Hybrid DS/FH-CDMA systems employing FSK based modulation schemes.

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Title: Hybrid DS/FH-CDMA systems employing FSK based modulation schemes.
Authors: D'Amours, Claude.
Date: 1995
Abstract: This thesis examines a hybrid DS/FH-CDMA system employing FSK based modulation schemes. The proposed modulation schemes are: non-coherent MFSK, a combination of MFSK and DPSK (called MFSK-DPSK) and wideband multitone (MT) FSK. In each case, the signal to be transmitted is modulated by a high rate BPSK signal (the PN sequence) and then it is hopped at a rate higher than the symbol rate into different frequency bins that are sufficiently spaced so that the fading in each channel appears to be an independent process. The main difference between each system is that a DS/FH-CDMA system employing wideband MT-FSK must employ fewer frequency bins to have the same (or comparable) bandwidth as systems employing MFSK or MFSK-DPSK. However, the advantage gained by using MT-FSK is the inherent diversity of the modulation scheme. The bit error rate performance of each modulation scheme in a Rayleigh fading channel is found (in some cases, upper bounds are used). Both frequency-nonselective and frequency-selective fading are considered. A hybrid DS/FH-CDMA system is presented. The multiple access interference is modelled as additional white Gaussian noise. Spectral efficiency expressions are obtained for the system employing the different modulation and coding schemes considered. It is shown that the spectral efficiency of the system is inversely proportional to the bit energy to noise spectral density ratio required to achieve the maximum allowable bit error rate. Furthermore, it is shown that coded MFSK and coded MFSK-DPSK can guarantee lower bit energy to noise spectral density ratio required to achieve the maximum allowable bit error rate of 10$\sp{-3}$ than coded MT-FSK, and thus lower bounds on the spectral efficiency of DS/FH-CDMA systems employing coded MFSK or MFSK-DPSK are higher than DS/FH-CDMA systems employing coded MT-FSK.
URL: http://hdl.handle.net/10393/10366
http://dx.doi.org/10.20381/ruor-16793
CollectionTh├Ęses, 1910 - 2010 // Theses, 1910 - 2010
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