Noncoherent Hybrid DS-SFH Spread-Spectrum Multiple-Access Communications.
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The performance of noncoherent reception in synchronous hybrid direct-sequence/slow-frequency-hopped spread-spectrum multiple- access communication systems operating through additive white Gaussian noise channels is investigated. Systems with binary and Mary frequency-shift-keying modulation and noncoherent demodulation, as well as systems with differential-phase-shift keying modulation and differentially coherent demodulation are examined and their probability of error is evaluated for random frequency-hopping patterns and signature sequences. The multiple-access capability of noncoherent hybrid spread- spectrum is shown to be superior to that of noncoherent purely frequency-hopped spread-spectrum , interior to that of noncoherent purely direct-sequence spread-spectrum for systems with the same bandwidth expansion. Comparison for hybrid systems with coherent , noncoherent demodulation shows a considerable loss in the performance of the noncoherent systems.