• 제목/요약/키워드: Multiuser-MIMO

검색결과 123건 처리시간 0.026초

High-performance TDM-MIMO-VLC Using RGB LEDs in Indoor Multiuser Environments

  • Sewaiwar, Atul;Chung, Yeon-Ho
    • Current Optics and Photonics
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    • 제1권4호
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    • pp.289-294
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    • 2017
  • A high-performance time-division multiplexing (TDM) -based multiuser (MU) multiple-input multipleoutput (MIMO) system for efficient indoor visible-light communication (VLC) is presented. In this work, a MIMO technique based on RGB light-emitting diodes (LEDs) with selection combining (SC) is utilized for data transmission. That is, the proposed scheme employs RGB LEDs for parallel transmission of user data and transmits MU data in predefined slots of a time frame with a simple and efficient design, to schedule the transmission times for multiple users. Simulation results demonstrate that the proposed scheme offers an approximately 6 dB gain in signal-to-noise ratio (SNR) at a bit error rate (BER) of $3{\times}10^{-5}$, as compared to conventional MU single-input single-output (SISO) systems. Moreover, a data rate of 66.7 Mbps/user at a BER of $10^{-3}$ is achieved for 10 users in indoor VLC environments.

Performance Analysis of a Two-Hop Fixed-Gain MIMO Multiuser Relay Network with End-to-End Antenna Selection

  • Li, Guangping;Blostein, Steven David;Zhang, Guangchi;Feng, Jiuchao
    • ETRI Journal
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    • 제34권2호
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    • pp.264-267
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    • 2012
  • This letter analyzes the performance of a two-hop MIMO multiuser relay network with a fixed gain amplify-and-forward protocol and antenna selection at the transmitter and receiver. A new expression for the cumulative distribution function of the highest instantaneous end-to-end signal-to-noise ratio is derived. Based on the above result, closed-form expressions for outage probability and bit error rate are presented. Also, the diversity order of the system is determined. Finally, computer simulations are compared to the analytical results, and insights and observations are provided.

Blind downlink channel estimation for TDD-based multiuser massive MIMO in the presence of nonlinear HPA

  • Pasangi, Parisa;Atashbar, Mahmoud;Feghhi, Mahmood Mohassel
    • ETRI Journal
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    • 제41권4호
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    • pp.426-436
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    • 2019
  • In time division duplex (TDD)-based multiuser massive multiple input multiple output (MIMO) systems, the uplink channel is estimated and the results are used in downlink for signal detection. Owing to noisy uplink channel estimation, the downlink channel should also be estimated for accurate signal detection. Therefore, recently, a blind method was developed, which assumes the use of a linear high-power amplifier (HPA) in the base station (BS). In this study, we extend this method to a scenario with a nonlinear HPA in the BS, where the Bussgang decomposition is used for HPA modeling. In the proposed method, the average power of the received signal for each user is a function of channel gain, large-scale fading, and nonlinear distortion variance. Therefore, the channel gain is estimated, which is required for signal detection. The performance of the proposed method is analyzed theoretically. The simulation results show superior performance of the proposed method compared to that of the other methods in the literature.

Novel Turbo Receiver for MU-MIMO SC-FDMA System

  • Wang, Hung-Sheng;Ueng, Fang-Biau;Chang, Yu-Kuan
    • ETRI Journal
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    • 제40권3호
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    • pp.309-317
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    • 2018
  • Single carrier-frequency-division multiple access (SC-FDMA) has been adopted as the uplink transmission standard in fourth-generation cellular networks to facilitate power efficiency transmission in mobile stations. Because multiuser multiple-input multiple-output (MU-MIMO) is a promising technology employed to fully exploit the channel capacity in mobile radio networks, this study investigates the uplink transmission of MU-MIMO SC-FDMA systems with orthogonal space-frequency block codes (SFBCs). It is preferable to minimize the length of the cyclic prefix (CP). In this study, the chained turbo equalization technique with chained turbo estimation is employed in the designed receiver. Chained turbo estimation employs a short training sequence to improve the spectrum efficiency without compromising the estimation accuracy. In this paper, we propose a novel and spectrally efficient iterative joint-channel estimation, multiuser detection, and turbo equalization for an MU-MIMO SC-FDMA system without CP-insertion and with short TR. Some simulation examples are presented for the uplink scenario to demonstrate the effectiveness of the proposed scheme.

다중사용자 다중입출력 하향링크 채널에서 인접셀 간섭을 고려한 MMSE 기반 비선형 프리코딩 (MMSE Based Nonlinear Precoding for Multiuser MIMO Broadcast Channels with Inter-Cell Interference)

  • 이경재;성학제;이인규
    • 한국통신학회논문지
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    • 제41권8호
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    • pp.896-902
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    • 2016
  • 본 논문에서는 다른 셀로부터 발생하는 간섭을 고려하여 다중사용자 다중안테나 하향링크 채널에서 최소평균제곱오차(MMSE: minimum mean-squared error)에 기반한 비선형 연속 프리코딩(precoding) 기법을 제안한다. 기존의 zero forcing(ZF) 기반의 방법과 달리 제안하는 방식은 다른 셀로부터의 간섭을 고려하여 셀 내의 다중사용자 간섭을 억제하는 방식을 취하여 수신단에서의 신호 대 간섭 잡음비를 향상시킬 수 있다. 모의 실험 결과를 통해 제안하는 최소평균제곱오차에 기반한 비선형 전처리 기법이 다양한 셀 간섭 환경에서 기존 방법보다 좋은 성능을 가지는 것을 확인할 수 있다.

