Accession Number : ADA306010

Title :   Towards Internet Protocol over Seawater (IP/SW): Forward Error Correction (FEC) Using Hamming Codes for Reliable Acoustic Telemetry.

Descriptive Note : Master's thesis,

Corporate Author : NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s) : Reimers, Stephen P.

PDF Url : ADA306010

Report Date : SEP 1995

Pagination or Media Count : 180

Abstract : Acoustic shallow-water data communications are unreliable. Repeated retransmission of a message received incorrectly often results in transmitter failure due to battery depletion. Internet connectivity to underwater entities via current network protocols does not exist, since most research in data communications has been focused on the physical layer and the underwater channel itself. Therefore, the problems addressed by this thesis are to find a way to increase the reliability of underwater data communications, as well as to specify the steps which need to be taken to enable Internet Protocol (IP) packets to be transmitted over an underwater channel. The approach taken was to add a Hamming forward error-detection and error-correction code to messages, thereby reducing the need for retransmission. This code was implemented in a PC-based communications system which uses commercially available diver's communication and navigation devices as acoustic modems. In a related effort, the internet Protocol stack was analyzed for areas which required modification to enable IP to be reliably passed over an acoustic channel. The results are a low-cost reliable underwater data communications system which can easily be implemented in an AUV or underwater sensor, as well as recommendations for improved protocols required to realize true network communications in an underwater environment. (AN)

Descriptors :   *INTERNET, *TELEMETER SYSTEMS, *ACOUSTIC COMMUNICATIONS, *UNDERWATER COMMUNICATIONS, ALGORITHMS, COMPUTERIZED SIMULATION, OPTIMIZATION, UNDERWATER VEHICLES, DATA PROCESSING SECURITY, COMPUTER COMMUNICATIONS, LOCAL AREA NETWORKS, LOW COSTS, SIGNAL TO NOISE RATIO, THESES, RELIABILITY, COMMUNICATIONS NETWORKS, DATA COMPRESSION, TELEMETERING DATA, DATA LINKS, DIGITAL COMMUNICATIONS, MESSAGE PROCESSING, UNDERWATER ACOUSTICS, SEA WATER, ACOUSTIC DATA, ERROR CORRECTION CODES, DECODING, ERROR DETECTION CODES, PACKET SWITCHING, TELEMETERING TRANSMITTERS, ACOUSTIC CHANNELS.

Subject Categories : Computer Systems
      Telemetry
      Radio Communications
      Acoustics

Distribution Statement : APPROVED FOR PUBLIC RELEASE