• Title/Summary/Keyword: 다중빔

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Limited Feedback Technique for Symbol-Based Beamforming (심볼 기반 빔포밍을 위한 제한 피드백 기법)

  • Lee, Hyun-Ho;Ko, Young-Chai
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2010.11a
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    • pp.214-216
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    • 2010
  • 본 논문에서는, 다중송수신안테나 직교주파수분할다중화 (MIMO-OFDM) 시스템에서 심볼 기반 빔포밍을 위한 제한 피드백 기법을 고려하였다. 공간적 상관도가 존재하는 다중전달경로 채널에서, 심볼 기반 빔포밍을 위한 제한 피드백 기법과 코드북을 제안하였다. 모의실험 결과를 통해 제안한 기법이 낮은 복잡도를 가짐에도 불구하고 기존의 iterative 알고리즘을 기반으로 하는 심볼 기반 빔포밍을 이용한 제한 피드백 기법보다 우수한 성능을 보임을 확인하였다. 또한, 제안한 코드북이 랜덤 벡터 양자화 코드북보다 우수한 성능을 보임을 확인하였다.

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Mode Selection Technique Between Antenna Grouping and Beamforming for MIMO Communication Systems (다중 입출력 시스템에서 안테나 그룹화와 빔 형성 사이의 모드 선택 기법)

  • Kim, Kyung-Chul;Lee, Jung-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.34 no.2A
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    • pp.147-154
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    • 2009
  • Antenna grouping algorithm is hybrid of beamforming and spatial multiplexing. In antenna grouping system, we partition $N_t$ transmit antennas into $N_r$ groups and use beamforming in a group, spatial multiplexing between groups. We can transmit $N_r$ data streams in the $N_t{\times}N_r$ antenna grouping system. With antenna grouping, we can achieve diversity gain through beamforming, and high spectral efficiency through spatial multiplexing. But if channel is ill-conditioned or there are some correlations between antennas, the performance of antenna grouping is seriously degraded and in that case, beamforming is the best transmit strategy. By selecting the antenna grouping mode when channel is well-conditioned and by selecting the beamforming mode when channel is ill-conditioned, we can prevent serious fluctuation of BER performance caused by varying channel condition and achieve the best BER performance. In this paper, we investigate mode selection algorithm which can select antenna grouping mode or beamforming mode. we also propose a simple mode selection criterion.

Performance of MIMO-OFDMA Systems with Multibeamforming Algorithm (다중빔 형성기법을 가진 MIMO-OFDMA시스템 성능)

  • Kim, Chan-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.36 no.4A
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    • pp.303-311
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    • 2011
  • In this paper, we propose the adaptive multibeamforming algorithm to remove the same subcarrier interference and multipath signals in the MIMO(Multi-Input Multi-Out)-OFDMA (Orthogonal Frequency Division Multiplexing Access)system allocated the same subcarrier partially in order to improve spectrum efficiency. In addition to removing the interference, we can get diversity gain and combat the detriment of the performance according to time delay by the proposed approach. BER performance improvement and combating the delay spread detrimental effects of the proposed approach is investigated through computer simulation by applying it to MIMO-OFDMA.

Iterative Weighted MMSE Beamforming for Downlink multiuser MISO System (하향링크 다중사용자 다중안테나 시스템을 지원하는 반복 가중치 최소평균자승오류 빔형성 기법)

  • Choi, Ilgyu;Hwang, Youngsoo;Lee, Chungyong
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.3
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    • pp.3-8
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    • 2013
  • Conventional MMSE beamforming scheme shows better performance than ZF or MF beamforming, but it does not aim increase of sum rate. This paper proposes sum rate maximizing scheme by representing sum rate as a function of weighted MSE. Proposed scheme increases sum rate iteratively by updating weights and beam whose initial form is conventional MMSE beam. Simulation result shows sum rate of proposed scheme is higher than those of conventional schemes and increases as the number of users increases.

English Performance of MIMO-OFDM Combing Bemaformer with Space-time Decoder in Multiuser Environments (다중 사용자 환경에서 빔 형성기와 결합된 Space-Time decoder을 가진 MIMO-OFDM 시스템의 성능)

  • Kim Chan-Kyu
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.8A
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    • pp.775-783
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    • 2006
  • In this paper, the new technique combining beamforming with space-time coding is proposed for an orthogonal frequency division multiplexing(OFDM) system with multi-input multi-output(MIMO). When MIMO-OFDM system is employing Nt(the number of transmitterantenna) beamfomers and one S-T decoder at Nr receiver antennas, Nt signals removed CCI are outputted at the beamformer and then diversity gain can be got through space-time decoding. As the proposed technique can reduce cochannel interference and get diversity gain in the multi-user environment, the performance of MIMO-OFDM system is very improved. BER performance improvement and convergence behavior of the proposed approach are investigated through computer simulation by applying it to MIMO-OFDM system in the multi-user environment.

