| Summary: | Within the last few years, improving the future W-CDMA systems by producing advanced detectors with interference suppression ability has attracted much attention. It is because in an interference-limited multiple access scheme such as W-CDMA, suppression of interference from other users in the detection of each individual user is a significant means to achieving higher capacity and enhanced quality of system performance. Although the use of highly orthogonal spreading codes and employing effective channel estimation and power control techniques mitigate the impact of interferers to a considerable extent, the growing need for further improvement in capacity and QoS in the presence of inter-cell interference and other unknown interferers forces the use of improved interference cancellation detectors at the receiver. This thesis first carries out a survey on significant existing multiuser detection and interference cancellation methods, and provides an evaluation of their performances through computer simulation of a W-CDMA uplink model which is based on UMTS standards. Then, the subject of interference cancellation is considered in this thesis from a rather different point of view. That is, narrow-band interference cancellation is examined for the purpose of studying the overlay of a W-CDMA signal by GSM carriers. In particular application of notch filters in a W-CDMA receiver is simulated and the performance of a spread spectrum system in the presence of overlaid GSM signals is evaluated in various circumstances. The impact of imperfect power control on the performance of various interference cancellation schemes is then studied through the above-mentioned UMTS-based simulation environment.
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