• Title/Summary/Keyword: MIMO Systems

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Study on the applicability of MIMO Joint Decoding to Dual-Contact Satellite Systems (이중 교신 위성 시스템의 MIMO 공동 복조의 적용성에 대한 연구)

  • Park, Hong Won;Kim, Whan Woo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.46 no.10
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    • pp.856-867
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    • 2018
  • This paper presents the applicability of MIMO joint decoding to dual-contact satellite systems in which two LEO satellites using X-band frequency band are transmitting each image data to two ground station antennas, simultaneously. When two satellites are closely positioned within the looking angle of the two antennas, each satellite interferes with each other by the relative antenna gain corresponding to an offset angle and this might cause the performance degradation without interference mitigation. To mitigate the performance degradation, SM MIMO techniques for joint decoding are applied. Especially, the relative antenna gain of ground station depending on the angle difference between two satellites in ground station antenna plays an important role in modelling the dual-contact satellite systems. The condition number of MIMO channel including the antenna gain calculated from the mathematical gain pattern model was primarily analyzed. Simulation results showed that the SM MIMO techniques using detection schemes such as ZF-SIC, MMSE-SIC, and ML can be applicable to dual-contact satellite systems.

Performance Analysis and Design of MIMO Systems for Terrestrial Transmission of UHDTV (UHDTV를 위한 MIMO 전송 시스템 성능 분석 및 설계)

  • Jo, Bong-Gyun;Han, Dong-Seog
    • Journal of Broadcast Engineering
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    • v.15 no.4
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    • pp.547-554
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    • 2010
  • In this paper, we propose transmission systems for ultra high definition television (UHDTV) through terrestrial transmission by applying the multi-input multi-output (MIMO) technology. The space time block code, hybrid STBC, V-BLAST and linear dis- persion code are considered to support a high data rate of the UHDTV system. The performance of proposed MIMO systems are evaluated through computer simulations. Then we suggest MIMO parameters, number of antennas and optimal transmission scheme to achieve the transmission rate of the UHDTV system.

Low-Complexity MIMO Detection Algorithm with Adaptive Interference Mitigation in DL MU-MIMO Systems with Quantization Error

  • Park, Jangyong;Kim, Minjoon;Kim, Hyunsub;Jung, Yunho;Kim, Jaeseok
    • Journal of Communications and Networks
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    • v.18 no.2
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    • pp.210-217
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    • 2016
  • In this paper, we propose a low complexity multiple-input multiple-output (MIMO) detection algorithm with adaptive interference mitigation in downlink multiuser MIMO (DL MU-MIMO) systems with quantization error of the channel state information (CSI) feedback. In DL MU-MIMO systems using the imperfect precoding matrix caused by quantization error of the CSI feedback, the station receives the desired signal as well as the residual interference signal. Therefore, a complexMIMO detection algorithm with interference mitigation is required for mitigating the residual interference. To reduce the computational complexity, we propose a MIMO detection algorithm with adaptive interference mitigation. The proposed algorithm adaptively mitigates the residual interference by using the maximum likelihood detection (MLD) error criterion (MEC). We derive a theoretical MEC by using the MLD error condition and a practical MEC by approximating the theoretical MEC. In conclusion, the proposed algorithm adaptively performs interference mitigation when satisfying the practical MEC. Simulation results show that the proposed algorithm reduces the computational complexity and has the same performance, compared to the generalized sphere decoder, which always performs interference mitigation.

Review of Channel Quality Indicator Estimation Schemes for Multi-User MIMO in 3GPP LTE/LTE-A Systems

  • Abdulhasan, Muntadher Qasim;Salman, Mustafa Ismael;Ng, Chee Kyun;Noordin, Nor Kamariah;Hashim, Shaiful Jahari;Hashim, Fazirulhisham
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.8 no.6
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    • pp.1848-1868
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    • 2014
  • Multiple-in multiple-out (MIMO) in long-term evolution (LTE) is an essential factor in achieving high speed data rates and spectral efficiency. The unexpected growth in data rate demand has pushed researchers to extend the benefits of multi-user MIMO. The multi-user MIMO system can take full advantage of channel conditions by employing efficient adjustment techniques for scheduling, and by assigning different modulation and coding rates. However, one of the critical issues affecting this feature is the appropriate estimation of channel quality indicator (CQI) to manage the allocated resources to users. Therefore, an accurate CQI estimation scheme is required for the multi-user MIMO transmission to obtain significant improvements on spectral efficiency. This paper presents overviews of multi-user MIMO in LTE/LTE-advanced systems. The link adaptation, scheduling process, and different factors that affect the reliability of CQI measurements are discussed. State-of-the-art schemes for the post-processing CQI estimation, and the comparisons of various CQI estimation schemes to support multi-user MIMO are also addressed.

