• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4A
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• pp.282-287
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• 2005

The space time block code(STBC) can not provide simultaneously both full diversity and full transmission rate in a transmit diversity system having more than two transmit antennas.. There are a quasi orthogonal STBC for four transmit antennas that provides full transmission rate and minimized interference. Recently, a simple correlation canceling algorithm is introduced to achieve full diversity from STBC considering four transmit antennas. In this paper, we propose a new decoding procedure using the power allocation at the transmitter and subtraction interference process at the receiver to achieve a better performance without noise enhancement.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.10
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• pp.2411-2429
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• 2013

In this paper, we extend the case of information exchange error mitigation for the distributed orthogonal space-time block code (DOSTBC) for two transmit antennas to distributed quasi-orthogonal space-time block code (DQOSTBC) for four transmit antennas. A rate 1 full-diversity DQOSTBC for four transmit antennas is designed. The code matrix changes according to different information exchange error cases, so full diversity is maintained even if not all information exchange is correct. We also perform analysis of the pairwise error probability. The performance analysis indicates that the proposed rate 1 DQOSTBC outperforms rate 1/2 DOSTBC for four transmit antennas at the same transmission rate, which is confirmed by the simulation results.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.239-242
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• 2003

Transmit diversity using STBC(Space Time Block Code) provides the same diversity gain as MRRC(Maximal Ratio Receiver Combining), when the fading channel is constant across two consecutive symbols. But, when the channel condition is changed for the two consecutive symbols, the transmit diversity using STBC does not offer good performance due to the large doppler shift. In this paper, we have proposed a interference cancellation scheme for performance enhancement in transmit diversity using STBC over time selective fading channel. Simulation results for various doppler shift rates are presented for the transmit diversity using the proposed scheme.

• ETRI Journal
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• v.26 no.5
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• pp.443-451
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• 2004

Since the publication of Alamouti's famous space-time block code, various quasi-orthogonal space-time block codes (QSTBC) for multi-input multi-output (MIMO) fading channels for more than two transmit antennas have been proposed. It has been shown that these codes cannot achieve full diversity at full rate. In this paper, we present a simple feedback scheme for rich scattering (flat Rayleigh fading) MIMO channels that improves the coding gain and diversity of a QSTBC for 2$^n$ (n=3, 4, ${\cdots}$) transmit antennas. The relevant channel state information is sent back from the receiver to the transmitter quantized to one or two bits per code block. In this way, signal transmission with an improved coding gain and diversity near to the maximum diversity order is achieved. Such high diversity can be exploited with either a maximum-likelihood receiver or low-complexity zero-forcing receiver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.5
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• pp.444-450
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• 2004

In mobile communications environment, STBC-OFDM(Space Time Block Code-Orthogonal Frequency Division Multiplexing) system with transmit diversity obtains the MRRC(Maximal Ratio Receiver Combining) diversity gain in time-invariant channel between two received symbols. But in time-variant channel, due to the interference between received symbols, MRRC diversity gain cant be obtained. So, when the mobile device with transmit diversity moves in high speed, the scheme to reduce the performance degradation due to the interference is needed. In this paper, we propose the receiver architecture with advanced transmit diversity, which improves the performance of STBC-OFDM system. The proposed architecture obtains the diversity gain without the change of transmit bandwidth at the receiver with the interference canceller using ZF(Zero Forcing) algorithm. Simulation results show performance improvement as doppler shift is increasing.

• Journal of IKEEE
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• v.11 no.4
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• pp.340-347
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• 2007

This paper proposes a new class of Space-Time Block Codes, which is manipulated from the existing transmit diversity schemes. We analyze the performance and the receiver complexity of the proposed scheme and confirm that the new diversity scheme can yield performance gain over other existing four-transmit antenna cases. By relaxing the diversity criterion on code designs, the proposed space-time code provides a full transmission rate for four-transmit antennas and makes it possible to approach the open-loop Shannon channel capacity. Outage capacity and simulation results are used to show that substantial improvements in performance while maintaining a simple linear processing receiver structure are obtained in frequency selective channels.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.85-88
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• 2005

Space-time code is a good solution to get transmit diversity. During the last years a number of space-time block codes have been proposed for use in multiple transmit antenna systems. This code, however, was presented only for the special case of the certain numbers of transmit antennas and the certain modulation schemes. and designed under the assumption that the transmitter has no knowledge about the channel. In this work, on the other hand, we consider the case when the transmitter has partial, but not perfect knowledge about the channel. This system can have full diversity for arbitrary number of the transmit antennas with a little bits of feedback.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.6A
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• pp.556-562
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• 2006

In this paper, macro diversity coding methods are proposed to efficiently transmit broadcast packet data over mobile cellular networks based on OFDM. In the method, cells are divided into multiple cell groups which transmit one of two orthogonal branches in a transmit diversity code. Furthermore, a coded packet is partitioned into the subblocks for which different cell group combinations are assigned to transmit two different branches. The methods extend the cell coverage at the same transmit power due to the transmit diversity of each symbol and coding diversity obtained through different fading statistics over the subblocks.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.7B
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• pp.695-705
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• 2002

In this paper, we propose a simple open loop transmit diversity (TD) scheme for the wideband code division multiple access (W-CDMA) systems in Rician multipath fading channels such as rural area or satellite channels where line-of-sight (LOS) paths are in presence. The proposed scheme does not require any pre-processing of transmit data, resulting in simpler structure as compared to conventional closed loop transmit adaptive array (TxAA) and open loop space-time transmit diversity (STTD). We analytically derive the probability density function of signal-to-noise ratio at the Rake receiver output and the uncoded bit error rate performance of the proposed scheme. Extensive simulation is Performed to verify the analytical performance of the proposed scheme under typical Rician multipath fading channel environments. Moreover, comparative results with the conventional TxAA and STTD are also provided. Simulation results show that the proposed scheme shows slightly better performance than the conventional open loop STTD under the channels with very weak LOS components, however, it significantly outperforms the STTD under the channels with dominant LOS components, and achieves a close performance of ideal closed loop TxAA.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.12A
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• pp.1219-1225
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• 2007

In this paper, we propose a new quasi-orthogonal space-time block code(QO-STBC) achieving full rate and full diversity for general QAM and quasi-static Rayleigh fading channels with four transmit antennas. This code possesses the quasi orthogonal property like the conventional minimum decoding complexity QO-STBC(MDC-QO-STBC), which allows independently a maximum likelihood(ML) decoding to only require joint detection of two real symbols. By computer simulation results, we show that the proposed code exhibits the identical BER performance with the existing MDC-QO-STBC. However, the proposed code has an advantage in the transceiver implementation since the original coding scheme may be modified so that increases of peak-to-average power ratio occur at only two transmit antennas, but the MDC-QO-STBC does at all of transmit antennas.