Thesis (M.S.)--Brigham Young University. Dept. of Computer Science, 2005. / Includes bibliographical references (p. 69-71).

Thesis (Ph.D.)--University of Florida, 2005. / Title from title page of source document. Document formatted into pages; contains 91 pages. Includes vita. Includes bibliographical references.

M.B.A. / This dissertation looks at E-Commerce in the South African electronic component distribution industry. With this in mind, various questions were defined and these were used to help understand the current situation, determine the future that ECommerce should have in the industry and find a mechanism to go from the current to the future situation, the questions are as follows: Has the traditional electronic component distribution channel been made obsolete by E-Commerce? What does the South African electronic component consumer want from the distributor in terms of E-Commerce? Is the communication and information technology infrastructure in South Africa adequate for the needs of E-Commerce within the electronic component industry? What are the E-Commerce models and strategies? What form and scope should E-Commerce take within the electronic component distribution industry? The research will ultimately be used as a model to help determine the E-Commerce strategy of Analog Data Products (ADP). It will enable ADP to determine if it needs to implement E-Commerce and if so at what level. The research was done using literature review to determine current trends and to seek new insights. A survey was used to verify the findings of the literature review and fill in gaps of knowledge that the literature review was unable to answer. The literature review found that there are numerous E-Commerce models, of which most fall short when compared to a generic business strategy model. It was also found that E-Commerce could often be detrimental to business. The literature also found that there are deficiencies in bandwidth in South Africa. The survey results showed that respondents are happy with the speed of E-Commerce type media, it was therefore concluded that the electronic component distribution industry is different from the norm because of its high technology nature. The survey results also showed that respondents would like to make more use of their local distributor. This indicates that the traditional distribution channel has not become obsolete. However there is a desire for more E-Commerce type transactions. These transactions should be implemented as a complement to the traditional channels rather then replacing all types of conventional business. An E-Commerce strategy should include a thorough understanding of how E-Commerce affects the value chain, which in turn will show which aspects of the chain require E-Commerce as complements and which do not.

Against the background of the rapid evolution of mobile communication systems in the areas of service provision and capacity enhancement described above, the main focus of the research is on coded space-time processing techniques. The use of space-time processing is an attractive solution because it can mitigate the effects of multipath fading as well as suppress co-channel interference, therefore, significantly improving system performance. The topics are presented in the context of designing mobile communication systems where the two core areas of spatial processing and error coding are to be integrated in an optimum way. Of particular importance in this thesis, will be those CDMA based solutions for the mobile sector and the new performance analysis issues that need to be addressed as a result of the introduction of heterogeneous services and service environments into a single, mobile cellular access network. Furthermore, novel applications of turbo transmit and receive antenna diversity and beamforming techniques to mobile cellular access networks aimed at increasing the efficiency of such networks are considered. The thesis has the following goals: • To establish a general spatial/temporal channel model for use in the evaluation of coded space-time processing concepts applied to CDMA networks. • To analyze the performance of uncoded cellular CDMA systems incorporating space-time techniques using analytical methods in a number of realistic application scenarios. • To design, implement and evaluate coding strategies for incorporation into the space-time CDMA systems. This objective can be broken down into the following items: --- Space-time coding systems when considering multiple transmit antennas for the downlink. --- Coded space-time systems when considering multiple receive antennas for the uplink. • To establish the performance of coded space-time CDMA cellular networks under realistic scenarios. This thesis introduces many (some novel) space-time turbo coded techniques to increase the downlink capacity of a cellular CDMA network using multiple transmit antennas. For improving the uplink capacity, coded space-time diversity and beamforming techniques, employing multiple receive antennas, are considered. In order to quantify the performance improvements that may be achieved, a framework for the evaluation of these systems are constructed. Using this framework the BEP of all the space-time coding systems are derived analytically, and evaluated under identical propagation scenarios. The results presented show that the use of space-time turbo coded processing is an attractive solution since it can improve system performance significantly under conditions of multipath fading for both the uplink and downlink. It is shown that the two core areas of spatial processing and channel coding can be integrated in an optimum way to increase the capacity of existing cellular CDMA networks. / Thesis (DPhil (Electronic Engineering))--University of Pretoria, 2007. / Electrical, Electronic and Computer Engineering / unrestricted