Co-located and space-shared multiple-input multiple-output antenna module and its applications in 12 × 12 multiple-input multiple-output systems

  • Longyue Qu;Haiyan Piao;Guohui Dong
    • ETRI Journal
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    • v.45 no.2
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    • pp.203-212
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    • 2023
  • In this study, we developed a co-located and space-shared multiple-input multiple-output (MIMO) antenna module with a modular design and high integration level. The proposed antenna pair includes a half-wavelength loop antenna and a dipole-type antenna printed on the front and back sides of a compact modular board. Owing to their modal orthogonality, these two independent antenna elements are highly self-isolated and free of additional decoupling components, even though they are assembled at the same location and within the same space. Thus, the proposed antenna is attractive in 5G MIMO systems. Furthermore, the proposed co-located and space-shared MIMO antenna module was employed in a 5G smartphone to verify their radiation and diversity performances. A 12 × 12 MIMO antenna system was simulated and fabricated using the proposed module. Based on the results, the proposed module can be employed in large-scale MIMO antenna systems for current and future terminal devices owing to its high integration, compactness, simple implementation, and inherent isolation.

A Channel Estimation Method by Orthogonalizing of the time domain training signals in MIMO-OFDM systems (MIMO-OFDM 시스템에서 시간영역 훈련신호들의 직교화를 통한채널추정 방법)

  • Jeon, Hyoung-Goo
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.17 no.12
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    • pp.2818-2825
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    • 2013
  • In this paper, a channel estimation method by orthogonalizing of the time domain training signal in MIMO-OFDM systems is proposed. It has shown that Jeon's method[8] cannot be directly used in 4 Tx antenna MIMO-OFDM systems since the delayed Rx signals interfere the orthogonal property of the time domain training signals. As a possible solution to the problem, in this paper, a guard interval is inserted into the center of the training signals so that the orthogonal property between the Rx training signals can be maintained. It is shown by using computer simulations that the proposed method can estimate the channel response in time domain in 4 Tx antenna MIMO-OFDM systems.

Channel Estimation Scheme Using Modified ICA in MIMO-OFDM Systems (MIMO-OFDM 시스템에서 Modified ICA를 이용한 채널 추정 기법)

  • Kim Jong-Deuk;Byun Youn-Shik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.5A
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    • pp.475-483
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    • 2006
  • If channel coefficients errors exist in MIMO-OFDM systems, the performance degradation of systems will occurs. In order to improve the performance of MIMO-OFDM systems, the technique of obtaining accurate channel estimation in multipath fading channel is necessary. In this paper, we introduce and propose new channel estimation-modified ICA algorithm. Simulation results shows from BER and SER curves which compare the proposed algorithm under time-varying Rayleigh fading with perfect known channel. The result of channel estimation by the proposed algorithm in this simulation, it shows that PDF(amplitude of channel) are close to the case with perfect known channel at the receiver with respect to uncoded QPSK/16-QAM/64-QAM modulation. Also, we can see that BER and SER curves are very close to the case with perfect known channel. Therefore, we see that the proposed algorithm have a good performance in MIMO-OFDM systems.

Spatial Coding using Data Information and Antenna Selection Technique in MIMO System (MIMO 시스템에서 데이터 정보와 안테나 선택 기법을 이용한 공간 부호화)

  • Song, Jae-Woong;Kim, Back-Hyun;Jeong, Rag-Gyo;Kwak, Kyung-Sup
    • The Journal of The Korea Institute of Intelligent Transport Systems
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    • v.11 no.6
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    • pp.81-88
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    • 2012
  • Space diversity and space multiplexing gain can be achieved with MIMO system. This paper proposes spatial coding method to MIMO system using data information and antenna selection technique. This technique provides coding gain as well as space diversity gain. For MIMO system with BPSK modulation, BER performance is analyzed and space diversity gains are compared through simulation in terms of data maldistribution degree.

Iterative Channel Estimation Algorithm for Anti-jamming in MIMO Communication Systems (MIMO 통신 시스템에서 항재밍을 위한 반복적인 채널 추정 알고리즘)

  • Jung, Jun Hee;Hwang, Yu Min;Cha, Kyung Hyun;Lee, Jae Seang;Shin, Yoan;Kim, Jin Young
    • Journal of Satellite, Information and Communications
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    • v.11 no.3
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    • pp.32-36
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    • 2016
  • In wireless communication systems, jamming attack is a critical threat. Especially, reactive jamming can jam when the sender and receiver are communicating, which can maximize the attack efficiency of jamming. In this paper, we use the property of multi-input multi-output (MIMO) technology to achieve jamming resilient orthogonal frequency-division multiplexing (OFDM) communications. In particular, we use MIMO interference cancellation to remove the jamming signals strategically. We first investigate the reactive jamming attack model and their impacts on the MIMO-OFDM systems. We then present an iterative channel estimation algorithm that exploits MIMO interference cancellation. Our simulations show various anti-jamming methods and demonstrate the efficiency of our proposed algorithm under the reactive jamming attack.