협력적 공간다중화 기반 상향링크 다중사용자 시스템을 위한 신호검출 기법 (A Signal Detection Method for Uplink Multiuser Systems Based on Collaborative Spatial Multiplexing)

  • 임태호;김영준;정재훈;조용수
    • 한국통신학회논문지
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    • 제35권2C호
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    • pp.229-237
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    • 2010
  • 기존 SM MIMO 시스템을 위한 신호검출 기법인 OSIC 계열의 기법과 준최적 신호검출 기법인 QRD-M 기법을 협력적 공간다중화 기반 상향링크 다중사용자 시스템에 적용할 경우 사용자별 신호의 검출성능에 차이가 발생한다. 본 논문에서는 협력적 공간다중화 기반 상향링크 다중사용자 시스템을 위한 사용자간별 검출성능 차이가 발생하지 않으면서 최적 신호검출 기법과 유사한 성능을 보이는 신호검출 기법을 제안한다. 제안된 신호검출 기법의 연산복잡도는 QPSK 변조에서는 QRD-M과 유사하지만, 16-QAM, 64-QAM과 같이 높은 차수의 변조방식의 시스템에서는 QRD-M에 비해 매우 낮은 연산복잡도를 가진다.

MIMO-OFDM 시스템에서 다중사용자 다이버시티 기술의 성능분석 (An Analysis of Multiuser Diversity Technology in the MIMO-OFDM System)

  • 장기;서희종
    • 한국전자통신학회논문지
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    • 제14권6호
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    • pp.1121-1128
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    • 2019
  • 본 논문에서는 OFDM과 MIMO 기술의 응용을 기술하고, 이 기술이 고속인 무선이동통신에 적합함을 설명하였다. OFDM 변조기, 복조기와 MIMO-OFDM 시스템을 블록화하여 설명하였다. MIMO-OFDM 시스템에서 다이버시티 기술을 연구하고 성능을 분석하였다. 이 성능분석을 위해서 모의실험을 하였다.

Channel Quantization for Block Diagonalization with Limited Feedback in Multiuser MIMO Downlink Channels

  • Moon, Sung-Hyun;Lee, Sang-Rim;Kim, Jin-Sung;Lee, Inkyu
    • Journal of Communications and Networks
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    • 제16권1호
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    • pp.1-9
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    • 2014
  • Block diagonalization (BD) has been proposed as a simple and effective technique in multiuser multiple-input multiple-output (MU-MIMO) broadcast channels. However, when channel state information (CSI) knowledge is limited at the transmitter, the performance of the BD may be degraded because inter-user interference cannot be completely eliminated. In this paper, we propose an efficient CSI quantization technique for BD precoded systems with limited feedback where users supported by a base station are selected by dynamic scheduling. First, we express the received signal-to-interference-plus-noise ratio (SINR) when multiple data streams are transmitted to the user, and derive a lower bound expression of the expected received SINR at each user. Then, based on this measure, each user determines its quantized CSI feedback information which maximizes the derived expected SINR, which comprises both the channel direction and the amplitude information. From simulations, we confirm that the proposed SINR-based channel quantization scheme achieves a significant sum rate gain over the conventional method in practical MU-MIMO systems.

다중입출력 직교 주파수 분할 다중접속 시스템에서 제로포싱 빔형성을 이용한 다중안테나 부반송파 할당 방법 (Multi-antenna Subcarrier Allocation Using Zero-Forcing Beamforming in MIMO-OFDM Systems)

  • 신영일;강태성;김형명
    • 한국통신학회논문지
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    • 제32권10A호
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    • pp.974-983
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    • 2007
  • 본 논문에서는 제로포싱 빔형성 (ZFBF)을 이용한 Multiuser MIMO-OFDM 시스템에서 각 사용자의 주어진 요구정보량을 만족시키면서 총송신전력을 최소화하기 위한 부반송파 할당방법을 제안한다. 최적 방법의 복잡도는 부반송파의 수에 지수적으로 비례하여 증가하기 때문에 복잡도를 줄이기 위한 부최적 방법을 제안한다. 부최적 방법에서는 사용자 그룹의 채널간 직교도가 클수록 유효채널이득이 증가하는 특성을 이용하여 채널간 직교도가 큰 사용자 그룹을 할당함으로써 송신전력을 최소화한다. 모의실험 결과에서 제안한 부최적 방법이 복잡도를 현저히 감소시키면서 총 송신전력의 측면에서는 최적화된 방법과 유사한 성능을 가진다는 것을 보인다.

하향링크 다중 사용자 MIMO 시스템에서의 일반화된 사용자 선택 알고리즘 (Generalized User Selection Algorithm im Downlink Multiuser MIMo System)

  • 강대근;신창의;금동현;최승원
    • 디지털산업정보학회논문지
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    • 제8권4호
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    • pp.99-105
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    • 2012
  • Recently, there are many user selection algorithms in multi user multiple-input multiple-output (MU-MIMO) systems. One of well-known user selection methods is Semi orthogonal user selection (SUS). It is an algorithm maximizing channel capacity. However, it is applicable only when user's antenna is one. We propose a generalized user selection algorithm regardless of the number of user's antennas. In the proposed scheme, Base station (Bs) selects the first user who has the highest determinant of channel and generates a user group that correlation with first user's channel is less than allowance of correlation. Then, each determinant of channels made up of first user's channel and a user's channel in the generated group is calculated and BS selects the next user who has the highest determinant of that. BS selects following users by repeating above procedure. In this paper, we get better performance because of selecting users who have the highest determinant of channel as well as allowance of correlation optimally calculated through matrix operations.