The Journal of the Acoustical Society of Korea (한국음향학회지)

The Acoustical Society of Korea (한국음향학회)
권호 표지

The Experimental Verification of Adaptive Equalizers with Phase Estimator in the East Sea

동해 연근해에서 위상 추정기를 갖는 적응형 등화기의 실험적 성능 검증

  • Received : 2010.02.24
  • Accepted : 2010.05.11
  • Published : 2010.05.31
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Abstract

Phase coherent modulation techniques in underwater acoustic channel can improve bandwidth efficiency and data reliability, but they are made difficult by time-varying intersymbol interference. This paper proposes an adaptive equalizer combined with phase estimator which compensates distortions caused by time-varying multipath and phase variation. The experiment in the East sea demonstrates phase coherent signals are distorted by time-varying multipath propagation and the proposed scheme equalizes them. Bit error rate of BPSK and QPSK are 0.0078 and 0.0376 at 300 meter horizontal distance and 0.0146 and 0.0293 at 1000 meter respectively.

위상동기식 변조기법은 주파수 대역폭의 효율과 전송 신뢰도를 높일 수 있으나 수중 채널의 시변 다중경로에 의해 인접 심볼간 간섭이 발생되어 수중통신에 적용하는 데 어려움이 있다. 본 논문에서는 동해 연근해에서 위상동기 변조방식인 BPSK와 QPSK 신호를 전송하고, 시간에 따라 변화하는 다중경로와 위상변동에 의해 왜곡된 수신신호를 보상하기 위한 위상 추정기를 결합한 적응형 등화기를 제안한다. 해상실험을 통해 전송된 위상동기식 변조신호가 수중채널의 시변 다중경로 특성에 의해 왜곡되었음을 보였고 제안된 방법에 의해 왜곡된 신호가 보정됨을 보였다. BPSK와 QPSK 신호 전송시 300 m 거리에서 각각 0.0078, 0.0376의 비트 오류율을 보였으며, 1000 m 거리에서는 0.0146, 0.0293의 비트 오류율을 보였다.

Keywords

References

  1. M. Stojanovic, J. Catipovic, and J. Proakis, "Phase-coherent digital communications for underwater acoustic channels," IEEE J. OCEAN. ENG, vol. 19, no. 1, pp. 100-111, Sep. 1994. https://doi.org/10.1109/48.289455
  2. M. Stojanovic, "Recent advances in high-speed underwater acoustic communications," IEEE J. OCEAN. ENG., vol. 21, no. 2, pp. 125-136, Apr. 1996. https://doi.org/10.1109/48.486787
  3. D. Kilfoyle and A. Baggeroer, "The state of the art in underwater acoustic telemetry," IEEE J. OCEAN. ENG., vol. 25, no. 1, pp. 4-27, Jan. 2000. https://doi.org/10.1109/48.820733
  4. 김현수, 권양수, 이일신, 정재학, 김성일, "시역전 수중 디지털 통신 성능 분석," 한국음향학회지, 28권, 3호, 213-221쪽, 2009.
  5. R. Urick, Priciples of underwater sound, McGraw-Hill, pp. 99-201, 1983.
  6. A. Goldsmith, Wireless communications, Cambridge university press, pp. 159-183, 2005
  7. J. Catipovic, "Performance limitations in underwater acoustic telemetry," IEEE J. OCEAN. ENG., vol. 15, no. 3, pp. 205-216, Jul. 1990. https://doi.org/10.1109/48.107149
  8. J. Proakis, "Adaptive equalization techniques for acoustic telemetry channels," IEEE J. OCEAN. ENG., vol. 16, no. 1, pp. 21-31, Jan. 1991. https://doi.org/10.1109/48.64882
  9. G. Howe, P. Tarbit, O. Hinton, B. Sharif and A. Adams, "Sub-sea acoustic remote communications utilising an adaptive receiving beamformer for multipath suppression," in Proc. OCEANS '94. vol. 1, pp. 313-316, Sep. 1994.
  10. J. Flynn, J. Ritcey, D. Rouseff and W. Fox, "Multichannel equalization by decision-directed passive phase conjugation: Experimental results," IEEE J. OCEAN. ENG., vol. 29, no. 3, pp. 824-836, Jul. 2004 https://doi.org/10.1109/JOE.2004.831618
  11. H. Song, W. Hodgkiss, W. Kuperman, M. Stevenson and T. Akal, "Improvement of time-reversal communications using adaptive channel equlizers," IEEE J. OCEAN. ENG., vol. 31, no. 2, pp. 487-496, Apr. 2006 https://doi.org/10.1109/JOE.2006.876139
  12. B. Sklar, Digital communications : Fundamental and Applications, Prentice-Hall Int., pp. 149-157, 2001.
  13. J. Beek, O. Edfors, M. Sandell, "On channel estimation in OFDM systems," in Proc. of Veh. Tech. Conf., vol. 2, pp.815-819, Sep. 1995.
  14. S. Haykin, Adaptive filter theory 3rd ed., Prentice-Hall Int., pp. 365-438, 1996.
  15. D. Falconer, "Jointly adaptive equalization and carrier recovery in two dimensional digital communication systems," Bell Syst. Tech. J., vol. 55, pp. 317-334, Mar. 1976. https://doi.org/10.1002/j.1538-7305.1976.tb03317.x
  16. J. Proakis, Digital communications 5th ed., McGraw-Hill., pp. 303-308, 2008.