Wireless location in CDMA cellular radio systems

Several issues concerning wireless location in code-division multiple-access (CDMA) communications systems are investigated in this thesis. Wireless location performance is studied and several methods are developed to mitigate the major impairments that are inherent in such systems.; For CDMA microcells and macrocells, the performance of wireless location, based on the time delay measurements provided by conventional delay estimation is studied under propagation conditions that are typical of cellular systems. From this investigation, several sources of location error are identified, including multipath propagation, multiple access interference (MAI), and non-line-of-sight (NLoS) propagation. Each of these impairments produce errors in the time delay estimates, and as a result, the location accuracy.; A new mathematical analysis of the effects of MAI on the time delay tracking performance of conventional receivers is given which avoids the assumption that the MAI can be approximated as Gaussian noise. Furthermore, a novel multiuser parameter estimation technique based on iterative nonlinear filtering is developed as a means of providing time delay estimates in MAI.; Finally, the measurement bias produced in wireless location systems in the absence of a line-of-sight (LoS) path between the mobile station (MS) and base station (BS) is analyzed to evaluate its effect on several location algorithms. A method for mitigating the errors introduced by NLoS propagation is developed and evaluated.