The increasing demand for greater capacity of mobile communications has led to the petition of more radio spectrum at 1900 MHz for the new personal communication service (PCS) systems. The PCS spectrum is proposed to coexist with current fixed microwave spectrum. This presents cochannel interference control problems which can be avoided with extensive propagation studies in both measurements and predictions. Currently, there is no readily available tool to predict propagation channels for the small coverage area that PCS operates at 1900 MHz. This thesis presents new methods for propagation prediction without relying on measurements but rather local environment geometries and their electrical properties. The propagation prediction tool developed is based on the principle of geometrical optics and Fresnel-Kirchoff diffraction. Geometrical optics enables computer software to automatically trace the propagation of radio wave energy from the transmitter to the receiver. The ray tracing techniques presented are optimized for speed with a little trade-off in accuracy. Also, efficient techniques were developed to find true diffracting building edges in dense urban environments. The propagation prediction software also rely on other commercial software packages such as AutoCAD and GRASS to maintain and manipulate the environmental database as well as displaying prediction results. The software yielded reasonable accuracy when compared against VT campus propagation measurements at 900 MHz and 1900 MHz. / Master of Science

University of Macau / Faculty of Social Sciences and Humanities / Department of Communication

Thesis (MSc (Geography and Environmental Studies))--University of Stellenbosch, 2005. / The substantial growth of the Internet during the past few years has sparked the adaptation of several fields of current technologies to its demanding and cutting-edge standards. Mobile wireless cellular engineering and Geographic Information Systems (GIS) are two such technologies. Integrating these two technologies has resulted in the possibility of providing a type of useful functionality in the form of a technological service to the public in terms of their geographical location, named Location Based Services (LBS). An LBS can be defined as any service or application that extends spatial information processing or GIS capabilities to end users via the Internet and/or wireless networks. Thanks to wireless cellular engineering, GIS, computer programming and a little intellectual ingenuity, LBS now has the ability to provide a solution to the persisting problem of the intractable incapability of prevalent technology to extend utile spatial information to a user in terms of his/her geographical location. The purpose of this study is to investigate how geographical information, derived from GIS processing, can be supplied and presented in a useful manner to users' mobile electronic devices, using today’s available technology. A sample LBS application will demonstrate how this is achieved in the South African context. It includes features such as position location, street finding, shortest street route calculation, and map display, all on a mobile cellular device. Relevant issues such as impending wireless cellular technology, development cycles, implementation, costs, revenues and shortcomings are also discussed.