전자공학회논문지 (Journal of the Institute of Electronics and Information Engineers)

대한전자공학회 (The Institute of Electronics and Information Engineers)
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MU-MIMO 하향링크 시스템에서의 MRT 기법 사용 시 에너지 효율을 최대화하는 최적 송신 안테나의 수

The Optimal Number of Transmit Antennas Maximizing Energy Efficiency in Multi-user Massive MIMO Downlink System with MRT Precoding

  • 이정수 (연세대학교 전기전자공학과) ;
  • 한용규 (연세대학교 전기전자공학과) ;
  • 이충용 (연세대학교 전기전자공학과)
  • Lee, Jeongsu (Department of Electrical and Electronic Engineering, Yonsei University) ;
  • Han, Yonggue (Department of Electrical and Electronic Engineering, Yonsei University) ;
  • Lee, Chungyong (Department of Electrical and Electronic Engineering, Yonsei University)
  • 투고 : 2014.09.23
  • 심사 : 2014.10.31
  • 발행 : 2014.11.25
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초록

본 논문에서는 다중 사용자 다중 안테나 하향링크 시스템에서 maximal ratio transmission (MRT) 기법 사용 시, 에너지 효율을 최대화하는 최적의 송신 안테나 수에 대해 알아본다. Full channel state information at the transmitter (CSIT) 환경에서 평균 채널 이득, 각 단말 간 채널 독립성, 평균 path loss를 사용하여 최적화 식을 근사하고 편미분을 이용하여 closed form으로 최적의 송신 안테나 수를 구한다. 또한 limited feedback 환경에서는 동일한 방법으로 근사한 목적함수에 대하여 bisection method를 이용하여 최적의 송신 안테나 수를 찾는다. 모의실험 결과를 통해, 구해진 최적의 송신안테나 수가 exhaustive search로 찾은 최적의 송신안테나 수에 비해 오차가 크지 않음을 확인하고, 단말의 피드백 비트 수가 최적의 송신 안테나 수에 미치는 영향을 분석한다.

We propose an optimal number of transmit antennas which maximizes energy-efficiency (EE) in multi-user massive multiple-input multiple-output (MIMO) downlink system with the maximal ratio transmission (MRT) precoding. With full channel state information at the transmitter (CSIT), we find a closed form solution by partial differential function with proper approximations using average channel gain, independence of individual channels, and average path loss. With limited feedback, we get a solution numerically by the bisection with approximations in the same manner, and analyze an effect of feedback bits on the optimal number of transmit antennas. Simulation results show that the optimal numbers of transmit antenna getting from proposed closed form solution and exhaustive search are nearly same.

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참고문헌

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