The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
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Analysis of underwater acoustic communication channel environment in Kyungcheon Lake

경천호에서의 수중 음향 통신 채널 환경 분석

  • Received : 2018.10.17
  • Accepted : 2019.01.25
  • Published : 2019.01.31
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Abstract

This paper estimated communication parameters according to underwater channel environment of lake for underwater acoustic communication. This paper calculated coherence time and coherence bandwidth through two experiments in actual lake environments. In both experiments, the chirp signal for channel estimation and the BPSK (Binary Phase Shift Keying) signal for calculating the bit error rate were transmitted. In each experiment, the distance between transmitter and receiver was 300 m to 400 m, and 500 m to 600 m. The coherence times calculated in experiment 1 and experiment 2 are 175 msec and 340 msec, and the coherence bandwidths are 10 Hz and 5.71 Hz, respectively. It is confirmed that the experimental results are more appropriate because the synchronization and the bit error rate performance are better only when the length of the synchronization signal and the interval of the pilot signal in the frame are shorter than the coherence time.

본 논문은 호수에서의 원활한 수중음향통신을 위해 호수의 수중 채널 환경에 따른 통신 변수들을 도출하였다. 본 논문에서는 실제 호수 환경에서의 두 번의 실험을 통하여 상관 시간과 상관 대역폭을 산출하였다. 두 번의 실험에서 채널 추정과 비트오류율 산출을 위해 chirp 신호와 BPSK(Binary Phase Shift Keying) 신호를 전송하였고, 각각의 실험은 송신단과 수신단과의 거리가 300 m에서 400 m일 때와 500 m에서 600 m일 때 진행하였다. 첫 번째 실험과 두 번째 실험에서 각각 산출한 상관 시간은 175 msec와 340 msec이고, 상관 대역폭은 10 Hz와 5.71 Hz이다. 동기 신호의 길이와 프레임 내 파일럿 신호의 간격이 상관 시간보다 짧은 경우에만 동기화와 비트오류율 성능이 더 우수하여 산출한 실험 결과가 적절함을 확인하였다.

Keywords

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Fig. 1. Doppler channel and Tx/Rx movement environ-ment.

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Fig. 2. Example of an underwater channel response.

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Fig. 3. Mimetic diagram for experiment in Kyungcheon Lake.

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Fig. 4. Kyungcheon Lake topography and direction of experiment.

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Fig. 5. Underwater channel response of Kyungchun Lake in experiment 1.

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Fig. 6. Underwater channel response of Kyungchun Lake in experiment 2.

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Fig. 7. RMS delay spread according to distance change.

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Fig. 8. Synchronization results from T0 ≥TS in experiment 1.

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Fig. 9. Synchronization results from T0 < TS in experiment 1.

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Fig. 10. Synchronization results from T0 ≥TS in experiment 2.

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Fig. 11. Synchronization results from T0 < TS in experiment 2.

Table 1. Experiment parameter.

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Table 2. Maximum Doppler frequency and coherence time according to experiment.

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Table 3. RMS delay spread and coherence bandwidth according to experiment.

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Table 4. Pilot interval in frame and bit error rate in experiment 1.

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Table 5. Pilot interval in frame and bit error rate in experiment 2.

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