Journal of the Korea Institute of Information and Communication Engineering (한국정보통신학회논문지)

The Korea Institute of Information and Commucation Engineering (한국정보통신학회)
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Performance of selective combining according to channel selection decision method of frequency diversity in underwater frequency selective channel

수중 주파수 선택적 채널에서 주파수 다이버시티의 채널 선택 판정법에 따른 선택 합성법의 성능

  • Lee, Chaehui (Department of Information and Communication Engineering, Pukyong National University) ;
  • Jeong, Hyunsoo (Department of Information and Communication Engineering, Pukyong National University) ;
  • Park, Kyu-Chil (Department of Information and Communication Engineering, Pukyong National University) ;
  • Park, Jihyun (The Sound Vibration Engineering Research Center, Pukyong National University)
  • Received : 2022.01.21
  • Accepted : 2022.02.19
  • Published : 2022.03.31
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Abstract

In this paper, the performance of the selective combining according to the channel selection decision method of frequency diversity is evaluated in the underwater frequency selective channel. The underwater acoustic channel in the shallow sea has a complex multipath characteristic by combining various environmental factors such as boundary surface reflection and sound wave refraction according to the water temperature layer. In particular, frequency selectivity due to multipath causes energy fluctuation in a communication channel, which reduces SNR (Signal to Noise Ratio) and deteriorates communication performance. In this paper, we applied the frequency diversity technique using multiple channels to secure the communication performance according to the frequency selectivity by multipath. For each channel, 4-FSK (Frequency Shift Keying) and selective combining were applied, the performance was evaluated by applying the maximum value, average value, and majority decision of the signal in order to decide the demodulation channel selection of the selective combining.

본 논문은 수중 주파수 선택적 채널에서 주파수 다이버시티의 채널 선택 판정법에 따른 선택 합성법 (selective combining)의 성능을 평가하였다. 천해 수중 음향 채널은 경계면 반사와 수온 층에 따른 음파 굴절 등의 다양한 환경요인이 결합하여 복잡한 다중경로의 특성을 가진다. 특히, 다중경로에 의한 주파수 선택성 (frequency selectivity)는 통신 채널의 에너지 변동을 발생시키고, 이로 인해 SNR (Signal to Noise Ratio)가 감소하여 통신성능이 저하된다. 본 논문에서는 다중경로의 주파수 선택성에 따른 통신성능 확보를 위해 다수의 채널을 이용하는 주파수 다이버시티 기법을 적용하였다. 각 채널은 4-FSK (Frequency Shift Keying)과 선택 합성법을 적용하였으며, 선택 합성법의 복조 채널 선택 판정을 위해 신호의 최댓값, 평균값 그리고 심벌 비교 판정 (majority decision)을 적용하여 성능을 평가하였다.

Keywords

Acknowledgement

This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (Ministry of Education) NO. NRF-2019R1I1A1A01063575).

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