• The Journal of Korean Institute of Communications and Information Sciences
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• v.32 no.2A
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• pp.195-202
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• 2007

A differential space-frequency block code - orthogonal frequency division multiplexing (SFBC-OFDM) scheme as a multiple-input multiple-output (MIMO) transmission technique for next-generation digital multimedia broadcasting (DMB) is proposed in this paper. A linear decoding method for differential SFBC, which performs comparably to the ML decoding method, is derived for the cases of two or four transmit antennas. A simple table lookup method is proposed to improve the efficiency of the encoding/decoding process of DSFBC for the case of non-constant modulus constellations. A DMB MIMO channel model, developed by extending the 3GPP MIMO model to fit DMB environments, is used to compare BER performances of differential space block code schemes for various channel environments. Simulation results show that the differential SFBC-16QAM scheme using either four transmit antennas with one receive antenna or two transmit antennas with two receive antennas achieves a performance gain of 12dB than that of the conventional DQPSK scheme, even with a data rate twice faster.

• Journal of Communications and Networks
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• v.5 no.2
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• pp.167-173
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• 2003

We treat the problem of channel estimation and interference cancellation in multiuser ultra-wide-band (UWB) communication systems over multipath fading channels. The UWB system under consideration employs a random time-hopping impulse radio format. We develop a channel estimation method based on linear weighted algorithm. An iterative channel estimation and interference cancellation scheme is proposed to successively improve the receiver performance. We also consider systems employing multiple transmit and/or receive antennas. For systems with multiple receive antennas, we develop a diversity receiver for the wellseparated antennas. For systems with multiple transmit antennas, we propose to make use of Alamouti’s space-time transmission scheme, and develop the corresponding channel estimation and interference cancellation receiver techniques. Simulation results are provided to demonstrate the performance of various UWB receiver techniques developed in this paper.

• Proceedings of the IEEK Conference
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• summer
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• pp.302-309
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• 2004

The transmission capacity of wireless communication systems may become dramatically high by employ multiple transmit and receive antennas with space-time coding techniques appropriate to multiple transmit antennas. For large number of transmit antennas and at high bandwidth efficiencies, the receiver may become too complex whenever correlation across transmit antennas is introduced. Reducing decoding complexity at receiver by combining array processing and space-time codes (STC) helps a communication system using STC to overcome the big obstacle that prevents it from achieving a desired high transmission rate. Multi-carrier CDMA (MC-CDMA) allows providing good performance in a channel with high inter-symbol interference. Antenna array, STC and MC-CDMA system have a similar characteristic that transmit-receive data streams are divided into sub-streams. Thus, there may be a noticeable reduction of receiver complexity when we combine them together. In this paper, the combination of array processing and STC in MC-CDMA system over slow selective-fading channel is investigated and compared with corresponding existing MC-CDMA system using STC. A refinement of this basic structure leads to a system design principle in which we have to make a trade off between transmission rate, decoding complexity, and length of spreading code to reach a given desired design goal.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.12 no.7
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• pp.1271-1277
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• 2008

This paper proposes the code acquisition scheme on a MIMO channel for preamble search in a CDMA-MIMO uplink system. The multiple transmit/receive antennas are used for beamforming. The performance of a ML code acquisition technique based on transmit and receive beamforming is analyzed by considering rho detection probability. The acquisition performance and MAT for a MIMO code acquisition system are numerically evaluated. It is shown that multiple transmit antennas can give the code acquisition system a transmit beamforming gain and result in much better performance than a SIMO case.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.11
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• pp.3026-3045
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• 2012