A research report submitted to the School of Economic & Business Sciences, Faculty of Commerce, Law and Management, University of the Witwatersrand in partial fulfilment of the requirements for the degree of Master of Commerce (Information Systems) by coursework / Advances in mobile technology, coupled with the explosive growth in the use of mobile devices, have seen the birth of a new organisational technology trend termed Enterprise Mobility. Enterprise mobility is where employees can work from any location other than their offices. Mobile technology use is potentially changing people’s everyday tasks and freeing individuals from tethered systems such as desktop computers. Nevertheless, the Information System (IS) field has witnessed the use and non-use of organisational technologies which has led many researchers seeking to understand what influences employees to use or not use the innovated technologies. Purpose: The study sought to describe the use of enterprise mobility application systems by individual employees in a banking environment through the theoretical lens of Task-Technology Fit (TTF) model. The goal was to determine the appropriateness and fit of enterprise mobility technologies to employees’ tasks, in the context of a South African banking environment. Design/Methodology/Approach: This is a descriptive case study following an interpretive philosophy and using a qualitative research approach. Semi-structured one-on-one interviews were administered with study participants at their offices, in a South African bank. Originality/Value: The study describes what influences the use of enterprise mobility. That is, the study extends enterprise mobility body of knowledge in the context of a banking environment. It informs practitioners with factors that may influence use and non-use of enterprise mobility application systems. Findings in Summary: Through the lenses of TTF theoretical framework the study findings reveal that, to influence individual use of enterprise mobility applications systems there should be harmony between the tasks at hand and the technologies used. The study shows that for the enterprise mobility technologies to be used, banking organisations should look on improving the underlying technology capabilities so that they are scalable to accommodate the changing user tasks requirements. The study further shows that, organisations should strike a balance between enterprise mobility and working in the office so that the essence of human interaction is not completely lost. / TL (2020)

published_or_final_version / Electrical and Electronic Engineering / Doctoral / Doctor of Philosophy

The development and performance evaluation of new techniques for direction of arrival (DOA) estimation, single-user beamforming (SUB), and multiuser beamforming (MUB) to be used in wireless communications are investigated. Two of the most commonly used beamformer configurations in direct-sequence code-division multiple access (DS-CDMA) systems, the chip-based (CB) and the symbol-based (SB) configurations for the base station (BS) receiver, are studied and their performance is evaluated. It is shown that using the CB configuration, different interfering components are rejected based on the spatial distribution of their power. In the SB configuration, spatial diversity is exploited after despreading and different interfering components are rejected based on their interfering strength which depends on both their power and code correlation with the signal of interest. For the SB configuration, more effort is applied to rejecting the interfering components with higher interfering strength and thus a more selective and efficient system is achieved. Detailed performance analysis and simulations show that in the presence of multipleaccess interference, the SB configuration can lead to a significant improvement in the signal-to-interference-plus-noise ratio relative to that achieved with the CB configuration for both asynchronous and synchronous DS-CDMA systems. A new technique for DOA estimation is proposed. The new technique, called subarray beamforming-based DOA (SBDOA) estimation, uses two virtual subarrays to form a signal whose phase relative to the reference signal is a function of the DOA. The DOA is then estimated based on the computation of the phase shift between the reference signal and the phaseshifted target signal. Since the phase-shifted target signal is obtained after interference rejection through beamforrning, the effect of co-channel interference on the estimation is significantly reduced. The proposed technique is computationally simple and the number of signal sources detectable is iii not bounded by the number of antenna elements used. Performance analysis and extensive simulations show that the proposed technique offers significantly improved estimation resolution, capacity, accuracy, and tracking capability relative to existing techniques. A new SUB algorithm is proposed for the downlink in wireless communication systems. The beam pattern at the BS is determined using a new optimality criterion which takes into consideration the fact that signals from the BS to different mobile stations (MSs) have different power and thus have different resistance to co-channel interference. In this way, the power of co-channel interference in the direction of an MS whose downlink signal has low resistance to co-channel interference can be significantly reduced. Simulation results show that the new algorithm leads to better performance than conventional algorithms in terms of system outage probability. A new MUB algorithm is proposed for joint beamforming and power control for the downlink in wireless communication systems. The optimization problem of optimal MUB is reformulated by modifying the constraints so that the weight vectors at the BS for different MSs are optimized in a feasible region which is a subset of the one of the original MUB problem. The downlink beamforming weight vectors of different MSs are then jointly optimized in a subspace instead of searching in the entire parameter space. Simulation results show that the modified optimization problem leads to solutions that satisfy the signal-to-noise-plus-interference ratio specification at each MS and, at the same time, the total power transmitted from the BS is very close to the optimal one. The solution of the modified optimization problem requires significantly less computation than that of the optimal MUB problem.

