• Title/Summary/Keyword: input-output matrix

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Lattice-Reduction-Aided Detection based Extended Noise Variance Matrix using Semidefinite Relaxation in MIMO Systems (MIMO시스템에서 Semidefinite Relaxation을 이용한 잡음 분산 행렬 기반의 Lattice-Reduction-Aided 검출기)

  • Lee, Dong-Jin;Park, Su-Bin;Byun, Youn-Shik
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.11C
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    • pp.932-939
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    • 2008
  • Recently lattice-reduction (LR) has been used in signal detection for multiple-input multiple-output (MIMO) systems. The conventional LR aided detection schemes are combinations of LR and signal detection methods such as zero-forcing (ZF) and minimum mean square error (MMSE) detection. In this paper, we propose the Lattice-Reduction-aided scheme based on extended noise variance matrix to search good candidate symbol set in quantization step. Then this scheme estimates transmitted symbol with Semidefinite Relaxation by candidate symbol set. Simulation results in a random MIMO system show that the proposed scheme exhibits improved performance and a slight increase in complexity.

A Channel State Information Feedback Method for Massive MIMO-OFDM

  • Kudo, Riichi;Armour, Simon M.D.;McGeehan, Joe P.;Mizoguchi, Masato
    • Journal of Communications and Networks
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    • v.15 no.4
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    • pp.352-361
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    • 2013
  • Combining multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) with a massive number of transmit antennas (massive MIMO-OFDM) is an attractive way of increasing the spectrum efficiency or reducing the transmission energy per bit. The effectiveness of Massive MIMO-OFDM is strongly affected by the channel state information (CSI) estimation method used. The overheads of training frame transmission and CSI feedback decrease multiple access channel (MAC) efficiency and increase the CSI estimation cost at a user station (STA). This paper proposes a CSI estimation scheme that reduces the training frame length by using a novel pilot design and a novel unitary matrix feedback method. The proposed pilot design and unitary matrix feedback enable the access point (AP) to estimate the CSI of the signal space of all transmit antennas using a small number of training frames. Simulations in an IEEE 802.11n channel verify the attractive transmission performance of the proposed methods.

Operational modal analysis of reinforced concrete bridges using autoregressive model

  • Park, Kyeongtaek;Kim, Sehwan;Torbol, Marco
    • Smart Structures and Systems
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    • v.17 no.6
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    • pp.1017-1030
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    • 2016
  • This study focuses on the system identification of reinforced concrete bridges using vector autoregressive model (VAR). First, the time series output response from a bridge establishes the autoregressive (AR) models. AR models are one of the most accurate methods for stationary time series. Burg's algorithm estimates the autoregressive coefficients (ARCs) at p-lag by reducing the sum of the forward and the backward errors. The computed ARCs are assembled in the state system matrix and the eigen-system realization algorithm (ERA) computes: the eigenvector matrix that contains the vectors of the mode shapes, and the eigenvalue matrix that contains the associated natural frequencies. By taking advantage of the characteristic of the AR model with ERA (ARMERA), civil engineering can address problems related to damage detection. Operational modal analysis using ARMERA is applied to three experiments. One experiment is coupled with an artificial neural network algorithm and it can detect damage locations and extension. The neural network uses a specific number of ARCs as input and multiple submatrix scaling factors of the structural stiffness matrix as output to represent the damage.

Frequency Domain Properties of EALQR with Indefinite Weighting Matrix

  • Seo, Young-Bong;Park, Jae-Weon
    • Journal of Mechanical Science and Technology
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    • v.17 no.3
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    • pp.329-335
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    • 2003
  • EALQR (Linear Quadratic Regulate. design with Eigenstructure Assignment capability) has the capability of exact assignment of eigenstructure with the guaranteed margins of the LQR for MIMO (Multi-Input Multi-Output) systems. However, EALQR undergoes a restriction on the state-weighting matrix Q in LQR to be indefinite with respect to the region of allowable closedloop eigenvalues. The definiteness of the weighting matrix is closely related to the robustness property of a given system. In this paper, we derive a relation between the indefinite weighting matrix Q and the robustness property for EALQR. The modified frequency domain inequality, that could be guaranteed by EQLQR with an indefinite weighting matrix, is presented.

Design and Implementation of a Reverse Matrix Converter for Permanent Magnet Synchronous Motor Drives

  • Lee, Eunsil;Lee, Kyo-Beum
    • Journal of Electrical Engineering and Technology
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    • v.10 no.6
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    • pp.2297-2306
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    • 2015
  • This paper presents the development of a system with a reverse matrix converter (RMC) for permanent magnet synchronous motor (PMSM) drive and its effective control method. The voltage transfer ratio of the general matrix converter is restricted to a maximum value of 0.866, which is not suitable for applications whose source voltages are lower than the load voltages. The proposed RMC topology can step up the voltage without any additional components in the conventional circuit. Its control method is different from traditional matrix converter’s one, thus this paper proposes control schemes of RMC by means of controlling both the generator and motor side currents with properly designed control loop. The converter can have sinusoidal input/output current waveforms in steady state condition as well as a boosted voltage. In this paper, a hardware system with an RMC for a PMSM drive system is described. The performance of the system was investigated through experiments

