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 Power Allocation for Spatial Division Multiplexing Scheme at Relays in Multiuser Distributed Beamforming Networks

다중 사용자 분산 빔포밍 네트워크의 중계기에서의 공간 분할 다중화 기법을 위한 최적 전력 할당 방법

  • 안동건 (SK텔레콤 Network기술원 Access망개발팀) ;
  • 서방원 (한국전자통신연구원 이동통신연구본부 차세대이동통신방식연구팀) ;
  • 정철 (한국과학기술원 전기및전자공학과 통신신호처리 연구실) ;
  • 김형명 (한국과학기술원 전기및전자공학과 통신신호처리 연구실)
  • Received : 2010.01.18
  • Accepted : 2010.03.31
  • Published : 2010.04.30
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Abstract

In this paper, a distributed beamforming problem is considered in an amplify-and-forward (AF) wireless relay network consist of multiple source-destination pairs and relaying nodes. To exploit degree of freedom of the number of beamformers, in the first step, we proposed that the sources transmit their signals through orthogonal channels. During the second step, the relays transmit their received signals multiplied by complex weights to amplify and compensate for phase changes introduced by the backward channels through one common channel. The optimal beamforming vectors are obtained through minimization of the total relay transmit power while the signal-to-interference-plus-noise ratios (SINRs) at the destinations are above certain thresholds to meet a quality of services (QoSs) level. In the numerical example, it is shown that the proposed scheme needs less transmit power for moderate network data rates than other schemes, such as space division multiplexing or time-division multiplexing scheme.

본 논문에서는 다수의 송수신기 쌍과 다수의 중계 노드로 구성된 분산 빔포밍 Amplify-and-Forward (AF) 중계 네트워크를 다루고 있다. 제안한 방법에서는 빔포머 수의 자유도를 높이기 위하여 첫 번째 단계에서 송신기들이 직교 채널을 이용하여 중계기로 신호를 보낸다. 두 번째 단계에서 각 중계기는 송신기로부터 받은 신호에 복소 가중치를 곱하여 신호를 증폭하고 역방향 채널에 의해 생긴 위상 변화를 조정하여 하나의 채널로 수신기에 신호를 보낸다. 최적의 빔포밍 벡터는 서비스 품질 수준을 만족시키기 위해 수신기 각각의 신호 대 간섭 및 잡음비가 특정 문턱값보다 크면서 전체 중계 전송 전력을 최소화시키도록 구하였다. 모의실험을 통해 기존의 직교 분할 다중화 방법과 공간 분할 다중화 방법에 비하여 적당히 낮은 데이터 속도 범위에서 중계 송신 전력을 줄일 수 있음을 확인하였다.

Keywords

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