Global ETD Search

1	Link-layer and network-layer performance of an undersea acoustic network at Fleet Battle Experiment-India Hartfield, Grant I. 06 1900 (has links) Approved for public release, distribution is unlimited / This thesis is an analysis of the link-layer and network-layer performance of an experimental Seaweb undersea acoustic network. The objective is to statistically determine RTS/CTS handshaking and ARQ retransmission performance during the Fleet Battle Experiment-India, executed in June 2001. Many factors constrain or impair undersea acoustic communications. Analysis of a sample portion of the data reveals insights about the overall throughput, latency, and reliability of the Seaweb network. / Lieutenant, United States Navy Underwater acoustics Link layer Network layer Undersea acoustics Seaweb
2	A discovery process for initializing ad hoc underwater acoustic networks Ong, Chee Wei. January 2008 (has links) (PDF) Thesis (M.S. in Engineering Acoustics)--Naval Postgraduate School, December 2008. / Thesis Advisor(s): Rice, Joseph A. "December 2008." Description based on title screen as viewed on January 29, 2009. Includes bibliographical references (p. 89-91). Also available in print.
3	A selective automatic repeat request protocol for undersea acoustic links Kalscheuer, Jon M. 06 1900 (has links) Approved for public release, distribution is unlimited / A recent improvement to the Seaweb underwater wireless network was the implementation of a Selective Automatic Repeat Request (SRQ) mechanism. SRQ is a protocol implemented in the Seaweb link layer as a measure for mitigating unreliability inherent in the telesonar physical layer. In January 2004, an experiment was performed in St. Andrew's Bay, Panama City, Florida. The goal was to transmit large data files through the network, in accordance with a Naval Special Warfare need for imagery file telemetry. For three point-to-point test geometries, SRQ was tested with a noisy and variable physical layer. Through the incorporation of SRQ, the unreliability was overcome. A link-budget model calibrated with the sound channel data collected from the experiment establishes the benefit of a "SRQ gain." / Ensign, United States Navy Underwater acoustics Underwater acoustic telemetry SRQ Link-budget Acoustic communications FORCEnet Link layer Telemetry ARQ Telesonar Seaweb
4	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

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