| Summary: | In this dissertation, we study the average performances of the coherent and non-coherent decorrelating detectors for direct-sequence spread-spectrum multiple-access communication systems. We present approximations for and bounds on the average asymptotic efficiency and the average error probability of the decorrelating detector. The averaging with respect to the random symbol delays and carrier phases results in approximations and bounds that are in terms of the well-known discrete aperiodic crosscorrelation functions of the signature sequences. For random signature sequences, these results reduce to simple expressions in terms of the basic system parameters, and are suitable for preliminary system design. We also present similar results for the average performance of a simpler one-shot version of the decorrelating detector that considers each symbol interval separately. These results show that the average performance of the one-shot decorrelator is approximately equal to the performance of a decorrelating detector with twice the number of interferers. We introduce a multiuser acquisition scheme that employs a one-shot decorrelator to cancel out the multiuser interference. Therefore, the performance of this acquisition scheme is independent of the interfering users' energies.
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