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dc.contributor.authorRadosevic, A.en_US
dc.contributor.authorAhmed, R.en_US
dc.contributor.authorDuman, T. M.en_US
dc.contributor.authorProakis, J. G.en_US
dc.contributor.authorStojanovic, M.en_US
dc.date.accessioned2016-02-08T11:02:45Z
dc.date.available2016-02-08T11:02:45Z
dc.date.issued2014en_US
dc.identifier.issn0364-9059
dc.identifier.urihttp://hdl.handle.net/11693/26642
dc.description.abstractIn this paper, we explore design aspects of adaptive modulation based on orthogonal frequency-division multiplexing (OFDM) for underwater acoustic (UWA) communications, and study its performance using real-time at-sea experiments. Our design criterion is to maximize the system throughput under a target average bit error rate (BER). We consider two different schemes based on the level of adaptivity: in the first scheme, only the modulation levels are adjusted while the power is allocated uniformly across the subcarriers, whereas in the second scheme, both the modulation levels and the power are adjusted adaptively. For both schemes we linearly predict the channel one travel time ahead so as to improve the performance in the presence of a long propagation delay. The system design assumes a feedback link from the receiver that is exploited in two forms: one that conveys the modulation alphabet and quantized power levels to be used for each subcarrier, and the other that conveys a quantized estimate of the sparse channel impulse response. The second approach is shown to be advantageous, as it requires significantly fewer feedback bits for the same system throughput. The effectiveness of the proposed adaptive schemes is demonstrated using computer simulations, real channel measurements recorded in shallow water off the western coast of Kauai, HI, USA, in June 2008, and real-time at-sea experiments conducted at the same location in July 2011. We note that this is the first paper that presents adaptive modulation results for UWA links with real-time at-sea experiments.en_US
dc.language.isoEnglishen_US
dc.source.titleIEEE Journal of Oceanic Engineeringen_US
dc.relation.isversionofhttp://dx.doi.org/10.1109/JOE.2013.2253212en_US
dc.subjectAdaptive modulationen_US
dc.subjectFeedbacken_US
dc.subjectOrthogonal frequency-division multiplexing (OFDM)en_US
dc.subjectUnderwater acoustic (UWA) communicationen_US
dc.subjectComputer simulationen_US
dc.subjectExperimentsen_US
dc.subjectFeedbacken_US
dc.subjectOrthogonal frequency division multiplexingen_US
dc.subjectUnderwater acousticsen_US
dc.subjectAt-sea experimenten_US
dc.subjectAverage bit-error ratesen_US
dc.subjectChannel measurementsen_US
dc.subjectDesign considerationsen_US
dc.subjectModulation levelsen_US
dc.subjectPropagation delaysen_US
dc.subjectSparse channel impulse responseen_US
dc.subjectUnderwater acoustic communicationsen_US
dc.subjectAdaptive modulationen_US
dc.titleAdaptive OFDM modulation for underwater acoustic communications: Design considerations and experimental resultsen_US
dc.typeArticleen_US
dc.departmentDepartment of Electrical and Electronics Engineeringen_US
dc.citation.spage357en_US
dc.citation.epage370en_US
dc.citation.volumeNumber39en_US
dc.citation.issueNumber2en_US
dc.identifier.doi10.1109/JOE.2013.2253212en_US
dc.publisherInstitute of Electrical and Electronics Engineers Inc.en_US


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