Improvement in the performance of the CDMA radio networks

Code Division Multiple Access (CDMA) is a serious contender for fulfilling demands of future cellular mobile and personal wireless communication systems. However, there are some issues of concern which must be addressed before the implementation of such systems. CDMA system is an interference limited system and the techniques for mitigating the effects of interference is a challenging problem. Spatial processing and combining the energy in the multipaths generated by the wireless environment are the two solutions being suggested in this dissertation.; In the first part of this dissertation, we examine the role of adaptive array processing in interference suppression. A broadband system assumption is basic to this analysis. A constrained LMS algorithm for the weight selection is introduced which is a modification of the famous Frost algorithm.; In the second part, we propose a noncoherent adaptive detector. Spread spectrum signals having a large time-banwidth product provide an opportunity to recognize the multipaths. By estimating the time of arrival of these multipaths, one can extract the samples of multipaths' signals and combine them to improve the performance of the detector. The proposed suboptimal detector is based on the likelihood ratio. It automatically performs the essential portions of the decision calculation including both the processing of the received samples in each diversity branch and of combining the samples. The samples under the signal and noise condition are assumed to follow the representation theory suggested by Klose and Kurz.; In the last part of this dissertation, we assess the nature of interference in a multiple-cell system and observe that spatial processing and means of combining the multipaths contributions improve the performance of a CDMA system. Outage probability and its relation to the system capacity are calculated, keeping in mind the users' and their multipaths activities.; Computer simulations support the theoretical advantages introduced in the dissertation.