• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.3 no.1 s.4
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• pp.117-125
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• 2004

Space-time coding and modulation exploit the presence of multiple transmit antennas to improve performance on multipath Rayleigh fading channels. In this paper, we propose the Trellis-Coded Differential Space Time Modulation-OFDM system with multiple symbol detection. The Trellis-code perform the set partition with unitary group codes. The Viterbi decoder containing new branch metrics is introduced in order to improve the bit error rate (BER) in the differential detection of the Unitary differential space time modulation. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency.

• Journal of Communications and Networks
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• v.4 no.2
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• pp.90-96
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• 2002

We present a family of constant-amplitude constellations of even dimensions 8 and above. These constellations allow trellis coded modulation to be implemented without the usual penalty paid for constellation expansion. The new constellations are generated by concatenating either n QPSK points or n QPSK points rotated by 45 degrees, for any n $\geq$ 4. Our constellations double the number of points available for transmission without decreasing the distance between points and without increasing the average or peak energies, introducing asymmetry, or increasing the modulation level. Effective gains of 2.65 dB with minimum complexity through 6.42 dB with moderate complexity are demonstrated using the 8D constellation.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.12C
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• pp.971-976
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• 2010

We introduce an error correcting 4/6 modulation codes for holographic data storage, and simulate under adding mis-alignment noise. The holographic data storage has two-dimensional intersymbol interference. To increase the channel performance, it is necessary to use modulation code. Furthermore, if the modulation code has trellis structure, error correcting capability is added. The error correcting 4/6 modulation code shows better performance than conventional modulation codes with and without mis-alignment noise.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.20 no.5
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• pp.895-901
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• 2016

The next generation wireless and satellite communications require high transmission efficiency and high reliability to provide various services with subscribers. To satisfied these requirements, incorporated MIMO (Multiple Input Multiple Output) system with FTN (Faster Than Nyquist) techniques based on layered space time coded method are considered in the paper. To improve performance, STTC (Space Time Trellis Code) was employed as an inner code. As the same as SISO (Single Input Single Output) system, the outer codes are turbo codes. In receiver side, BCJR algorithm is used for STTC decoding in order to eliminate interferences induced by FTN transmission. They can yield significantly increased the data rates and improved link reliability without additional bandwidth. Therefore, we proposed a new decoding model for MIMO FTN model and confirmed that performance was improved compared to conventional SISO model according to amount of interference for FTN.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.1 s.343
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• pp.89-94
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• 2006

We present a generalized version of principal ratio combining (PRC)[1], which is a near-optimum decoding scheme for space-time trellis codes in quasi-static flat fading environments. In [1], the performance penalty increases as the number of receive antennas increases. In the proposed scheme, receive antennas are divided into K groups, and the PRC decoding method is applied to each group. This shows a flexible tradeoff between performance and decoding complexity by choosing the appropriate K. Moreover, we also propose the performance index(PI) to easily predict the decoding performance among the possible different(receive antenna) configurations.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.164-167
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• 2005

Recently, STC techniques have been considered to be candidate to support multimedia services in the next generation mobile radio communications and have been developed the many communications systems in order to achieve the high data rates. In this paper, we propose the Trellis-Coded Differential Space Time Modulation system with multiple symbol detection. The Trellis-code performs the set partition with unitary group codes. The Viterbi decoder containing new branch metrics is introduced in order to improve the bit error rate (BER) in the differential detection of the unitary differential space time modulation. Also, we describe the Viterbi algorithm in order to use this branch metrics. Our study shows that such a Viterbi decoder improves BER performance without sacrificing bandwidth and power efficiency.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.5
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• pp.504-511
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• 2016

In this paper, MIMO system based on turbo equalization techniques which LDPC codes were outer code and space time trellis codes (STTC) were employed as an inner code are studied. LDPC decoder and STTC decoder are connected through the interleaving and de-interleaving that updates each other's information repeatedly. In conventional turbo equalization of MIMO system, BCJR decoder which decodes STTC coded bits required two-bit wise decoding processing. Therefore duo-binary turbo codes are optimal for MIMO system combined with STTC codes. However a LDPC decoder requires bit unit processing, because LDPC codes can't be applied to these system. Therefore this paper proposed turbo equalization for MIMO system based on LDPC codes combined with STTC codes. By the simulation results, we confirmed performance of proposed turbo equalization model was improved about 0.6dB than that of conventional LDPC codes.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7B
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• pp.1301-1312
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• 2000

본 논문에서는 트렐리스 복호 방식을 이용한 블록 터보 부호의 이로적인 성능 바운드와 함께 내부 구성 부호의 변형 및 내부 구성 부호의 연결 방법에 따른 성능의 변화를 살펴본다. 또한 효율적인 복잡도 감소 기법을 적용한 반복 복호 기법을 소개하고 시뮬레이션을 통하여 성능을 분석한 결과를 제시한다. 가우시안 채널에서의 시뮬레이션 결과에 따르면 본 논문에서 제시한 기법은 약 1/10정도의 복잡도를 가지고서도 전체 트렐리스를 탐색한 기법에 거의 근접하는 성능을 얻을 수 있음이 보여졌다.

• Journal of Communications and Networks
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• v.5 no.2
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• pp.135-140
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• 2003

In this paper, we investigate the error performance of a serially concatenated system using a nonrecursive convolutional code as the outer code and a recursive QPSK space-time trellis code as the inner code on quasi-static and rapid Rayleigh fading channels. At the receiver, we consider iterative decoding based on the maximum a posteriori (MAP) algorithm. The performance is evaluated by means of computer simulations and it is shown that better error performance can be obtained by using low complexity outer and/or inner codes and the Euclidean distance criterion based recursive space-time inner codes. We also obtain new systems with large number of trasmit and/or receive antennas providing good error performance.

• 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.