대한전자공학회논문지TC (Journal of the Institute of Electronics Engineers of Korea TC)

대한전자공학회 (The Institute of Electronics and Information Engineers)
권호 표지

차분 선부호화 구조를 적용한 LTE-A 상향링크 시스템의 성능분석

Preformance Analysis of LTE-A System Uplink with Differential Precoding Scheme

  • 이신 (충북대학교 정보통신공학과) ;
  • 박노윤 (충북대학교 정보통신공학과) ;
  • 김영주 (충북대학교 정보통신공학과)
  • Li, Xun (School of Information and Communication Engineering, Chungbuk National University) ;
  • Park, Noe-Yoon (School of Information and Communication Engineering, Chungbuk National University) ;
  • Kim, Young-Ju (School of Information and Communication Engineering, Chungbuk National University)
  • 투고 : 2012.03.22
  • 심사 : 2012.05.12
  • 발행 : 2012.05.25
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초록

LTE 시스템에서는 폐회로 기반의 다중 안테나 기술이 적용되었으며, 차분 코드북을 비롯한 다양한 다중 안테나 기반의 선부호화 기술들이 향상된 LTE (LTE-Advanced) 시스템의 요구조건을 만족시키기 위해 제안되었다. 차분 코드북 설계와 관련하여 이전에 연구된 내용은 준 대각(quasi-diagonal) 단위 행렬 및 구면 캡(spherical cap)에 중점을 두었지만, 이는 동 이득 성질을 만족하지 못한다. 동 이득 성질은 특히 상향 링크에서 첨두 전력 대 평균 전력비 (PAPR)에 상당한 영향을 미치므로 매우 중요하다. 본 논문에서는 각 송신 안테나에 동 이득을 유지하는 성질을 이용한 새로운 차분 코드북을 상향 링크 기반 차분 선부호화 시스템에 적용하고, 이를 통해 비트 오류율(BER)과 첨두 전력 대 평균 전력비를 분석하였다. 특히, 송신기의 비선형 증폭기를 고려하여 다양한 차분 선부호화 기법들의 성능을 분석하였다. 모의 실험을 통해 선형 증폭기를 고려할 경우 기존에 제안된 차분 코드북이 우수한 성능을 보이지만, 비선형 증폭기를 고려할 경우에는 제안하는 차분 코드북의 우수함을 증명하였다.

The closed-loop multiple-input multiple-output (MIMO) system has been adopted by long term evolution (LTE) system. Many techniques are proposed to enhance the transmission of LTE's advanced version to meet the increasing requirement, in which differential codebook gains a lot of interest. Previous researches on designing differential codebooks focused on quasi-diagonal unitary matrix which cannot guarantee the equal gain property. The equal gain property is very important to uplink because the performance of uplink is very sensitive to the peak-to-average power ratio (PAPR). In this paper, we derive the analytical expression of average bit error rate and PAPR for differential precoding MIMO system. Using the analytical results, we investigate the performances of several differential precoding schemes considering non-linear amplifier at the transmitter. Some selected simulation results indicate that the conventional differential precoding schemes have good performances without the consideration of non-linear amplifier. While considering non-linear amplifier, the proposed differential codebook outperforms other differential precoding schemes because it maintains the equal gain per transmit antenna.

키워드

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