• Journal of the Institute of Electronics Engineers of Korea TC
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• v.49 no.5
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• pp.84-90
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• 2012

Since the major cellular data service providers in U.S, Japan as well as in Korea started the LTE (Long Term Evolution) service, there has been more strong need for the methods that can accurately measure the MIMO (Multi Input-Multi Outout) OTA (Over The Air) performance of LTE handsets because the performance of the MIMO antenna determines the packet data rates in the downlink and therefore the higher system throughput of the network. In this regard, there has been a lot discussions in 3GPP on the candidate MIMO OTA test solutions. In this paper, a faire comparison has been done for the conventional method, the Envelop Correlation Coefficient (ECC) measurements, and the anechoic chamber based MIMO OTA test solution, one of the candidate system being discussed in 3GPP. The evaluations and the comparisons are conducted by numerically and experimentally.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.9
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• pp.922-927
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• 2013

In this paper, we evaluate the performance of up-link multi-user MIMO systems with SM. The receiver demodulates the received signal using ML method determines the signal which seems to be the most probable after comparing the received signal and all transmitted signal candidates. When transmitting with the same data rate, the SM method shows better performance of bit error rate(BER) than that of the space shift keying(SSK) of the previously proposed multi-user system.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.2
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• pp.635-656
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• 2019

In this paper, we investigate the degrees of freedom (DoF) of a multi-cell multi-user multiple-input multiple-output (MIMO) interference broadcast channel (IBC) with non-cooperation distributed base stations (BS), where each BS serves users of its corresponding cell. When all BSs simultaneously transmit their own signals over the same frequency band in the MIMO IBC, the edge users in each cell will suffer the inter-cell interference (ICI) and inter-user interference (IUI) signals. In order to eliminate the ICI and IUI signals, a distributed space time interference alignment (DSTIA) approach is proposed where each BS has only limited access to distributed moderately-delay channel state information at the transmitter (CSIT). It is shown that the DSTIA scheme can obtain the appreciate DoF gains. In addition, the DoF upper bound is asymptotically achievable as the number of antenna at each BS increases. It is shown that the DSTIA method can get DoF gains over other interference alignment schemes with delayed CSIT in literature. Moreover, the DSTIA method can attain higher DoFs than the IA schemes with global CSIT for certain antenna configurations.

• Journal of Broadcast Engineering
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• v.16 no.2
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• pp.226-236
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• 2011

In this paper, we propose the channel estimation for the space time coded-orthogonal frequency division multiplexing (ST-OFDM) muti-input multi-output (MIMO) system with comb type pilot arrangements. In the conventional method, specially constructed pilots are inserted in the OFDM symbols at all transmit antennas separately. The proposed algorithm multiplies the orthogonal code to be transmitted OFDM symbols to estimate channels at the receiver. This algorithm can estimate a long channel delay with high accuracy. It is proved by computer simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.3A
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• pp.235-239
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• 2008

In this paper, we study a simulation model for cooperative MIMO (multiple-input multiple-output) channels and present a cooperative one-ring channel model which is extended from the geometrical one-ring and two-ring scattering models. Assuming that the source, the destination and the relay are surrounded by an infinite number of scatters, we derive a reference model for the cooperative one-ring channel and propose a simulation model based on the reference model provided in the paper. Then we show how modeling parameters of the simulation model are determined to match the correlation functions for the respective models. With numerical investigation, we also show that the correlation functions for the reference and the simulation are well matched.

• Journal of Institute of Control, Robotics and Systems
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• v.14 no.1
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• pp.42-48
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• 2008

This paper presents an observer design method for a special class of multi input multi output(MIMO) nonlinear systems. First, we characterize the class of MIMO nonlinear systems with a block triangular structure. Also, the observability matrices for SISO nonlinear systems are extended to MIMO systems. By using the generalized observability matrices, it is shown that under the boundedness conditions of system state and input, the proposed observer guarantees the local exponential stability of error dynamics. Finally, its application to induction motor is given to verify the proposed method.

• The Journal of the Korea institute of electronic communication sciences
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• v.15 no.2
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• pp.219-224
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• 2020

In this paper, we studied the compact MIMO(: Multi-Input Multi-Output) antenna for multi-beam pattern generation and control in narrow space. The characteristics and performance of the basic Dipole SPA and Monopole SPA structures are shown. We implemented a monopole SPA antenna and measured its performance in an 802.11g system. When the average transmission rate was measured using the SPA antenna, the SPA antenna improved the best performance by 8.7 times compared to commercial antenna.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 1998.06a
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• pp.194-198
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• 1998

A novel fuzzy basis function vector- based adaptive control approach for Multi-input and Multi-output(MIMO) system is presented in this paper, in which the nonlinear plants is first linearised, the fuzzy basis function vector is then introduced to adaptively learn the upper bound of the system uncertainty vector, and its output is used as the paramenters of the compensator in the sense that both the robustness and the asymptotic error convergence can be obtained for the closed loop nonlinear control system.

• Structural Engineering and Mechanics
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• v.10 no.4
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• pp.359-369
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• 2000

Random loading identification has long been a difficult problem for Multi-Input-Multi-Output (MIMO) structure. In this paper, the Pseudo Excitation Method (PEM), which is an exact and efficient method for computing the structural random response, is extended inversely to identify the excitation power spectral densities (PSD). This identified method, named the Inverse Pseudo Excitation Method (IPEM), resembles the general dynamic loading identification in the frequency domain, and can be used to identify the definite or random excitations of complex structures in a similar way. Numerical simulations are used to reveal the the difficulties in such problems, and the results of some numerical analysis are discussed, which may be very useful in the setting up and processing of experimental data so as to obtain reasonable predictions of the input loading from the selected structural responses.

• ETRI Journal
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• v.40 no.5
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• pp.582-591
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• 2018

In this paper, we present a performance analysis of large-scale multi-input multi-output (MIMO) systems for wireless backhaul networks. We focus on fully connected N nodes in a wireless meshed and multi-hop network topology. We also consider a large number of antennas at both the receiver and transmitter. We investigate the transmission schemes to support fully connected N nodes for half-duplex and full-duplex transmission, analyze the achievable ergodic sum rate among N nodes, and propose a closed-form expression of the achievable ergodic sum rate for each scheme. Furthermore, we present numerical evaluation results and compare the resuts with closed-form expressions.