• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.3 s.333
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• pp.15-18
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• 2005

Multiple space-time codes (M-STTC) is composed of several space-time codes. That provides high transmission rate as well as diversity and coding gain without bandwidth expansion. In this paper, the layered receiver structures employing whitening process for M-STTC is proposed. The proposed receiver is composed of the decoding order decision block and the layered detection block. The whitening process in the latter is utilized to maximize the receive diversity gain in the layered detection. The layered receiver employing whitening process has more diversity gain and advantage of the required number of receive antenna over the layered detection with MMSE nulling. The proposed scheme achieves a 5dB gain compared to the coded layered space-time processing at the FER of $10^{-2}$.

• Journal of Communications and Networks
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• v.7 no.3
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• pp.307-312
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• 2005

In this work, we study the performance of a serial concatenated scheme comprising a convolutional code (CC) and an orthogonal space-time block code (STBC) separated by an inter-leaver. Specifically, we derive performance bounds for this concatenated scheme, clearly quantify the impact of using a CC in conjunction with a STBC, and compare that to using a STBC code only. Furthermore, we examine the impact of performing antenna selection at the receiver on the diversity order and coding gain of the system. In performing antenna selection, we adopt a selection criterion that is based on maximizing the instantaneous signal-to­noise ratio (SNR) at the receiver. That is, we select a subset of the available receive antennas that maximizes the received SNR. Two channel models are considered in this study: Fast fading and quasi-static fading. For both cases, our analyses show that substantial coding gains can be achieved, which is confirmed through Monte-Carlo simulations. We demonstrate that the spatial diversity is maintained for all cases, whereas the coding gain deteriorates by no more than $10\;log_{10}$ (M / L) dB, all relative to the full complexity multiple-input multiple-output (MIMO) system.

• 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.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.4
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• pp.70-76
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• 2009

In this paper, we propose the design criteria of the pre-processing scheme used in ABAB type quasi-orthogonal space-time block code(QOSTBC) and derive. The proposed design criteria show how to obtain full-diversity and full-rate (FDFR) property, single-symbol decodability, and increased coding gam. We design an improved ABAB type QOSTBC using the proposed design criteria. The desinged QOSTBC has a superior performance to Dalton's QOSTBC and inherits the merits of Dalton's QOSTBC, which are FDFR property, and single symbol decodability for PAM signal constellation.

• Proceedings of the IEEK Conference
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• 2008.06a
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• pp.16-17
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• 2008

본 논문은 다중 안테나 시스템에서 두 심볼을 묶어서 전송함으로써 최대 전송률을 유지하는 준직교 시공간 블록 부호(QOSTBC : quasi orthogonal space time block codes)의 성능을 평가하였다. 이제까지 제안된 여러 QOSTBC 부호는 다차원 신호 공간에서의 신호 설계 방식에 차이가 있고 결과적으로 diversity 차수는 동일하지만 부호 이득에 차이를 보인다. 채널 부호기를 결합한 경우와 그렇지 않은 경우에 여러 가지 방식의 QOSTBC의 성능을 모의실험으로 평가하였다.

• ETRI Journal
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• v.26 no.6
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• pp.622-634
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• 2004

In this paper, we discuss the design problem and the robustness of space-frequency trellis codes (SFTCs) for multiple input multiple output, orthogonal frequency division multiplexing (MIMO-OFDM) systems. We find that the channel constructed by the consecutive subcarriers of an OFDM block is a correlated fading channel with the regular correlation function of the number and time delay of the multipaths. By introducing the first-order auto-regressive model, we decompose the correlated fading channel into two independent components: a slow fading channel and a fast fading channel. Therefore, the design problem of SFTCs is converted into the joint design in both slow fading and fast fading channels. We present an improved design criterion for SFTCs. We also show that the SFTCs designed according to our criterion are robust against the multipath time delays. Simulation results are provided to confirm our theoretic analysis.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.5C
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• pp.506-513
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• 2003

Most existing space-time coding (STC) schemes have been developed for flat fading channels. To obtain antenna diversity gain, they rely on channel state information (CSI) required at the receiver through channel estimation techniques. This paper proposes a new decision feedback decoding scheme for Alamouti-based space-time block coding (STBC) transmission over time-selective fading channels. In wireless channels, time-selective fading effects arise mainly due to Doppler shift and carrier frequency offset, Modelling the time-selective fading channels as the first-order Gauss-Markov processes, we use recursive algorithms such as Kalman filtering, LMS and RLS algorithms for channel tracking. The proposed scheme consists of the symbol decoding stage and channel tracking algorithms. Computer simulations confirm that the proposed scheme shows the better performance and robustness to time-selectivity.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.7 s.349
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• pp.132-142
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• 2006

In this paper, we present a candidate high data rate space time coded OFDM system for short range personal networking. The system transmits the complex space time coded signals with a hybrid orthogonal frequency division multiplexing (OFDM) based on ultra wideband (UWB) pulses. The transmitted signals are sparse pulse trains modulated by a frequency selected from a properly designed set of frequencies. Additionally, a widely linear (WL) receive filter and a space time frequency transmission are designed by using two simple parallel linear detectors. To overcome the deeply fade in the propagation system, a beamforming combined with space time block codes also 따 e briefly discussed.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.10a
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• pp.611-614
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• 2012

Space-Time Block Code (STBC) is a simple transmit diversity scheme mitigating detrimental effects of fading channel. However, STBC receivers require channel knowledge and suffer from inaccurate channel estimation. Differential Space-Time Modulation (DSTM) renders the receiver a choice of coherent detection or non-coherent detection, depending on the availability of the channel information. Based on the simulated BER performances of these two schemes over various normalized Doppler frequency scenarios using LTE-like parameters, a benefit of adaptively switching the receiver type is investigated.

• Journal of information and communication convergence engineering
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• v.6 no.3
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• pp.261-265
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• 2008

This work presents a simplified efficient blind detection algorithm for orthogonal space-time codes(OSTBC). First, the proposed decoder exploits a proper decomposition approach of the upper triangular matrix R, which resulted from Cholesky-factorization of the composition channel matrix, to form an easy-to-solve blind detection equation. Secondly, in order to avoid suffering from the high computational load, the proposed decoder applies a sub-optimal QR-based decoder. Computer simulation results verify that the proposed decoder allows to significantly reduce computational complexity while still satisfying the bit-error-rate(BER) performance.