The Optimal Turbo Coded V-BLAST Technique in the Adaptive Modulation System corresponding to each MIMO Scheme

적응 변조 시스템에서 각 MIMO 기법에 따른 최적의 터보 부호화된 V-BLAST 기법

  • Lee, Kyung-Hwan (Dept. of Electronics & Computer Eng. Chonnam National University) ;
  • Ryoo, Sang-Jin (Dept. of Electronics & Computer Eng. Chonnam National University) ;
  • Choi, Kwang-Wook (Dept. of Electronics & Computer Eng. Chonnam National University) ;
  • You, Cheol-Woo (Dept. of Communication Eng. Myongji University) ;
  • Hong, Dae-Ki (Dept. of I & T Eng. Sangmyoung University) ;
  • Kim, Dae-Jin (Dept. of Electronics & Computer Eng. Chonnam National University) ;
  • Hwang, In-Tae (Dept. of Electronics & Computer Eng. Chonnam National University) ;
  • Kim, Cheol-Sung (Dept. of Electronics & Computer Eng. Chonnam National University)
  • 이경환 (전남대학교 전자컴퓨터공학과) ;
  • 류상진 (전남대학교 전자컴퓨터공학과) ;
  • 최광욱 (전남대학교 전자컴퓨터공학과) ;
  • 유철우 (명지대학교 통신공학과) ;
  • 홍대기 (상명대학교 정보통신공학과) ;
  • 김대진 (전남대학교 전자컴퓨터공학과) ;
  • 황인태 (전남대학교 전자컴퓨터공학과) ;
  • 김철성 (전남대학교 전자컴퓨터공학과)
  • Published : 2007.06.25

Abstract

In this paper, we propose and analyze the Adaptive Modulation System with optimal Turbo Coded V-BLAST(Vertical-Bell-lab Layered Space-Time) technique that adopts the extrinsic information from MAP (Maximum A Posteriori) Decoder with Iterative Decoding as a priori probability in two decoding procedures of V-BLAST; the ordering and the slicing. Also, we consider and compare the Adaptive Modulation System using conventional Turbo Coded V-BLAST technique that is simply combined V-BLAST with Turbo Coding scheme and the Adaptive Modulation System using conventional Turbo Coded V-BLAST technique that is decoded by the ML (Maximum Likelihood) decoding algorithm. We observe a throughput performance and a complexity. As a result of a performance comparison of each system, it has been proved that the complexity of the proposed decoding algorithm is lower than that of the ML decoding algorithm but is higher than that of the conventional V-BLAST decoding algorithm. however, we can see that the proposed system achieves a better throughput performance than the conventional system in the whole SNR (Signal to Noise Ratio) range. And the result shows that the proposed system achieves a throughput performance close to the ML decoded system. Specifically, a simulation shows that the maximum throughput improvement in each MIMO scheme is respectively about 350 kbps, 460 kbps, and 740 kbps compared to the conventional system. It is suggested that the effect of the proposed decoding algorithm accordingly gets higher as the number of system antenna increases.

본 논문에서는 V-BLAST (Vertical-Bell-lab Layered Space Time) 복호 알고리즘의 ordering과 slicing 과정에 MAP(Maximum A Posteriori) 디코더의 외부 정보 (extrinsic information)를 이용한 최적의 터보 부호화된 (Optimal Turbo Coded) V-BLAST 적응 변조 시스템을 제안 후 성능을 관찰한다. 또한, 적응 변조 시스템에서 간단하게 V-BLAST 시스템과 터보 부호화 (Turbo Coding) 기법이 결합된 기존의 터보 부호화된 V-BLAST 기법을 적용한 경우와 기존의 터보 부호화된 V-BLAST 기법에서 V-BLAST 디코딩 알고리즘 대신 ML (Maximum Likelihood) 디코딩 알고리즘을 적용한 경우에 비교하여 전송률 (throughput) 성능과 복잡도를 살펴본다. 게다가, MIMO (Multiput-Input-Multiple-Output) 기법을 적용하여 제안된 시스템의 성능 개선을 확인한다. 모의 실험 결과, 제안된 디코딩 알고리즘은 ML 디코딩 알고리즘에 비해 복잡도가 낮으나, 기존의 시스템에 비해 복잡도가 높다. 하지만, 성능 개선 측면에서 제안된 시스템의 전송률 성능은 기존의 시스템에 비하여 전신호 대 잡음 비(SNR: Signal to Noise Ratio) 구간에서 우수하고, ML 디코딩 알고리즘을 적용한 기존 시스템의 전송률 성능에 거의 근접함을 보인다. 특히, 실험 결과는 각 MIMO 기법에서 제안된 시스템이 기존의 시스템에 비하여 각각 최대 350kbps, 460 kbps, 740 kbps의 전송률 성능 개선을 보여주고, 이것은 제안된 디코딩 알고리즘의 효과가 송 수신안테나의 수가 증가할수록 커진다는 것을 의미한다.

Keywords

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