The Journal of Korean Institute of Communications and Information Sciences (한국통신학회논문지)

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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An Improved Reconstruction Algorithm of Convolutional Codes Based on Channel Error Rate Estimation

채널 오류율 추정에 기반을 둔 길쌈부호의 개선된 재구성 알고리즘

  • Seong, Jinwoo (Hongik University Department of Electronics, Information and Communication Engineering) ;
  • Chung, Habong (Hongik University Department of Electronic and Electrical Engineering)
  • Received : 2017.03.28
  • Accepted : 2017.04.25
  • Published : 2017.05.31
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Abstract

In an attack context, the adversary wants to retrieve the message from the intercepted noisy bit stream without any prior knowledge of the channel codes used. The process of finding out the code parameters such as code length, dimension, and generator, for this purpose, is called the blind recognition of channel codes or the reconstruction of channel codes. In this paper, we suggest an improved algorithm of the blind recovery of rate k/n convolutional encoders in a noisy environment. The suggested algorithm improves the existing algorithm by Marazin, et. al. by evaluating the threshold value through the estimation of the channel error probability of the BSC. By applying the soft decision method by Shaojing, et. al., we considerably enhance the success rate of the channel reconstruction.

채널 재구성 기법이란 통신시스템에서 의도되지 않은 수신자가 수신 신호로부터 어떤 채널 부호가 사용되었는지, 주요 파라미터는 무엇인지를 알아내는 기법이다. 본 논문은 수신한 신호가 길쌈부호로 부호화된 경우, 사용된 길쌈부호의 주요파라미터인 입출력단의 비트수인 k와 n, 그리고 $k{\times}n$ 생성다항식행렬(Polynomial Generator Matrix, PGM)을 찾아내는 기법에 대해 다룬다. 본 논문은 M. Marazin 등이 제안한, 피버팅을 통한 가우스 조단소거법(Gauss Jordan Elimination Through Pivoting, GJETP)을 사용한 길쌈부호의 채널 재구성 기법에서 채널오류율과 무관하게 임계값을 설정해주던 것과 달리, 수신한 시퀀스로부터 2진 대칭 채널(Bynary Symetric Channel, BSC)의 채널오류확률을 추정하고 이로부터 임계값을 설정하는 방식을 제안하고, S. Shaojing 등의 연판정(soft decision) 값을 이용한 기법을 적용시켜서 채널 재구성 기법의 성공률을 향상시켰다.

Keywords

References

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