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

한국통신학회 (The Korean Institute of Commucations and Information Sciences)
권호 표지

OFDM 시스템에서 PAPR 감소를 위한 피크 신호 관찰 기반의 적응적 SLM 기법

An Adaptive SLM Scheme Based on Peak Observation for PAPR Reduction in OFDM Systems

  • 양석철 (숭실대학교 정보통신전자공학부) ;
  • 신요안 (숭실대학교 정보통신전자공학부)
  • 발행 : 2007.12.31
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초록

본 논문에서는 OFDM (Orthogonal Frequency Division Multiplexing) 시스템에서 전송 신호의 PAPR(Peak-to-Average Power Ratio)을 효과적으로 감소시키기 위한 피크 신호 관찰 기반의 적응적 SLM (Adaptive Selective Mapping; ASLM) 기법을 제안한다. 제안 기법은 기존 SLM 방법에서의 복잡도 문제를 개선하기 위해, 매 OFDM 심벌마다 IFFT (Inverse Fast Fourier Transform) 결과에 대한 피크 신호 조정, 피크 조정된 신호의 FFT 결과와 원래 OFDM 심벌간의 부반송파별 전력차 비교를 통한 직교 부호 선택, 선택된 직교 부호만을 이용한 전형적인 SLM 과정의 3단계로 구성된다. 모의실험 결과, 제안된 ASLM 기법은 우수한 PAPR 감소 성능을 유지하면서도 기존 SLM 방법에 비해 훨씬 적은 IFFT 연산 및 PAPR 계산 횟수를 요구함을 확인하였다.

In this paper, we propose ASLM (Adaptive Selective Mapping; ASLM) scheme based on peak observation for PAPR (Peak-to-Average Power Ratio) reduction of OFDM (Orthogonal Frequency Division Multiplexing) signals. The proposed scheme is composed of three steps: peak scaling, sequence selection, and SLM procedures. In the first step, the peak signal samples in the IFFT (Inverse Fast Fourier Transform) outputs of the original input sequence are scaled down. In the second step, the sub-carrier positions where the power difference between the original input sequence and the FFT output of the scaled signal is large, are identified. Then, the phase sequences having the maximum number of phase-reversed sequence words only for these positions are selected. Finally, the generic SLM procedure is performed by using only the selected phase sequences for the original input sequence. Simulation results show that the proposed scheme significantly reduces the complexity in terms of IFFT and PAPR calculation than the conventional SLM, while maintaining the PAPR reduction performance.

키워드

참고문헌

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