Mobile positioning technologies that utilize measurements of wireless communication signals are one of the most interesting topics in mobile communication systems today.; In CDMA or WCDMA based mobile communication systems, hearability is one of the most critical and practical challenges to using its wireless communication signals for positioning. Also, in practice, the repeater systems widely used for cell enhancement or covering shadowed areas in urban environments often cause hearability problem and accuracy degradation.; Therefore, solving hearability problem is a pre-requisite to building a reliable mobile positioning system. This thesis investigates the major causes of the hearability problem and proposes solution based on the thorough analysis of mobile communication system and field test results.; To understand the hearability problem, the Pilot channel searcher function in the CDMA mobile station is analyzed with its receiver operating characteristics (ROC) obtained from simulations considering practical error sources. Using knowledge of Pilot channel search performance at the mobile station, hearability is tested within a cell area where hexagonal cell geometry and practical sectorization effect is assumed.; An angle of departure (AOD) estimation scheme of the forward link signal utilizing the radiation gain patterns of sector antennas with a range measurement scheme defined in IS-95 or UMTS is proposed as a solution to the hearability problem at the inner cell area. The performance of the proposed AOD estimation scheme is shown with field test results.; Since the Pilot channel measurement at the mobile station is obtained from the measurement of the detected and resolvable earliest arrival paths for the purpose of positioning, statistical properties of the detected and resolvable earliest arrival paths and the AODs of detected and resolvable earliest arrival paths are analyzed and described before introducing the AOD field experiments.; Widely used cellular repeater systems bring another cause of hearability problem for mobile stations. This thesis introduces problems caused by repeater system and provides technical analysis of the problem. Finally, an identification signaling scheme for repeater systems is introduced as a solution; identification signal helps mobile stations distinguish repeated signals from non-repeated signals and builds an assistant location network with repeater networks.
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