Hybrid Beamformer of CDMA Reverse Link in the Correlated SIMO Channel (CDMA 역방향 링크의 상관된 SIMO 채널을 위한 복합형 빔 성형 방식)

  • 최영관;김동구
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.11
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    • pp.81-86
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    • 2004
  • Hybrid beamformer composed of Direction-of-Arrival (DOA) based scheme followed by Maximal Ratio Combining (MRC) is proposed to overcome the degradation due to inaccurate channel estimation caused by insufficient pilot power, which happens in conventional Single-Input Multiple-Output (SIMO) Code Division Multiple Access (CDMA) reverse link. The proposed scheme could provide more accurate channel estimation and interference reduction at the expense of diversity gam in the spatially correlated SIMO channel. As a result, hybrid scheme outperforms conventional MRC beamformer for six or more antennas in the channel environment, in which Angle-of-Spread (AOS) is within 30$^{\circ}$.

Simultaneous Transmission of Multiple Unicast and Multicast Streams Using Non-orthogonal Multiple Access (비직교 다중접속 방식을 이용한 다중 유니캐스트와 멀티캐스트 스트림 동시 전송)

  • Shin, Changyong
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.22 no.2
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    • pp.11-19
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    • 2021
  • In this paper, we propose a non-orthogonal multiple access (NOMA) method based on channel alignment to simultaneously transmit multiple unicast and multicast streams in frequency-efficient manner. In this method, all receivers in a multicast cluster use the receive beamforming vectors that align their channels, and the base station uses the aligned channel information to design the transmit beamforming vectors that eliminate interference between multicast clusters. Using the effective receive channel information combined with the transmit beamforming vectors, unicast receivers design their own receive beamforming vectors that eliminate interference between unicast receivers. Since the proposed method effectively eliminates the interference, it achieves a higher sum rate than the existing orthogonal multiple access (OMA) method in high SNR regions. In addition, we present a hybrid method that exploits the benefits of the proposed NOMA method and the existing OMA method. Depending on the channel state, the hybrid method adaptively employs the existing OMA method, which improves the received signal power, in low SNR regions and the proposed NOMA method, which effectively eliminates the interference, in high SNR regions, thereby achieving a good sum rate over the entire SNR region.

A preliminary study on the development of detection techniques for CO2 gas bubble plumes (CO2 가스 기포 누출 탐지 기술 개발을 위한 예비 연구)

  • Kum, Byung-Cheol;Cho, Jin Hyung;Shin, Dong-Hyeok
    • Journal of Advanced Marine Engineering and Technology
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    • v.38 no.9
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    • pp.1163-1169
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    • 2014
  • As a preliminary study for detection techniques of $CO_2$ gas bubble plumes, we have conducted a comparative experiment on artificially generated $CO_2$ gas bubbles plume by using multibeam echosounder (MBES), single beam echosounder (SBES), and sub-bottom profiler (SBP). The rising speed of artificial gas bubbles is higher than references because of compulsory release of compressed gas in the tank. Compared to single beam acoustic equipments, the MBES detects wide swath coverage. It provides exact determination of the source position and 3D information on the gas bubble plumes in the water column. Therefore, it is shown that MBES can distinctly detect gas bubble plumes compared to single beam acoustic equipments. We can establish more effective complementary detection technique by simultaneous operation of MBES and SBES. Consequently, it contributes to improve qualitative and quantitative detection techniques by understanding the acoustic characteristics of the specific gas bubbles.

Study on a Optical Storage Device Based on Multi-beam (다중빔을 이용한 광 저장 장치에 관한 연구)

  • Lee, Jeong-Hyeon;Han, Chang-Su;Kim, Su-Hyeon;Gwak, Yun-Geun
    • Journal of the Korean Society for Precision Engineering
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    • v.16 no.4 s.97
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    • pp.64-70
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    • 1999
  • A new multi-beam optical system is presented on the grounds of tri-positioning systems in this paper. The system has been developed to improve the data transfer rate for the optical disk system. The actuating system is composed of a tracking and focusing actuating system basically and a newly developed beam rotating actuator. The beam rotating actuator is employed in a multi-beam optical system to trace more than one track simultaneously. The multi-beam optics is established through the optical simulation and several experimental trials. The differential phase tracking method is used in the tracking error signal detection based on the only one beam spot. We also analyze the characteristics of multi-beam optical system. The experimental result shows that the multi-beam positioning system has performance adequate to the multi-beam optical disk system.

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Research of Disaster Surveying for Breakwater using MBES (다중빔 수심측량을 이용한 방파제 피해조사에 관한 연구)

  • Park, Hyeong-Geun;Park, Jae-Kook;Kim, Dong-Mun;Yang, In-Tae
    • Journal of the Korean Society of Hazard Mitigation
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    • v.8 no.1
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    • pp.125-131
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    • 2008
  • A lot of breakwater shall be damaged by typhoon and ocean wave under construction. Construction company shall sign up for onshore & offshore construction insurance regarding disaster. But in case of breakwater it is very difficult to calculate exactly about damaged quantity. In research effective quantity for disaster survey shall be investigated and calculated by multibeam bathymetric survey.