In this paper, diversity-multiplexing tradeoff (DMT) of three-user wireless multiple-antenna cooperative systems is investigated in general fading channels when half-duplex and decode-and-forward relay is employed. Three protocols, i.e., adaptive protocol, receive diversity protocol, and dual-hop relaying protocol, are considered. The general fading channels may include transmit and/or receive correlation and nonzero channel means, and are extensions of independent and identically distributed Rayleigh or Rician fading channels. Firstly, simple DMT expressions are derived for general fading channels with zero channel means and no correlation when users employ arbitrary number of antennas. Explicit DMT expressions are also obtained when all users employ the same number of antennas and the channels between any two users are of the same fading statistics. Finally, the impact of nonzero channel means and/or correlation on DMT is evaluated. It is revealed theoretically that the DMTs depend on the number of antennas at each user, channel means (except for Rayleigh and Rician fading statistics), transmit and/or receive correlation, and the polynomial behavior near zero of the channel gain probability density function. Examples are also provided to illustrate the analysis and results.

• 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.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.3
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• pp.507-513
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• 2015

In this paper, we present the bit-error rate (BER) performance of quasi-orthogonal space-time block code (QOSTBC) massive multiple-input multiple-output (MIMO) system employing up to 32 transmit and receive antennas. The QOSTBC, due to its advantages in transmission rate and decoding complexity, is an important transmit diversity scheme for more than 2 transmit antennas. As massive MIMO implies very large number of antennas, practically at least more than 15 antennas, a different number of transmit and receive antennas (i.e. $2{\times}2$, $4{\times}4$, $8{\times}8$, $16{\times}16$ and $32{\times}32$) using QOSTBC for the massive MIMO system are considered. The BER performance of the massive MIMO with antennas up to $32{\times}32$ using BPSK modulation scheme is analyzed. Simulation results show that the full-rate massive MIMO systems with QOSTBC give a significant performance improvement due to increasing diversity effect, compared with previously considered massive MIMO systems.

• Journal of the Korea Society of Computer and Information
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• v.13 no.1
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• pp.135-141
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• 2008

The utilization techniques for multiple transmit and receive antennas or high capacity modulation schemes are essential to cope with the rapidly increasing demand for realizing more diverse wireless communication services with high rates. However, employing multiple receive antennas at the mobile units seems less practical due at the size and power limitations. Therefore, transmit diversify techniques have been extensively investigated for the downlink transmission to improve the performance In order to overcome the above mentioned problems, we construct a simulation model which combines STC and polarization diversity which scheme is requiring less cost to realize. Multi-level quadrature amplitude modulation (MQAM) is an attractive modulation scheme for wireless communication due to the high spectral efficiency it provides. Thus, the performance for our scheme is presented when 16QAM modulation techniques are applied. and compared with the former schemes.

• Journal of Broadcast Engineering
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• v.9 no.1
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• pp.32-42
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• 2004

In this paper we apply space-time block code with multiple transmitter/receiver antennas to the Advanced Television Systems Committee (ATSC) terrestrial broadcasting systems. Especially, we apply Aiamouti scheme with two transmitter antennas and multiple receiver antennas to the ATSC broadcasting system. Also. diversity technique with multiple receiver antennas and space-time block code scheme with multiple transmitter/receiver antennas are compared. Our simulation results show that the ATSC broadcasting system with multiple transmitter/receiver antennas has an extremely good performance than the scheme with single transmitter/receiver antenna in the Rayleigh fading channel.

• Journal of information and communication convergence engineering
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• v.9 no.6
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• pp.652-656
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• 2011

In this paper, a transmitter-based multipath processing and inter-channel interference (ICI) cancellation scheme for a ultra-wideband (UWB) spatial multiplexing (SM) multiple input multiple output (MIMO) system is presented. It consists of taps delayed lines and zero-forcing (ZF) filters in the transmitter and correlators in the receiver. For a UWB SM MIMO system with N transmit antennas, M receive antennas, and Q resolvable multipath components, the BER performance of a linear transmit ZF scheme is analyzed in a log-normal fading channel and also compared with that of a receiver-based ICI rejection approach. It is found that when M ${\leq}$ N, the transmit ZF processing approach outperforms the ZF receiver while making the mobile units low-cost and low-power.