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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Design and Performance Evaluation of an Advanced CI/OFDM System for the Reduction of PAPR and ICI

PAPR과 ICI의 동시 저감을 위한 개선형 CI/OFDM 시스템 설계와 성능 평가

  • 유흥균 (충북대학교 전기전자컴퓨터공학부)
  • Published : 2008.06.30
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Abstract

OFDM (orthogonal frequency division multiplexing) has serious problem of high PAPR (peak-to-average power ratio). Recently, CI/OFDM (carrier interferometry OFDM) system has been proposed for the low PAPR. However, CI/OFDM system shows another problem of ICI because of phase offset mismatch due to the phase noise. In this paper, to simultaneously reduce the PAPR and ICI effects, we propose an A-CI/OFDM (advanced-CT/OFDM). This method improves the BER performance by use of the margin of phase offset at CI codes. Propose system to reduce the effect the phase noise, even though it shows a little bit higher PAPR than conventional CI/OFDM, so we apply the PTS among the PAPR reduction techniques to proposed system to mitigate this problem. Therefore, it improves the total BER performance because the proposed method can decrease the effect of phase noise and get the gain in PAPR reduction performance. From the simulation results, we can show the performance comparison between the conventional OFDM, CI/OFDM and A-CI/OFDM.

OFDM(orthogonal frequency division multiplexing)은 PAPR(peak-to-average power ratio) 문제를 가지고 있다. 이런 PAPR 문제를 해결하는 CI/OFDM(carrier interferometry OFDM) 시스템 등이 제시되었으나, 이것은 위상 잡음이 존재할 경우 CI 위상 오프셋 불일치로 인해 ICI(inter channel interference) 문제가 발생한다. 이 논문에서는 낮은 PAPR을 유지하면서 ICI를 저감하기 위한 A-CI/OFDM(advanced-CI/OFDM)을 제안한다. 이 방식은 CI 확산 과정에서 CI 위상 코드들이 조밀하게 갖는 위상 옵셋에 마진을 줌으로써 국부 발진기에서 발생하는 위상 잡음에 대한 성능 저하를 감소시키면서, 낮은 PAPR을 유지한다. 위상 잡음에 대한 영향을 줄이기 위해 제안된 방식은 종전의 CI/OFDM보다 PAPR 성능 면에서 손실이 발생하는데, 이를 방지하기 위하여 PAPR 저감 방법 중 PTS를 이 시스템에 적용한다. 그러므로 제안한 방식은 기존의 CI/OFDM 시스템보다 위상 잡음의 영향을 저감하고 PAPR 측면에서도 이득이 있어 전체적인 BER 성능을 향상 시킨다. 시뮬레이션을 통해서 일반 OFDM과 CI/OFDM, A-CI/OFDM 시스템의 성능을 비교한다.

Keywords

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