• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.32-33
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• 2013

본 논문에서는 높은 전송량을 요구하는 차세대 UHDTV(ultra-high definition television) 방송시스템을 위하여 MIMO(multi-input multi-output) 전송 기법을 고려하였다. 이러한 MIMO 전송 기법 중에서 가장 좋은 수신 성능을 나타내며, 송신 안테나 개수에 비례하여 전송량이 증가하는 LDC 전송 기법과 수신 성능 향상을 위하여 회전성상 및 심벌의 지연을 이용하는 기법을 고려하였다. 연속적인 에러가 발생하는 채널환경에서 수신 성능을 향상시키기 위해서는 신호를 분산시켜 전송하거나 신호를 섞어서 보내는 방법이 필요하다. 그러므로 본 논문에서는 이러한 두 가지 기법을 동시에 고려하여 높은 전송량을 달성하면서 수신 성능을 향상시킬 수 있는 회전성상이 적용된 LDC MIMO 전송 기법을 제안하고 수신 성능을 컴퓨터 시뮬레이션을 통하여 분석하였다.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.10
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• pp.26-33
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• 2014

The spatial correlation (SC) for a multipath environment based on a $2{\times}2$ MIMO system are computed on the observation planes in the Rayleigh/Rician fading channels inside a mode stirred chamber. The correlation coefficients were obtained and compared for different distances and orthogonal polarization between two transmit antennas. The proposed method is useful for quantifying the potential diversity gain in antenna diversity systems.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.11
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• pp.28-34
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• 2011

In CDMA-based systems, recently, researches on chip-level equalization have been studied in order to improve receiving performance when supporting high-rate data services. In this paper, we propose Griffiths' algorithm based chip-level adaptive LMMSE equalizers for HSDPA MIMO systems using D-TxAA (dual stream transmit antenna array). First, we will derive two possible structures of Griffiths' algorithm based equalizer, and then compare their performance through computer simulations in various mobile channel environments.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.4A
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• pp.384-389
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• 2004

In this paper, we investigate channel estimation techniques based on the comb-type pilot arrangement for a mobile MIMO OFDM system. Moreover, to enhance channel estimation, an efficient channel estimation technique is proposed. Simulation results show that the proposed channel estimator is accurate and effective for tracking variations of channels between multiple transmit antennas and receive antennas in time-varying radio channels.

• Journal of Satellite, Information and Communications
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• v.5 no.1
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• pp.90-93
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• 2010

This paper shows various perfermance analysis utilizing STC(Space Time Coding) in MIMO mobile communication by WiBro system environments. In this paper, 3 algorithm which are SM method, ML (Maximum Likelihood) and ZF(Zero Forcing) algorithm use for perfermance analysis. From the various simulation result, it is confirm that ZF method is superior compare than STC and ML method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.6A
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• pp.494-499
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• 2009

In this paper, we provide an efficient method of user selection for achieving the maximum system throughput in downlink multiuser Multiple-Input Multiple-Output (MIMO) systems. A proposed method is for selecting a fine user set only with powers of each user channel and angles between them. This algorithm is simpler than SUS because there is no considering about the optimal value of correlation. The proposed method finds the user set toward maximizing system throughput, so it has high performance.

• 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.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.16 no.2
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• pp.153-160
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• 2017

Recently, the demand has continued to increase for higher data rates and improved multimedia services through wireless internet access. In order to increase the data rate and link reliability, 3GPP LTE/A and IEEE 802.16e/m WiMAX systems incorporate MIMO transmission schemes. Since the hardware complexity increases with the number of transmit data streams and mobile devices have limited physical dimensions, an multiple input multiple output (MIMO) ystem with two antennas at both the transmitter and the receiver ($2{\times}2$) is considered to be a possible solution for mobile devices. In this paper, a low-complexity soft output MIMO symbol detector based on Modified-SQRD is proposed for mobile devices with two transmit and two receive antennas.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.7A
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• pp.535-544
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• 2012

Multi-Input Multi-Output (MIMO) transmission is now considered as one of essential techniques enabling high rate data transmissions in wireless communication systems. In addition, severe channel impairments in wireless systems should be compensated by using highly efficient forward error correction (FEC) codes. Turbo codes or low density parity check (LDPC) codes, using iterative decoding with soft decision detection information (SDDI), are the most common examples. The excellent performance of these codes should be conditioned on accurate estimation of SDDI from the MIMO detection process. In this paper, we propose a soft MIMO detection scheme using QR decomposition of channel matrices as an efficient means to provide accurate SDDI to the iterative decoder. The proposed method employed a two sequential soft MIMO detection process in order to reduce computational complexity. Compared to the soft ZF method calculating the direct inverse of the channel matrix, the complexity of the proposed method can be further reduced as the number of antennas is increased, without any performance degradation.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.241-244
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• 2005

In this paper, we construct UWB system formed by MIMO(Multi-input Multi-output) antennas using indoor WPAN(Wireless Personal Area Network) channel modeling and analyze the interference among these channels.