Typescript (photocopy). / Digitized by Kansas Correctional Industries

In current mobile system environment there is a large gap in the use of smart phones for personal and enterprise use due to required enterprise security policies, privacy concerns as well as freedom of use. In the current environment, data-plans on mobile systems have become so wide spread that the rate of adaptation of data plans for every day customers has far outpaced the ability for enterprises to keep up with existing secure enterprise infrastructures. Most of the enterprises require/provide the access of emails and other official information on smart platforms which presents a big challenge for the enterprise in securing their systems. Therefore due to the security issues and policies imposed by the enterprise in using the same device for dual purpose (personal and enterprise), the consumers often lose their individual freedom and convenience at the cost of security. Few solutions have been successful addressing this challenge. One effective way is to partition the mobile device such that the enterprise system access and its information are completely separated from the personal information. Several approaches are described and presented for mobile virtualization that creates a secure and secluded environment for enterprise information while allowing the user to access their personal information. A reference architecture is then presented that allows for integration with existing enterprise mobile device management systems and at the same time providing a light weight solution for containerizing mobile applications. This solution is then benchmarked with several of the existing mobile virtualization solutions. / Includes bibliography. / Dissertation (Ph.D.)--Florida Atlantic University, 2013.

by Sung Chi Wan. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1995. / Includes bibliographical references (leaves 59-[63]). / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Design Issues in Mobile Communication Systems --- p.1 / Chapter 1.2 --- Radio Resource Management --- p.2 / Chapter 1.2.1 --- Constraint: Radio Interference --- p.2 / Chapter 1.2.2 --- Objective: High Capacity and Good Quality --- p.3 / Chapter 1.3 --- Channel Assignment --- p.3 / Chapter 1.3.1 --- Static Channel Assignment --- p.4 / Chapter 1.3.2 --- Dynamic Channel Assignment --- p.5 / Chapter 1.4 --- Review of Previous Results and Motivation --- p.6 / Chapter 1.5 --- Outline of the Thesis --- p.8 / Chapter 2 --- Static Channel Assignment --- p.9 / Chapter 2.1 --- Introduction --- p.9 / Chapter 2.2 --- Problem Formulation --- p.10 / Chapter 2.3 --- Pure Co channel Interference Case --- p.12 / Chapter 2.4 --- Systems of Special Structure --- p.16 / Chapter 2.5 --- Generalization of SP --- p.22 / Chapter 2.6 --- A Lower Bound for the General Case --- p.23 / Chapter 2.7 --- Numerical Examples --- p.25 / Chapter 2.8 --- Summary --- p.29 / Chapter 3 --- Dynamic Channel Assignment --- p.30 / Chapter 3.1 --- Introduction --- p.30 / Chapter 3.2 --- Distributed Packing Algorithm --- p.31 / Chapter 3.3 --- Performance Evaluation --- p.33 / Chapter 3.4 --- Summary --- p.38 / Chapter 4 --- Single-Channel User-Capacity Calculations --- p.39 / Chapter 4.1 --- Introduction --- p.39 / Chapter 4.2 --- Capacity as a Performance Measure --- p.40 / Chapter 4.3 --- Capacity of a Linear Celluar System --- p.41 / Chapter 4.4 --- Capacity of a 3-stripe Cellular System --- p.44 / Chapter 4.5 --- Summary --- p.46 / Chapter 5 --- Conclusion --- p.47 / Chapter 5.1 --- Summary of Results --- p.47 / Chapter 5.2 --- Suggestions for Further Research --- p.48 / Appendix --- p.49 / Chapter A --- On the Optimality of Sequential Packing --- p.49 / Chapter A.1 --- Graph Multi-coloring Problem --- p.49 / Chapter A.2 --- Sequential Packing Algorithm --- p.51 / Chapter A.3 --- Optimality of Sequential Packing --- p.52 / Chapter A.4 --- Concluding Remarks --- p.55 / Chapter B --- Derivation of the Capacity of 3-stripe system --- p.56 / Bibliography --- p.59