DOI QR코드

DOI QR Code

Performance Analysis of Spread Spectrum Underwater Communication Method Based on Multiband

다중 밴드 기반 대역 확산 수중통신 기법 성능분석

  • Received : 2020.09.23
  • Accepted : 2020.10.08
  • Published : 2020.10.30

Abstract

Covertness and performance are very important design goals in the underwater communications. To satisfy both of them, we proposed efficient underwater communication model which combined multiband and direct sequence spread spectrum method in order to improve performance and covertness simultaneously. Turbo coding method with 1/3 coding rates is used for channel coding algorithm, and turbo equalization method which iterately exchange probabilistic information between equalizer and decoder is used for receiver side. After optimal threshold value was set in Rake processing, this paper analyzed the performance by varying the number of chips were 8, 16, 32 and the number of bands were from 1 to 4. Through the simulation results, we confirmed that the performance improvement was obtained by increasing the number of bands and chips. 2~3 dB of performance gain was obtained when the number of chips were increased in same number of bands.

수중음향통신의 적용을 위해 고려되어야 할 두 가지 지표인 성능과 은밀성 관점에서 다중 밴드 통신 기법 및 직접 확산 변조 방식을 적용한 효율적인 통신 모델을 설정하고 성능 분석을 하였다. 최적의 모델에 대한 성능 분석을 위해 송수신기의 채널 부호화 알고리즘을 부호화 비트 수 336 bit를 가지는 부호화율 1/3인 turbo pi 부호화기를 적용하여 등화기와 채널 복호화기를 반복하여 성능을 향상시키는 터보 등화 구조를 제시하였다. 본 논문에서는 다중 밴드 기반 대역 확산 구조의 Rake 처리 과정에서 임계값을 설정하여, 대역 확산 신호의 chip 수를 8개, 16개, 32개로, 다중 밴드 수는 1개에서 4개로 변경하면서 성능을 분석하였다. 시뮬레이션 결과 밴드 수 및 chip 수가 증가함에 따른 성능 이득을 확인할 수 있었으며, 동일한 밴드 수에서 chip 수를 증가시켰을 때 2~3dB 정도 성능이 향상되었다.

Keywords

References

  1. J. Ling, H. He, J. Li, W. Roberts and P. Stoica, "Covert underwater acoustic communications : transceiver structures, waveform designs and associated performances", in Proc. MTS/IEEE OCEANS conference, pp.1-10, 2010.
  2. E. M. Sozer, J. G. Proakis, M. Stojanovic, J. A. Rice, A. Benson and M. Hatch, "Direct Sequence Spread Spectrum Based Modem for Under Water Acoustic Communication and Channel Measurements", IEEE, Oceans'99 MTS, vol. 1, pp. 228-233, Sep, 1999.
  3. J. Ling, et al. "Covert underwater acoustic communications", J. Acoust. Soc. Amer, vol.128, pp.2898-2909, 2010. https://doi.org/10.1121/1.3493454
  4. T. C. Yang and W. B. Yang, "Low signal-to-noise-ratio underwater acoustic communication using direct-sequence spread spectrum signals", IEEE Oceans 2007, pp. 821-826, Jun, 2007.
  5. Karim Ouertani, Samir Saoudi, Mahmoud Ammar and Sebastien Houcke, "Performance comparison of RAKE and SIC/RAKE receivers for multiuser underwater acoustic communication applications", IEEE OCEANS 2007-Europe, pp.1-6, Jun, 2007.
  6. T. C. Yang and W. B. Yang, "Low probability of detection underwater acoustic communication using direct-sequence spread spectrum", Journal of the Acoustical Society of America, vol. 124, pp. 3632-3647, Dec, 2008. https://doi.org/10.1121/1.2996329
  7. Hui-Su Lee, Chang-Uk Baek, Dae-Won Do, Ji-Won Jung, "Performance Analysis of Multiband Transmission Technique in Underwater Acoustic Communication", Journal of Korea Institute of Information, Electronics, and Communication Technology, vol. 11, no.3, pp.253-258, 2018. https://doi.org/10.17661/JKIIECT.2018.11.3.253
  8. C. Douillard and C. Berrou, "Turbo Code with Rate-m/(m+1) Constituent Convolutional Codes", IEEE Trans. Communications, vol. 53, no. 10, pp. 1630-1638, Oct, 2005. https://doi.org/10.1109/TCOMM.2005.857165
  9. L. R. Bahl, J. Cocke, F. Jelinek, and J. Raviv, "Optimal Decoding of Linear Codes for minimizing symbol error rate," IEEE Trans. Inform. Theory, vol. IT-20, no. 2, pp. 284-287, Mar, 1974.
  10. J. Salz, "Optimum mean-square decision feedback equalization", Bell System Technical Journal, vol. 52, no. 8, pp. 1341-1373, Oct, 1973. https://doi.org/10.1002/j.1538-7305.1973.tb02023.x
  11. Ji Won Jung, Ki Man Kim, "Optimizing of iterative turbo equalization for underwater sensor communication", International Journal of Distributed Sensor Network, pp.1-5, Dec, 2013.