한국해양대학교

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수중음향통신에서 주파수 평균 및 재귀프레임 방식을 이용한 도플러 추정

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dc.contributor.author 황찬호 -
dc.date.accessioned 2017-02-22T06:26:07Z -
dc.date.available 2017-02-22T06:26:07Z -
dc.date.issued 2015 -
dc.date.submitted 57071-01-11 -
dc.identifier.uri http://kmou.dcollection.net/jsp/common/DcLoOrgPer.jsp?sItemId=000002175340 ko_KR
dc.identifier.uri http://repository.kmou.ac.kr/handle/2014.oak/9533 -
dc.description.abstract In recent years, underwater sensor networks can be used for environment monitoring, disaster prevention, and military surveillance. Unlike terrestrial communication, underwater acoustic communication utilizes sound waves. The sound speed is dependent on the water temperature and the salinity. The sound transmission path is changed by refraction according to the gradient of vertical sound velocity. When sound waves are passed through the underwater, they are affected by attenuation, reflection of bottom and surface, scattering, ambient noise, and the Doppler effect caused by movement of the transmitter and the receiver. Of these factors, the Doppler effect affects the correlation time of the channel related to the transmission efficiency. These influences thus cannot be neglected in the design of underwater acoustic communication systems. To increase transmission efficiency, estimation the changing Doppler frequency and compensation for distortion are needed. In this thesis, Doppler shift frequency estimation methods to use in the time varying channel proposed. Two kinds of methods are proposed. One is a Doppler estimation algorithm that has stable performance as a part of the communication system. From an overall communication system perspective, the other is a demodulation scheme that is different from the conventional communication system. The ambiguity function and decision-directed estimation are presented. Also, a more accurate Doppler estimation method that is based on decision-directed estimation is proposed, and a re-modulation method that can update the channel parameters for the equalizer operation and estimate the Doppler frequency during the data frame using two Doppler estimation techniques is proposed. A simulation based on the Bellhop modeling and sea experiment was carried out to compare the performance of the proposed method with a conventional non-recursive Doppler estimation. When the channel coding technique was not applied, the uncoded bit error rate performance of the proposed method was improved about maximum 50.3 % compared with conventional method. -
dc.description.tableofcontents List of Tables iii List of Figures iv Abstract v 제 1 장 서론 1 제 2 장 수중음향 채널 4 2.1 수중음향 채널의 특성 4 2.1.1 전달 손실 5 2.1.2 다중 경로 전달 6 2.1.3 도플러 효과 7 2.1.4 잡음 8 2.2 수중음향 채널의 시변동성 8 2.2.1 시간영역 상관도 9 2.2.2 도플러 효과의 영향 12 제 3 장 도플러 추정을 위한 기법 14 3.1 기존의 도플러 추정 방법 14 3.1.1 모호 함수 기법 14 3.1.2 Decision-directed 추정 기법 16 3.2 제안된 도플러 추정 방법 17 3.2.1 주파수 평균 기반의 Decision-directed 추정 기법 18 3.2.2 재귀 프레임 변복조 19 제 4 장 모의실험 및 실험 결과 분석 23 4.1 모의실험 결과 23 4.2 호수실험 결과 26 4.3 해상실험 결과 29 제 5 장 결론 33 참고문헌 35 감사의 글 38 -
dc.language kor -
dc.publisher 한국해양대학교 대학원 -
dc.title 수중음향통신에서 주파수 평균 및 재귀프레임 방식을 이용한 도플러 추정 -
dc.title.alternative Doppler estimation based on frequency average and recursive frame method for underwater acoustic communication -
dc.type Thesis -
dc.date.awarded 2015-08 -
dc.contributor.alternativeName Chan Ho Hwang -
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전파공학과 > Thesis
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