• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.18 no.4 s.119
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• pp.440-447
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• 2007

The switched diversity, although its performance is a little inferior to the selection diversity, is widely used due to its advantage that only one RF circuit is required for its operation without respect to the number of antennas in use. In this paper, we propose an application of the antenna switched diversity to a spread spectrum system with adaptive modulation and derived the optimal antenna switching threshold to maximize the average transmission bit rate. We also compared the performances of the proposed system with those of the two cases using a single antenna and the selection diversity with two antennas in terms of the average number of bits per symbol(BPS), the probability of no transmission, and the average BER. The performance analysis shows that, if the number of paths in a multipath channel environment increases, the performance of the proposed scheme becomes closer to that of the selection diversity based system in terms of the average BPS. Furthermore, the proposed scheme produces as almost high the probability of no transmission as the selection diversity based system for the case of low average SNR, although the former yields a little higher probability of no transmission than the latter fer the case of high average SNR.

• Journal of electromagnetic engineering and science
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• v.6 no.4
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• pp.222-228
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• 2006

In this paper, the performance of a multiuser diversity system combined with a multi-element transmit antenna system is analyzed under the assumption of independent Rayleigh fading. A measure of system .level performance is an average channel capacity as a function of the number of users and antennas. Average channel capacity is obtained from the instantaneous signal-to-noise ratio(SNR) distribution combined by both transmit diversity(TD) at each link and multiuser diversity at system level. Numerical results show that closed-loop antenna techniques provide an additional gain with multiuser diversity system due to array gain, even though space diversity gain reduces multiuser diversity gain. On the other hand, the space-time block coding(STBC) that provides full order space diversity gain only has a destructive influence on multiuser diversity.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.7A
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• pp.720-726
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• 2008

In this paper, we propose a multi-cell cooperation method for broadcast packet data services in the orthogonal frequency division multiplexing (OFDM)-based cellular system with multiple transmit antennas. In the proposed method, to transmit two streams of spatially demultiplexed or transmit diversity coded symbols over a number of transmit antennas, we divide a coded packet into multiple subparts to which different cell groups and antenna pairs are assigned. The proposed method enhances the diversity order by transforming the channel frequency responses of two symbol streams in each subpart of the broadcast packet. The increase in diversity of the proposed method is shown with the outage probability under various configurations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.8C
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• pp.762-768
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• 2005

This paper proposes new space-time block codes achieving full rate and full diversity for QAM and quasi-static Rayleigh fading channels when using any number of transmit antennas larger than 3 transmit antennas. These codes are constructed by serially concatenating the constellation rotating $precoders^{[4,5]}$ with the Alamouti scheme$3^{[3]}$ Bike the conventional A-ST-CR code$^{[6,7]}$. Computer simulations show that the proposed codes achieve approximately 1.3dB, 1.4dB and 1.5dB larger coding gains than the ST-CR $codes^{[4,5]}$ for QPSK with 3, 4 and 5 transmit antennas, respectively, and about 3dB for 16QAM with 3 transmit antennas.

• ETRI Journal
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• v.44 no.1
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• pp.117-124
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• 2022

In this paper, the performance of precoding-aided differential spatial modulation (PDSM) systems with optimal transmit antenna subset (TAS) selection is examined analytically. The average bit error rate (ABER) performance of the optimal TAS selection-based PDSM systems using a zero-forcing (ZF) precoder is evaluated using theoretical upper bound and Monte Carlo simulations. Simulation results validate the analysis and demonstrate a performance penalty < 2.6 dB compared with precoding-aided spatial modulation (PSM) with optimal TAS selection. The performance analysis reveals a transmit diversity gain of (N_T-N_R+1) for the ZF-based PDSM (ZF-PDSM) systems that employ TAS selection with N_T transmit antennas, N_S selected transmit antennas, and N_R receive antennas. It is also shown that reducing the number of activated transmit antennas via optimal TAS selection in the ZF-PDSM systems degrades ABER performance. In addition, the impacts of channel estimation errors on the performance of the ZF-PDSM system with TAS selection are evaluated, and the performance of this system is compared with that of ZF-based PSM with TAS selection.

• 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.

• Journal of information and communication convergence engineering
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• v.2 no.2
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• pp.67-70
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• 2004

In this paper, we propose two novel high-rate high-performance space-time codes for multiple-input multiple-output (MIMO) systems. When $n_T$ transmit antennas and When $n_R$ ＝ When $n_T$ receive antennas are deployed, the two proposed codes respectively offer transmission rates of (When $n_T$ -1) and (When $n_T$ -2) symbols per channel use and diversity orders of 3 and 5. As a consequence, our proposed codes allow the MIMO systems to employ a simple detection technique based on QR decomposition. Moreover, for equal or even higher spectral efficiencies, our proposed codes always provide much better bit error rate (BER) performances than V-BLAST architecture does when When $n_R$ ＝ When $n_T$. Computer simulation is given to verify performances of our proposed codes.

• Journal of electromagnetic engineering and science
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• v.12 no.4
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• pp.287-289
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• 2012

This paper proposes an alternate time-switched space-frequency block coding transmission technique for orthogonal frequency division modulation systems. There are two antennas in the transmitter but it still has only a baseband and RF and a switch that alternates between the antennas at every symbol timing. Alternating transmit symbols result in zeros that make maximal ratio receive combining possible in the receiver. Simulation results show that it provides better performance than the traditional algorithm at the expense of one additional antenna.

• Proceedings of the IEEK Conference
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• 2002.06a
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• pp.41-44
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• 2002

Alamouti proposes a two branch transmit diver-sity scheme that provides the same diversity order as maximal ratio combining at the receiver. It has many advantages of no bandwidth expansion, not requiring channel information at the transmitter and simple maximum likelihood decoding at the receiver. Papadias and Foschini extend this sch-eme to four transmit antennas and suggest several schemes to decrease the interference component and allow the attainment of the open-loop capacity. This paper shows the performance of ZF and MM-SE schemes comparing with ideal case on 4xl sy-stem over BER and 10% outage capacity.

• Journal of information and communication convergence engineering
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• v.8 no.5
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• pp.498-501
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• 2010

In this paper, we extend ultra-wideband (UWB) single input single output (SISO) systems with a hybrid pulse amplitude and position modulation (PAPM) to single input multiple output (SIMO) systems using receive antenna diversity. The performance of a rake receive diversity combining scheme for UWB SIMO systems with a PAPM is examined in a log-normal multipath fading channel and also compared with that of a time-switched transmit diversity (TSTD) multiple input single output (MISO) system. It is seen that as the number of receive antennas increases, the receive diversity combining system improves the error performance. It is shown that the TSTD UWB MISO systems offer the performance equivalent to the receive diversity combining scheme for SIMO systems.