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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Parallel M-band DWT-LMS Algorithm to Improve Convergence Speed of Nonlinear Volterra Equalizer in MQAM System with Nonlinear HPA

비선형 HPA를 가진 M-QAM 시스템에서 비선형 Volterra 등화기의 수렴 속도 향상을 위한 병렬 M-band DWT-LMS 알고리즘

  • 최윤석 (삼성전자 통신연구소) ;
  • 박형근 (한국기술교육대학교 정보기술공학부)
  • Published : 2007.07.31
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Abstract

When a higher-order modulation scheme (16QAM or 64QAM) is applied to the communications system using the nonlinear high power amplifier (HPA), the performance can be degraded by the nonlinear distortion of the HPA. The nonlinear distortion can be compensated by the adaptive nonlinear Volterra equalizer using the low-complexity LMS algorithm at the receiver. However, the LMS algorithm shows very slow convergence performance. So, in this paper, the parallel M-band discrete wavelet transformed LMS algorithm is proposed in order to improve the convergence speed. Throughout the computer simulations, it is shown that the convergence performance of the proposed method is superior to that of the conventional time-domain and transform-domain LMS algorithms.

고효율 변조기법 (16 QAM or 64QAM)이 비선형 고전력 증폭기 (High-Power Amplifier; HPA)를 사용하는 통신시스템에 적용되었을 때 비선형 왜곡에 의해 성능저하가 발생할 수 있다. 이런 비선형 왜곡은 수신부에서 복잡도가 낮은 LMS 알고리즘을 적용한 적응적 비선형 Volterra 등화기를 사용하여 보상할 수 있지만, 매우 느린 수렴 속도를 가지는 단점이 있다. 본 논문에서는 수렴 속도를 향상시키기 위한 병렬 M대역 이산 웨이블릿 변환영역 LMS (Parallel M-band Discrete Wavelet Transform Least Mean Square) 알고리즘을 제안한다. 모의실험을 통하여 제안된 기법이 기존의 시간 영역 LMS 알고리즘과 변환 영역 LMS 알고리즘들에 비해 수렴 속도가 우수함을 보여준다.

Keywords

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