• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.1
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• pp.48-52
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• 2017

This paper proposes a hybrid algorithm of space-time block coding and space-frequency block coding using alternate time switch. The traditional alternate time-switched space-time or space-frequency block coding technique for orthogonal frequency division multiplexing system does not provide a good performance with a variety of communication environments. This hybrid algorithm has searched good performance ranges in various environments in view points of mobile speed and doppler frequency. In this paper, we investigate better performance ranges for two algorithms, suggest a hybrid algorithm for dynamically changing communication environments, propose a structure for transmitter and receiver, and show that its performance is better than the traditional algorithm by simulations.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.6A
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• pp.640-650
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• 2004

Channel estimation schemes are proposed for Multiple Input-Multiple output Orthogonal Frequency Division Multiplexing(MIMO-OFDM) systems based on the physical layer specification of the IEEE 802.1 la. By combining the space-time block coding(STBC)/ space-frequency block coding(SFBC) techniques with the transform domain interpolation, the proposed algorithms achieve more accurate channel coefficients for the MIMO channels such that improve the BER performance. The performance improvements of the proposed algorithms are evaluated by simulations under the various multipath fading channel environments and various transmission rates.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2C
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• pp.206-212
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• 2004

In this paper, we propose a STF(Space-Time-Frequency) coded OFDM(Orthogonal Frequency Division Multiplexing) transmission scheme as an attractive solution for high bit rate data transmission in a multipath fading environment. STBC(Space-Time Block Coding) has been proposed as a simple diversity scheme using two transmit antennas. Also ST-OFDM(Space-Time Block Coded OFDM) and SF-OFDM(Space-Frequency Block Coded OFDM) transmission scheme, that the STBC is applied to the OFDM, has been proposed. In this paper, we propose STF-OFDM transmission scheme that to coded in time, space and frequency domain. The STF-OFDM transmission scheme that we propose in this paper is the way to improve a performance of conventional ST-OFDM, by using frequency diversity.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.2
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• pp.136-141
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• 2016

This paper proposes an alternate time-switched multiplexed space-time block coding technique for orthogonal frequency division modulation systems. The traditional multiplexed space-time block coding technique can provide more data rate owing to multiple transmit and receive technique, which causes a lot of hardware burden. Alternate time-switched scheme of transmitting time-domain zeros can reduce this hardware burden by half with time-domain switches only. Simulation results show that alternate time-switched scheme has almost same performance with half of baseband and RF modules in comparison with a multiplexed space-time block coding for orthogonal frequency division modulation systems with twice repetitive transmission.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.61 no.4
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• pp.234-238
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• 2012

This paper proposes a multiplexed space-frequency block coding (SFBC) technique for single-carrier modulation with frequency domain equalization. Multiplexed space-frequency block coding technique for single-carrier modulation uses multiple groups of two transmitters and suppresses the interference signals of other SFBC groups at the receiver. In this paper, we reconfigure transmit signals to adapt them for multiplexed SFBC for single-carrier modulation with frequency domain equalization and receiver structures and propose a structure for transmitter and receiver, show its performance is better than the traditional algorithm by simulations.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.65 no.4
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• pp.316-320
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• 2016

This paper proposes an alternate time-switched multiplexed space-frequency block coding technique for single-carrier modulation with frequency domain equalization. The traditional multiplexed space-frequency block coding technique for single-carrier modulation uses multiple groups of two transmitters and suppresses the interference signals of other SFBC groups at the receiver. In this paper, we reconfigure transmit signals to adapt them for alternate time-switched multiplexed SFBC for single-carrier modulation with frequency domain equalization and receiver structures and propose a structure for transmitter and receiver, show that its performance is better than the traditional algorithm by simulations.

• 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.

• The Journal of the Korea Contents Association
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• v.8 no.4
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• pp.55-62
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• 2008

Adaptive modulation and Coding(AMC) scheme is promising technique to support the demands for high data rates and wideband proposed for 4G mobile communication system standards. In this paper, adaptive modulation and coding(AMC) based on OFDM system is analyzed through simulation for single user case and compared with SISO-OFDM and SFBC(Space frequency block coding)-OFDM. The performance analysis in terms of capacity for downlink system environments with different values of constellation size under multipath fading channel is done. The adaptive modulation and coding technique is based on perfect estimation channel. It has been observed that SFBC(Space-frequency block coding)-OFDM system gives better performance in terms of capacity.

• 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.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.7
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• pp.165-168
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• 2015

In this paper, we analyze a SFBC-OFDM(Space Frequency Block Code-Orthogonal Frequency Division Multiplexing) system with antenna selection method using pilot symbols. An antenna selection criterion is based on channel coefficients estimated from pilot symbols. At each frequency, the channel coefficients is arranged and the best is selected, and then data is sent to those antenna with the best coefficients. Also, The coding and diversity gain of the proposed system are analyzed.