set out to investigate the possible effects of text messaging language on the written school work (learners' ability to properly compose and formulate) of grade 11 English first additional language learners (EFAL) at a public high school in Soshanguve, Pretoria. To this end, the two objectives of the study were to: identify if there were any instances or uses of text messaging in the written school work of grade 11 English first additional language learners at a public school in Pretoria; and establish the possible effects (positive or negative) of text messaging on grade 11 English first additional language learners' written school work.

published_or_final_version / Business Administration / Master / Master of Business Administration

Relay-assisted cooperative communications are promising solutions for error-performance improvement and cell coverage extension. In this thesis, we propose several efficient cooperative relay communication schemes. First, an efficient space-time coded cooperative relay communications scheme that employs linear precoding and transmission-pattern selection is proposed. This is built upon an existing block linear precoding technique for conventional multiple-input multiple-output systems in order to improve the diversity performance of a multihop relay network. Second, we consider several multiuser cooperative relay communication schemes employing layered modulations, such as hierarchical modulation and superposition coding. Conventional cooperative relay communication is effective in mitigating fading effects. However, additional resources, such as time slots or frequency bands are required for the relay, which reduce the overall throughput. Reduction of throughput will become more severe as the number of users increases. In order to overcome this limitation, multiuser cooperative relaying schemes that employ hierarchical modulation and superposition coding are proposed. These schemes exploit the superimposed message for users in the network and allow the system to transmit two or more independent data streams simultaneously. The proposed schemes do not require additional resources than the conventional schemes, while improving the error performance by flexibly controlling the power division coefficient of superposition coding or the distance parameter of hierarchical modulation. / Graduation date: 2012 / Access restricted to the OSU Community at author's request from Sept. 28, 2011 - Sept. 28, 2012

The objective of this dissertation is to propose the cross-layer spectrum management architecture for white space applications that improves the performance the main functions of the spectrum management. In the proposed cross-layer architecture, white space network devices such as white space devices and the spectrum map server cooperate to support the extended spectrum map, the inter-cell transmit power adaptation (ITPA), and the frequency-domain coexistence beacon (FCB). Upon the cross-layer architecture, firstly, white space devices (WSDs) achieve a faster search and higher accuracy in spectrum sensing with the extended spectrum map, the extended DHCP (Dynamic Host Configuration Protocol), and the FCB. Secondly, WSDs achieve the precise selection of their operating channel in spectrum decision with the extended spectrum map and the ITPA. In spectrum sharing, thirdly, the collaboration- based spectrum sharing with the ITPA achieve more accommodation of WSDs by increasing the number of channels shared between WSDs. Finally, WSDs with the FCB and the extended spectrum achieve effective spectrum mobility by obtaining the occupancy-status of channels precisely.

Mobile communications are becoming integrated into society at an explosive rate. While 2nd generation (2G) systems limit the user to basic services such as voice and low-bit rate data, 3G networks are characterized by their ability to accommodate wideband multi-media traffic with Quality of Service (QoS) guarantees. In the design of a system the Medium Access Control (MAC) layer is responsible for multiplexing heterogeneous traffic onto a common transmission link and its design is critical to the overall performance of a system. A number of MAC protocols for wireless networks have been proposed in the literature - the majority having time division multiple access (TDMA) at the MAC layer. However in 3G systems there is a trend towards the use of code division multiple access (CDMA) due to its proven advantages in a wireless environment. Although several papers on CDMA based MAC protocols have been published, virtually none of them tackle the analysis aspect of the protocols. Those papers that do perform analyses of CDMA protocols don't often consider heterogeneous traffic, and even fewer support QoS. The thesis addresses these shortcomings by proposing a MAC protocol that supports QoS in the form of Bit Error Rate (BER) and packet delay guarantees. The thesis begins by giving an overview of proposed wireless ATM and 3G CDMA protocols and then details how power control may be used to support BER guarantees. Various Markov based analyses are presented along with Monte-Carlo Simulations. An Equilibrium Point Analysis is then performed and the work discusses how such analyses are generally infeasible for systems supporting heterogeneous traffic. After an overview of conventional scheduling algorithms the thesis proceeds to outline a novel approach by which delay guarantees may be offered using packet dropping rates as the QoS metric. Using a stochastic source model as opposed to the conventional leaky bucket traffic regulator the thesis diverges significantly from conventional literature. The thesis also details how to calculate the probability of QoS violation and concludes with suggestions on further research avenues. As a whole the work is unique in its approach to analyse heterogeneous traffic and the methods it uses to construct session admission zones for QoS guarantees. / Thesis (Ph.D.)-University of Natal,Durban, 2002.

The emergence of portable terminals in work and living environments is accelerating the progression of wireless networks. A wireless ad hoc network is a new network concept where users establish peer-to-peer communication among themselves independently, in their small area. Since the wireless medium is a shared resource, it becomes an important design issue to efficiently allocate bandwidth among users. MAC (Medium Access Control) layer arbitrates the channel access to the wireless medium and is also responsible for bandwidth allocation to different users, therefore a large amount of research has been conducted on various MAC protocols for ad hoc wireless networks. This dissertation begins with a survey of existing wireless MAC protocols. The survey includes protocols designed for different network generations and topologies, classifying them based on architecture and mode of operation. Next, we concentrate on the MAC protocols proposed for distributed wireless networks. We propose a new MAC protocol based on a token-passing strategy; which not only incorporates the advantages of the guaranteed access scheme into the distributed type of wireless networks, but also the data rate and delay level QoS guarantees. Data rate QoS provides fairness into sharing of the channel, while delay level QoS introduces a flexible prioritized access to channels by adjusting transmission permission to the current network traffic activities. A simulation model for the protocol is developed and delay and throughput performance results are presented. To examine the efficiency and performance of the proposed MAC scheme in an ad hoc wireless environment, it is incorporated into the Bluetooth structured network. The model is then simulated in the Bluetooth environment and performance results are presented. Furthermore, an analytical model is proposed and an approximate delay analysis conducted for the proposed MAC scheme. Analytical results are derived and compared with results obtained from computer simulations. The dissertation concludes with suggestions for improvements and future work. / Thesis (M.Sc.-Engineering)-University of Natal, 2003.

Abstract available in digital copy. / Thesis (M.Sc.Eng.)-University of Natal, Durban, 2003.

Real-time information that informs transit riders about transit schedules, next bus or train arrivals, and service alerts, is becoming increasingly available, particularly through internet-enabled smartphone applications. However, the extent of communication technology usage amongst transit riders, specifically their access to mobile applications and alternative technologies that can provide real-time information, is largely unknown. Without this information, transit agencies are risking investing in an alternative technology that may not sufficiently supply real-time information to as many as possible riders. The purpose of this study is to identify the differences in individual technology accessibility and prioritize investing in real-time information application development that mirrors the unique characteristics of transit riders. This recognition and development will allow a wider availability of real-time information amongst transit riders. Paired with an investigation of cellular phone usage among transit riders and the general American population, an analysis of Saint Louis Metro’s Onboard Survey was performed. Cross tabulations and chi-squared tests were conducted to examine riders’ communication technology usage. Binary logit models were used to understand how, and whether, the ownership of smartphone applications is dependent on various demographic factors. These analyses identified specific demographic groups that would benefit from supplemental technology methods more conducive to their particular information accessibility. Results showed that communication technology usage has risen substantially in recent years but a portion of riders are still without access to smartphone applications. Specific demographic groups (e.g., riders over 40 years of age) were less likely to own smartphones, and these results indicate that computer-based websites and IVR are the best supplementary alternatives for those groups.