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

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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PAPR Reduction and BER Analysis of the OFDM System Using the TR and DCT Transform

톤 예약 기법과 DCT 변환을 이용한 OFDM 시스템의 PAPR 저감과 BER 분석

  • Byeon, Heui-Seop (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Shinn, Byung-Cheol (Dept. of Electronic Engineering and Research Institute of Computer, Information & Communication, Chungbuk National University) ;
  • Ahn, Do-Seob (Broadband Wireless Transmission Research Team, Digital Broadcasting Research Division, ETRI)
  • 변희섭 (충북대학교 전자공학과 및 컴퓨터정보통신연구소) ;
  • 신병철 (충북대학교 전자공학과 및 컴퓨터정보통신연구소) ;
  • 안도섭 (한국전자통신연구원 디지털방송연구단 광대역무선전송연구팀)
  • Published : 2006.10.31
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Abstract

OFDM system is very useful for the high speed communication system. However, OFDM system has a serious problem of high PAPR that results from the so many subcarriers in the same phase. This OFDM signal is distorted through the nonlinear HPA(High Power Amplifier). Tone reservation method is to insert tone signal in several types to reduce the PAPR after iterating this process by changing the tone signal. Also discrete cosine transform(DCT) can reduces the PAPR as multiplying the cosine value to change the angle and mix up with the data. In the paper, the combination of the TR method and DCT method is newly proposed for more effective reduction of the PAPR. Simulation results show that the proposed method outperforms the conventional simple TR method and DCT method with respect to the PAPR reduction and BER performance.

OFDM(Orthogonal Frequency Division Multiplexing) 시스템은 높은 데이터 속도로 인해 고속 통신에 매우 좋은 방식이다. 그러나 OFDM은 멀티캐리어를 이용하기 때문에 동위상의 신호가 합쳐져 높은 PAPR(Peak to Average Power)이 발생하고, 그로 인해 비선형 증폭기를 거치면서 신호가 왜곡되는 문제점이 발생한다. Tone reservation (TR) 기법은 몇 개의 서브 채널에 임의의 tone 신호를 삽입한 후 원 신호와 결합하여 PAPR을 측정하고, 이 신호를 변경 후 다시 같은 과정을 거치면서 최종적으로 최적의 PAPR값을 갖는 tone 신호를 송신 데이터와 함께 보내는 기법이다. 또한, discrete cosine transform(DCT)은 cosine 값을 데이터에 곱해 줌으로써 위상 회전을 통해 PAPR을 저감하는 기법이다. 본 논문에서는 OFDM 시스템의 보다 효과적인 PAPR 저감을 위해 TR(Tone Reservation)과 DCT 변환 기법을 사용하였다. 그 두 가지 기법을 이용하여 시뮬레이션 비교, 분석 결과 TR 기법에 DCT를 첨가하였을 경우, PAPR 저감 성능이 각각의 성능에 비해 개선되고 또한 $10^{-5}$에서 BER 성능이 TR 기법보다 1 dB, DCT 변환보다 2 dB 정도 향상되는 것을 확인하였다.

Keywords

References

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