Optimization of Channel Capacity in MIMO Systems

  • Pham Van-Su;Le Minh Tuan;Yoon Giwan
    • Journal of information and communication convergence engineering
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    • v.3 no.4
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    • pp.172-175
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    • 2005
  • In this paper, a new method to get the optimum channel capacity of a Multiple-Input Multiple­Output (MIMO) system is presented. The proposed method exploits the diagonal structure of channel matrix to maximize the channel capacity. The diagonal format of the channel matrix is formed by multiplying the transmitted signal with the pre-compensated channel PCC) matrix. Numerical simulations show that the proposed method exploiting the diagonal structure of channel matrix could significantly increase the system capacity compared with the system without applying the diagonal structure of channel matrix.

A New Approach to Get the Optimum Channel Capacity in MIMO Systems

  • Su, Pham-Van;Tuan, Le-Minh;Giwan Yoon
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2002.11a
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    • pp.317-319
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    • 2002
  • In this paper, a new method to get the optimum channel capacity of a Multiple-Input Multiple-Output (MIMO) system is presented. The proposed method exploits the diagonal structure o f channel matrix in order to maximize the channel capacity. The diagonal format of the channel matrix is formed by multiplying the transmitted signal with the precompensated channel (PCC) matrix. Numerical simulations show that the proposed method exploiting the diagonal structure of channel matrix could significantly increase the system capacity compared with the system without applying the diagonal structure of channel matrix.

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Covariance Matrix Synthesis Using Maximum Ratio Combining in Coherent MIMO Radar with Frequency Diversity

  • Jeon, Hyeonmu;Chung, Yongseek;Chung, Wonzoo;Kim, Jongmann;Yang, Hoongee
    • Journal of Electrical Engineering and Technology
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    • v.13 no.1
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    • pp.445-450
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    • 2018
  • Reliable detection and parameter estimation of a radar cross section(RCS) fluctuating target have been known as a difficult task. To reduce the effect of RCS fluctuation, various diversity techniques have been considered. This paper presents a new method for synthesizing a covariance matrix applicable to a coherent multi-input multi-output(MIMO) radar with frequency diversity. It is achieved by efficiently combining covariance matrices corresponding to different carrier frequencies such that the signal-to-noise ratio(SNR) in the combined covariance matrix is maximized. The value of a synthesized covariance matrix is assessed by examining the phase curves of its entries and the improvement on direction of arrival(DOA) estimation.

Blind Channel Estimation based on Hadamard Matrix Interstream Transmission for Multi-Cell MIMO Networks (다중 셀 MIMO 네트워크를 위한 Hadamard 행렬 Interstream 전송 기반 Blind 채널 추정)

  • Yang, Jae-Seung;Hanif, Mohammad Abu;Park, Ju-Yong;Lee, Moon-Ho
    • The Journal of the Institute of Internet, Broadcasting and Communication
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    • v.15 no.4
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    • pp.119-125
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    • 2015
  • In this paper, we introduce a Hadamard matrix interstream transmission based blind channel estimation for multi-cells multiple-input and multiple-output (MIMO) networks. The proposed scheme is based on a network with mobile stations (MS) which are deployed with multi cells. We assume that the MS have the signals from both cells. The signal from near cell are considered as desired signal and the signals from the other cells are interference signal. Since the channel is blind, so that we transmit Hadamard matrix pattern pilot stream to estimate the channel; that gives easier and fast channel estimation for large scale MIMO channel. The computation of Hadamard based system takes only complex additions, and thus the complexity of which is much lower than the scheme with Fourier transform since complex multiplications are not needed. The numerical analysis will give perfection of proposed channel estimation.

Efficient Implementation of a Pseudorandom Sequence Generator for High-Speed Data Communications

  • Hwang, Soo-Yun;Park, Gi-Yoon;Kim, Dae-Ho;Jhang, Kyoung-Son
    • ETRI Journal
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    • v.32 no.2
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    • pp.222-229
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    • 2010
  • A conventional pseudorandom sequence generator creates only 1 bit of data per clock cycle. Therefore, it may cause a delay in data communications. In this paper, we propose an efficient implementation method for a pseudorandom sequence generator with parallel outputs. By virtue of the simple matrix multiplications, we derive a well-organized recursive formula and realize a pseudorandom sequence generator with multiple outputs. Experimental results show that, although the total area of the proposed scheme is 3% to 13% larger than that of the existing scheme, our parallel architecture improves the throughput by 2, 4, and 6 times compared with the existing scheme based on a single output. In addition, we apply our approach to a $2{\times}2$ multiple input/multiple output (MIMO) detector targeting the 3rd Generation Partnership Project Long Term Evolution (3GPP LTE) system. Therefore, the throughput of the MIMO detector is significantly enhanced by parallel processing of data communications.