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

The Korean Institute of Electromagnetic Engineering and Science (한국전자파학회)
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Design and Analysis of 4D-8PSK-TCM System Considering the Nonlinear HPA Environment

비선형 HPA 환경을 고려한 4D-8PSK-TCM 시스템의 설계 및 분석

  • An, Changyoung (Department of Electronics Engineering, Chungbuk National University) ;
  • Ryu, Sang-Burm (Payload Electronics Team, Korea Aerospace Research Institute) ;
  • Lee, Sang-Gyu (Payload Electronics Team, Korea Aerospace Research Institute) ;
  • Ryu, Heung-Gyoon (Department of Electronics Engineering, Chungbuk National University)
  • 안창영 (충북대학교 전자공학과) ;
  • 유상범 (한국항공우주연구원 탑재체전자팀) ;
  • 이상규 (한국항공우주연구원 탑재체전자팀) ;
  • 유흥균 (충북대학교 전자공학과)
  • Received : 2017.10.13
  • Accepted : 2018.03.08
  • Published : 2018.04.30
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Abstract

Considering a nonlinear high power amplifier(HPA) and a predistorter, we have designed a four-dimensional 8-ary phase shift keying trellis-coded modulation(4D-8PSK-TCM) system, which is recommended for X-band satellite communications. Subsequently, we have evaluated and analyzed the spectrum, constellation characteristics, and BER performance of the system. In satellite communications, owing to the limited power, nonlinear characteristics that determine the operating point of the HPA must be analyzed because the HPA consumes high power. We herein report the design of the 4D-8PSK-TCM system, with efficiencies of 2 and 2.25 bits/channel-symbol. The simulation results confirmed that a 0.35 roll-off value is effective, considering the low peak-to-average power ratio(PAPR) characteristic and the narrow occupation bandwidth of the spectrum. It also confirmed that approximately 15~20 dB of output backoff(OBO) value is required at the HPA when the predistorter is not used, and approximately 1 dB of the OBO value is required when the predistorter is used.

본 논문에서는 X밴드 위성통신을 위해 권고되는 4D-8PSK-TCM(Four Dimensional 8-ary Phase Shift Keying Trellis Coded Modulation) 시스템을 비선형 HPA(High Power Amplifier)와 전치왜곡기를 고려하여 설계하고, 스펙트럼, BER(Bit Error Rate) 성능을 평가 및 분석한다. 위성통신에서는 한정적인 전력으로 인해 전력을 가장 많이 소모하는 HPA의 동작점을 결정하는 비선형 특성 분석이 매우 중요하다. 본 논문에서는 2, 2.25 bits/channel-symbol의 효율을 갖는 4D-8PSK-TCM 시스템을 설계하였다. 시뮬레이션 결과로, 낮은 PAPR(Peak to Average Power Ratio) 특성과, 스펙트럼의 점유 대역폭을 기준으로 SRRC(Square Root Raised Cosine) 필터의 Roll-off 값은 0.35가 효율적이며, 전치왜곡기를 사용하지 않을 경우 HPA에서 약 15~20 dB의 OBO(Output Back-Off)가 요구되며, 전치왜곡기를 사용할 경우 약 1 dB 내외의 OBO가 요구됨을 확인하였다.

Keywords

References

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