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

The Korean Institute of Commucations and Information Sciences (한국통신학회)
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Optimal Numbers of Base Station Antennas and Users in Multiuser Massive MIMO Systems with Pilot Overhead

다중 사용자 Massive MIMO 시스템의 파일럿 오버헤드를 고려한 최적 기지국 안테나 수 및 사용자 수 분석

  • Jung, Minchae (School of Electrical and Electronic Engineering, Yonsei University) ;
  • Choi, Sooyong (School of Electrical and Electronic Engineering, Yonsei University)
  • Received : 2016.09.26
  • Accepted : 2016.11.23
  • Published : 2016.11.30
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Abstract

In this paper, we consider multiuser massive multiple-input and multiple-output (MIMO) system where multiusers simultaneously utilize massive antennas of base station (BS). With a downlink frame structure considering pilot signals, we derive the ergodic cell capacity based on zero-forcing beamforming (ZFBF) technique. This paper proves that the ergodic cell capacity is concave function with respect to the numbers of BS antennas and users, and derives the optimum numbers of BS antennas and users maximizing ergodic cell capacity. From the simulation results, it is shown that the derived numbers of BS antennas and users has the optimum value for the maximum ergodic cell capacity, and the ergodic cell capacity with the derived optimum values increases with respect to the transmit SNR(Signal to Noise Ratio).

본 논문에서는 다중 사용자(multiuser)가 다수의 기지국 안테나(MIMO, Multiple-Input and Multiple-Output)를 동시에 사용하는 다중 사용자 massive MIMO 시스템 환경을 고려한다. 다중 사용자를 동시에 지원하기 위해 기지국에서는 ZFBF(Zero-Forcing Beamforming) 기법을 고려하고 수신 신호 검출을 위해 파일럿 신호를 고려한 하향 링크 프레임 구조를 적용하여 평균 셀 용량을 도출한다. 평균 셀 용량은 기지국 안테나 수 및 사용자 수에 대해 오목 함수 (concave function)임을 수식적으로 증명하고, 오목 함수 특징을 통해 최적의 기지국 안테나 수 및 사용자 수를 도출한다. 실험 결과를 통해 수식적으로 도출한 최적 값을 검증하고, 최적값 기반의 평균 셀 용량은 송신 SNR(Signal to Noise Ratio)에 비례하여 증가함을 확인할 수 있다.

Keywords

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