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An Adaptive Adjacent Cell Interference Mitigation Method for Eigen-Beamforming Transmission in Downlink Cellular Systems

하향 링크 셀룰러 시스템의 Eigen-Beamforming 전송을 위한 적응적 인접 셀 간섭 완화 방법

  • Chang, Jae-Won (Department of Electronic Engineering, Sogang University) ;
  • Kim, Se-Jin (Department of Electronic Engineering, Sogang University) ;
  • Kim, Jae-Won (Department of Electronic Engineering, Sogang University) ;
  • Sung, Won-Jin (Department of Electronic Engineering, Sogang University)
  • Published : 2009.03.31

Abstract

EB(Eigen-Beamforming) has widely been applied to MIMO(Multiple-Input Multiple-Output) systems to form beams which maximize the effective signal-to-interference plus noise ratio(SINR) of the receiver using the singular value decomposition(SVD) of the MIMO channel. However, the signal detection performance for the mobile station near the cell boundary is severely degraded and the transmission efficiency decreases due to the influence of the interference signal from the adjacent cells. In this paper, we propose an adaptive interference mitigation method for the EB transmission, and evaluate the reception performance. In particular, a reception strategy which adaptively utilizes optimal combining(OC) and minimum mean-squared error for Intercell spatial demultiplexing(MMSE-lSD) is proposed, and the reception performance is investigated in terms of the effective SINR and system capacity. For the average system capacity, the proposed adaptive reception demonstrates the performance enhancement compared to the conventional EB reception using the receiver beamforming vector, and up to 2 bps/Hz performance gain is achieved for mobile station located at the cell edge.

MIMO(Multiple-Input Multiple-Output) 시스템에서 EB(Eigen-Beamforming)는 MIMO 채 널의 특이 값 분해(Singular Value Decomposition: SVD)를 통하여 수신기의 유효 신호 대 잡음비(Signal-to-Interference Plus Noise Ratio: SI-NR)를 최대화하는 빔을 형성하는 방법으로써 널리 활용되고 있으나, 인접 셀 간섭 신호의 영향으로 셀 경계에 위치한 단말기의 신호 검출 성능은 급격히 열화되고 전송 효율은 감소하게 된다. 본 논문에서는 EB 전송을 활용하는 경우, 적응적 인접 셀 간섭 완화 방안을 제시하고 그 수신 성능을 평가한다. 특히, EB 전송을 이용하여 기지국예서 전송된 신호를 단말기가 수신할 때, 최대의 유효 신호 대 간섭 잡음비를 얻기 위한 OC(Optimum Combining) 및 MMSE-ISD(Minimum Mean-Squared Error for Intercell Spatial Demultiplexing)를 적응적으로 사용하기 위한 기준을 제시하고 유효 신호 대 간섭 잡음비 및 전송 용량 측면의 수신 성능을 분석한다. 제안하는 적응적 수신 방식은 수신 빔포밍 벡터만을 사용하는 기존의 EB 수신 방식 대비 평균 전송 용량 측면에서 향상된 성능을 보이며, 셀 경계 지역에 단말기가 위치할 경우 최대 2 bps/Hz 성능 개선을 가져온다.

Keywords

References

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