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Performance of Carrier Frequency Offset Compensation using CAZAC Code in Time and Spatial Variant Underwater Acoustic Channel

시·공간 변동 수중음향 채널에서 CAZAC 코드를 적용한 반송파 주파수 옵셋 보상 기법의 성능평가

  • Park, Jihyun (Department of Information and Communication Engineering, Pukyong National University) ;
  • Bae, Minja (Department of Information and Communication Engineering, Pukyong National University) ;
  • Kim, Jongju (Department of Information and Communication Engineering, Pukyong National University) ;
  • Yoon, Jong Rak (Department of Information and Communication Engineering, Pukyong National University)
  • Received : 2016.06.01
  • Accepted : 2016.06.13
  • Published : 2016.07.31

Abstract

In underwater acoustic multipath channel, a performance of underwater acoustic (UWA) communication systems is affected by dynamic variation of boundary and high temporal and spatial variability of the channel conditions. Time and spatial variations of UWA channel induce a carrier frequency offset (CFO) since a phase and a frequency of received signal mismatch with a transmitting signal. Therefore, a performance of a phase shift keying underwater acoustic communication system is degraded. In this study, we have analyzed a performance of CFO estimation and compensation using a phase code in time and spatial variation channel. A constant amplitude zero autocorrelation (CAZAC) signal is applied as a phase code signal and its performance is evaluated in water tank. The bit error rate of a quadrature phase shift keying (QPSK) system with a phase code is improved about 4 to 10 times better than that without a phase code.

수중 음향 다중경로 채널에서 수중음향 통신 시스템의 성능은 채널의 시변적 경계면 상태 변동에 의해 영향을 받는다. 이러한 채널에서 시공간적 변동에 의해 송신 신호와 수신 신호의 위상과 주파수가 일치하지 않아 반송 주파수 옵셋이 발생되고 위상편이키잉 방식의 수중음향통신시스템의 성능을 저하시킨다. 본 논문에서는 수중 음향 통신 채널의 시 공간적 변동 채널에서 위상 코드를 적용한 반송 주파수 옵셋 보상 추정 기법의 성능을 평가하였다. 위상 코드는 주파수 옵셋을 추정하고 보상하기 위한 코드로 CAZAC를 적용하였으며, 실내 수조에서 성능을 평가하였다. QPSK 시스템에 위상코드를 적용한 결과는 적용하지 않은 경우보다 약 4-6배 비트오류율이 개선되었다.

Keywords

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