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Iterative Decoding and Sparse Channel Estimation for an Underwater Acoustic Telemetry Modem

ITC/USA 2007 Conference Proceedings / The Forty-Third Annual International Telemetering Conference and Technical Exhibition / October 22-25, 2007 / Riviera Hotel & Convention Center, Las Vegas, Nevada / An acoustic modem employing direct-sequence spread-spectrum (DSSS) signaling is considered with LDPC coding. The underwater acoustic channel is tracked using a Kalman filter
which requires accurate data decisions. To improve KF performance and reduce the overall
error rate, joint iterative LDPC decoding and channel estimation is proposed based on a factor graph and sum-product algorithm approximation. In this scheme, the decoder posterior
log likelihood ratios (LLRs) provide data decisions for the KF. Decoder extrinsic LLRs are
similarly incorporated into the detector LLRs to yield improved priors for decoding. Error
rate simulations of the overall modem are provided for a shallow-water channel model with
Ricean/Rayleigh fading.

Identiferoai:union.ndltd.org:arizona.edu/oai:arizona.openrepository.com:10150/604470
Date10 1900
CreatorsIltis, Ronald A.
ContributorsUniversity of California
PublisherInternational Foundation for Telemetering
Source SetsUniversity of Arizona
Languageen_US
Detected LanguageEnglish
Typetext, Proceedings
RightsCopyright © held by the author; distribution rights International Foundation for Telemetering
Relationhttp://www.telemetry.org/

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