Combined turbo coding and interference rejection for DS-CDMA.
Bejide, Emmanuel Oluremi.
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This dissertation presents interference cancellation techniques for both the Forward Error Correction (FEC) coded and the uncoded Direct Sequence Code Division Multiple Access (DS-CDMA) systems. Analytical models are also developed for the adaptive and the non-adaptive Parallel Interference Cancellation (PlC) receivers. Results that are obtained from the computer simulations of the PlC receiver types confirm the accuracy of the analytical models that are developed. Results show that the Least Mean Square (LMS) algorithm based adaptive PlC receivers have bit error rate performances that are better than those of the non-adaptive PlC receivers. In the second part of this dissertation, a novel iterative multiuser detector for the Turbo coded DS-CDMA system is developed. The performance of the proposed receiver in the multirate CDMA system is also investigated. The developed receiver is found to have an error rate performance that is very close to the single user limit after a few numbers of iterations. The receiver is also resilient against the near-far effect. A methodology is also presented on the use of the Gaussian approximation method in the convergence analysis of iterative interference cancellation receivers for turbo coded DS-CDMA systems.