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Coherent and noncoherent DS/SSMA communications with complex signature sequences: Error and acquistion performances
This dissertation is a study of error and acquisition performances of direct-sequence spread-spectrum multiple-access (DS/SSMA) systems. The problems investigated in this dissertation are: (i) probability of bit error performances of DS/SSMA systems with M-ary phase-shift-keyed (MPSK) signaling; (ii) probability of bit error performances of DS/SSMA systems with noncoherent signaling schemes; (iii) acquisition performances of DS/SSMA systems. All analyses apply to complex as well as binary signature sequences. A bounding technique was used to obtain arbitrarily tight upper and lower bounds on the probability of bit error (p.b.e.) for DS/SSMA systems with MPSK signaling. The two dimensional probability density function (p.d.f.) of the complex multiple user interference (MUI) is derived for deterministic sequences. Using appropriate shifting procedures on the p.d.f., upper and lower bounds are obtained. Numerical results are given for binary PSK (BPSK), 4-PSK, and 8-PSK signalings using examples of binary as well as complex sequences. Results show that complex sequences can yield better performance than binary sequences in MPSK signaling. P.b.e. performances of DS/SSMA systems using noncoherent signaling schemes is investigated. Differential-phase-shift-keyed (DPSK) signaling and noncoherent frequency-shift-keyed (FSK) signaling are considered. Analysis is presented for both binary and M-ary data modulations. The cumulative distribution function (c.d.f.) of the MUI is utilized in obtaining upper and lower bounds on the p.b.e. Numerical results presented for binary DPSK and FSK signalings show that complex sequences can outperform binary sequences in noncoherent modulation schemes. Acquisition performances of DS/SSMA systems is obtained in the presence of MUI. Two serial search acquisition schemes are considered. The first scheme assumes that there is no data in the reference user's signal until acquisition is achieved. The second scheme allows data modulation in the reference user's signal during the acquisition process. A discrete probability density function of the MUI is used in performance evaluations. Numerical results show that complex and binary sequences have comparable acquisition performances.
Ozluturk, Fatih M, "Coherent and noncoherent DS/SSMA communications with complex signature sequences: Error and acquistion performances" (1994). Doctoral Dissertations Available from Proquest. AAI9510515.