Characterizations for spread spectrum multiple-access communications with continuous-phase modulation
Abstract
Two spectrally efficient classes of direct-sequence spread-spectrum multiple-access (DS/SSMA) communication systems are examined. Characterizations for these systems are developed, which in turn allow the study of measures of the system performance. Firstly, we consider the class os DS/SSMA systems whose transmitted signals are modulated by generalized quadriphase shift-keying (GQPSK) modulation formats with arbitrarily continuous chip waveforms. The analysis made to obtain the average bit-error probability does not yield tractable solutions because of non-rectangular chip waveforms and time delays in multiple-access interferences (MAI). A method for characterizing the chip waveform and hence the MAI is developed. This method allows us to derive conditional distributions of random variables that characterize the MAI given the time delays. This characterization provides a means to tractably evaluate the average bit-error probability with arbitrary accuracy without making a Gaussian approximation. Secondly, we propose a class of DS/SSMA systems whose spectral-spreading signals possess continuous-phase modulation formats. The direct calculation of measures of the system performance is intractable, because the spectral-spreading signals have complicated signal representation. A technique for characterizing the spectral-spreading signals is developed. This characterization yields tractable expression for computing performance measures, such as the signal-to-noise ratio, the spectral density of the transmitted signal, and the BER, with arbitrary accuracy. Hence, the characterizations provide the means for the analysis and design of the proposed classes of spectrally efficient DS/SSMA systems.
Degree
Ph.D.
Advisors
Lehnert, Purdue University.
Subject Area
Electrical engineering
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