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Dissertation submitted to the faculty of Commerce, Law and Management, University of the Witwatersrand, in fulfilment of the requirements for the degree of Master of Management in ICT PR / ABSTRACT Infrastructure sharing is seen an opportunity to reduce the costs of deploying infrastructure and of gearing investment towards underserviced areas. It has since emerged that there is duplication and concentration of infrastructure in urban areas and limited infrastructure in many parts of the country. This complicates the sharing of infrastructure and the effectiveness of the infrastructure sharing instruments on essential facilities, facilities leasing and interconnection regulations in granting access to a wide range of services such as voice and broadband. The purpose of this study is to explore policy and regulatory instruments in infrastructure sharing and access to broadband. The study took into account the literature on policy and regulation and infrastructure sharing, the industry views and considered the trends in infrastructure sharing and the provision of ubiquitous networks to underserviced areas. The study found that network infrastructure sharing has the potential of providing the rapid development of access infrastructure capable of handling high bandwidth requirements suitable for an information society.

Thesis (M.S.)--Brigham Young University. Dept. of Electrical and Computer Engineering, 2004. / Includes bibliographical references (p. 53-54).

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

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The ARG (Acoustic Research Group) at the University of Canterbury has a goal to image objects buried under the seafloor. In order to image these objects, accurate models and a good understanding of the acoustic parameters of the seafloor are needed. The relevant acoustic parameters to model the seafloor include: physical classification, speed of sound, acoustic impedance, density, and roughness. Acquiring accurate acoustic parameters for the seafloor is a challenging task that requires different approaches depending on the environment, especially in locations with low visibility. This thesis looks at a non-invasive method of acoustically examining the roughness spectrum and acoustic impedance of the seafloor. To achieve these goals, spherical transducers with a continuous bandwidth between 30 kHz and 130 kHz were chosen to examine the frequency dependent specular and diffused components of the reflection from rough seafloor surfaces. Using spherical transducers allows the surface scattering to be examined independently of the transducer beam-pattern. This thesis examines the range and validity of the tools required to make these measurements and presents empirical results measured in the controlled environment of a cylindrical 3.5m diameter by 2m deep sonar test tank. Using results from the sonar test tank, this thesis demonstrates that the acoustic impedance, speed of sound, and density of the material of the seafloor can be measured from a single seafloor realisation measured at multiple angles, provided the seafloor material has a critical angle. Additionally, this thesis demonstrates that the spectrum of the specular and diffused components of the rough-surface reflection requires averaging multiple seafloor realisations to be statistically relevant. As well as describing the benefits of using spherical transducers, this thesis presents some of the problems and potential solutions for future applications.

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