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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Low Density Parity Check (LDPC) Coded OFDM System Using Unitary Matrix Modulation (UMM)

UMM(Unitary Matrix Modulation)을 이용한 LDPC(Low Density Parity Check) 코디드 OFDM 시스템

  • 김남수 (모빌링크 텔레콤(주)) ;
  • 강환만 (삼성전자 정보통신총괄 통신연구소) ;
  • 조성호 (한양대학교 정보통신대학)
  • Published : 2005.05.01
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Abstract

Unitary matrix modulation (UMM) is investigated in multiple antennas system that is called unitary space-time modulation (USTM). In an OFDM, the diagonal components of UMM with splitting over the coherence bandwidth (UMM-S/OFDM) have been proposed. Recently LDPC code is strongly attended and studied due to simple decoding property with good error correction property. In this paper, we propose LDPC coded UMM-S/OFDM for increasing the system performance. Our proposed system can obtain frequency diversity using UMM-S/OFDM like USTM/OFDM, and large coding gain using LDPC code. The superior characteristics of the proposed UMM-S/OFDM are demonstrated by extensive computer simulations in multi-path Rayleigh fading channel.

다중 안테나 시스템에서 UMM (unitary matrix modulation)을 사용한 방법을 USTM (unitary space-time modulation)이라 부른다. OFDM 시스템에서 coherence bandwidth 만큼의 이격을 두고 UMM의 대각 행렬을 이용한 방법이 제안되고 있다. 또한 최근에 디코딩 방법이 간단하고 좋은 성능을 갖는 LDPC (low density parity check) 코드에 대한 연구가 진행되고 있다. 본 논문에서 UMM (unitary matrix modulation)을 사용하고 LDPC 코디드 된 OFDM 시스템을 제안한다. 또한 다중 송신 안테나를 사용하여 송신 diversity 이득을 얻는 것이 아니라, 하나의 송신 안테나를 이용하여 채널의 coherence bandwidth 만큼의 주파수 간격 (splitting)을 두어 채널에 대한 주파수 이득을 고려하여 UMM/OFDM 시스템을 설계 하였다. 이 방법을 이용하여 본 논문에서 제안된 UMM-S/OFDM에 대한 성능 특성을 다중 경로 Rayleigh 페이딩 채널 환경에서 시뮬레이션을 통하여 검증하였다.

Keywords

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