Global ETD Search

1	Performance of acoustic spread-spectrum signaling in simulated ocean channels Pelekanos, Georgios N. 06 1900 (has links) Approved for public release, distribution is unlimited / Direct-Sequence Spread Spectrum (DSSS) modulation is being advanced as the physical-layer basis for Seaweb undersea acoustic networking. DSSS meets the need for channel tolerance, transmission security, and multi-user access. This thesis investigates the performance of subspace-decomposition blind-equalization algorithms as alternatives to RAKE processing of DSSS signals. This approach is tailored for superior performance in time-dispersive and frequency-dispersive channels characteristic of ocean acoustic propagation. Transmitter and receiver structures are implemented in Matlab and evaluated with a statistics-based model of a doubly spread channel with additive noise. Receiver performance is examined using Monte Carlo simulation. Biterror rates versus signal-to-noise ratio are presented for various multipath assumptions, noise assumptions, and receiver synchronization assumptions. / Lieutenant, Hellenic Navy Underwater acoustics Acoustic communications Underwater communications Underwater networks Undersea warfare Statistics-based channel modeling Direct-sequence spread spectrum Blind equalization Suspace composition DSSS DSCDMA Telesonar Seaweb