The Journal of Korean Institute of Electromagnetic Engineering and Science (한국전자파학회논문지)

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Performance Analysis of a OFDM System for Wireless LAN in Indoor Wireless Channel

실내 무선 채널 환경에서 무선 LAN용 OFDM 시스템의 성능 분석

  • Choi, Yeoun-Joo (Department of Computer & Communication Engineering in Chungbuk National Univ.) ;
  • Kim, Hang-Rae (Department of Computer & Communication Engineering in Chungbuk National Univ.) ;
  • Kim, Nam (Department of Computer & Communication Engineering in Chungbuk National Univ.) ;
  • Ko, Young-Hoon (Department of Computer Engineering in HyupSung Univ.) ;
  • Ahn, Jae-Hyeong (Department of Computer & Communication Engineering in Chungbuk National Univ.)
  • 최연주 (충북대학교 정보통신공학과) ;
  • 김항래 (충북대학교 정보통신공학과) ;
  • 김남 (충북대학교 정보통신공학과) ;
  • 고영훈 (협성대학교 컴퓨터공학과) ;
  • 안재형 (충북대학교 정보통신공학과)
  • Published : 2001.02.01
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Abstract

In this paper, the system performance with the convolution code using a Viterbi decoding and the one tap LMS equalizer applied to the OFDM system, which is suitable for IEEE 802.1la wireless LAN in indoor wireless channel, is analyzed through computer simulation. Indoor wireless channel is modeled as Rician fading channel, and QPSK and 16QAM scheme are used for subchannel modulation. In Rician fading channel with the power ratio of the direct path signal to the scattered signals, K=5 dB, BER of $10^{-4}$ is satisfied if the SNRs of the QPSK/OFDM and the 16QAM/OFDM are 8.6 dB and 19.2 dB in hard decision and 5.3 dB and 9.8 dB in soft decision, respectively. Compared with convolution code scheme, it is observed that 16QAM/OFDM system with the one tap LMS equalizer has the performance improvement of 8.6 dB and 2 dB in hard decision and soft decision, respectively.

본 논문에서는 IEEE 802.11a 무선 LAN에 적합한 OFDM 시스템에 비터비 복호를 사용하는 길쌈 부호와 단일 탭의 LMS 등화기를 적용하여 실내 무선 채널 환경에서 시스템 성능을 시뮬레이션을 통해 분석한다. 실내 무선 채널은 라이시안 페이딩 모델링하고, 부채널변조 방식으로는 QPSK와 16QAM을 사용한다. 직접 파 대 간섭파 전력비 K=5 dB 인 라이시안 페이딩 채널에서 길쌈 부호 및 비터비 복호를 사용하는 경우, 경판정에서 QPSK는 8.6 dB, 16QAM 은 19.2dB, 연판정에서 QPSK는 5.3dB, 16QPSK는 5.3dB, 16QAM은 9.8dB에서 $10^{-4}$의 BER을 만족하였다. 또한 16QAM/OEFM 방식에 단일 탭의 LMS 등화기를 사용하면 길쌈 부호만을 사용한 경우보다 경판정 비터비 복호의 경우 8.6dB,연판정의 경우에는 2dB의 성능이 향상됨을 알 수 있었다.

Keywords

References

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