• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.8A
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• pp.1322-1328
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• 2001

본 논문에서는 무선 ATM 환경에서 터보코딩을 이용한 UEP(Unequal Error Protection)을 제안한다. 일반적으로 ATM셀의 header 부분은 payload 부분보다 중요시되며 header 부분에 payload 보다 부호율이 낮은 터보코드를 무선 ATM 적용하여 비트오류확률과 셀손실 확률을 구하였다. 무선 ATM 환경에서 터보코드를 사용하고 프레임길이 28바이트의 DLC 셀구조에서 UEP가 가능함을 보였다. 부호율 1/3인 터보 코딩을 이용한 경우 동일한 부호율의 컨벌루션 코드를 이용한 EEP(Equal Error Protection)과 비교하여 비트 오류확률과 셀 손실율에 있어서 최소 1dB와 2dB 신호대잡음비의 개선을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.6C
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• pp.570-579
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• 2003

The performance of turbo codes is investigated in the direct detection optical PPM channel. We assume that an ideal photon counter is used as an optical detector and that the channel has background noise as well as quantum noise. Resulting channel model is M-ary PPM Poisson channel. We propose the structure of the transmitter and receiver for applying turbo codes to this channel. We also derive turbo decoding algorithm for the proposed coding system, by modifying the calculation of the branch metric inherent in the original turbo decoding algorithm developed for the AWGN channel. Analytical bounds are derived and computer simulation is performed to analyze the performance of the proposed coding scheme, and the results are compared with the performances of Reed-Solomon codes and convolutional codes.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.7
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• pp.39-44
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• 2009

It is well-known that the performance of turbo codes can be improved by allocating different energies per code symbol. In this paper, based on this observation, we propose a joint encoding and modulation scheme for quadrature amplitude modulated turbo code systems. In the proposed scheme, the amount of energy difference between the turbo coded symbols is optimized by optimizing the constellation of quadrature amplitude modulation (QAM). The proposed scheme offers better coding gain compared to the conventional combination of binary turbo code and QAM at the bit error rate of 10$^{-5}$. Also, the performance of binary turbo codes with the proposed QAM constellation for various code symbol mapping strategies are verified.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.11
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• pp.2397-2404
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• 2012

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding scheme, turbo codes and LDPC codes are dominant channel coding schemes in recent. This paper concluded that turbo coding scheme is optimal for underwater communications system in aspect to performance, coded word length, and equalizer combining. Also, decision directed phase recovery was used for correcting phase offset induced by multipath. Based on these algorithms, we confirmed the performance in the environment of oceanic experimentation.

• Journal of Satellite, Information and Communications
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• v.5 no.2
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• pp.40-44
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• 2010

A layered coding scheme is one of the adaptive receiving techniques for unidirectional services such as multimedia broadcasting and multicasting services (MBMS), where we cannot utilize feedback information. The layered coding scheme can be used with hierarchical modulations by combining suitable code rates and modulation orders of each. In addition, it has been reported that hybrid and/or integrated satellite systems can effectively achieve transmit diversity gains by appropriate utilization of space time coding combined with turbo codes. This paper proposes a layered turbo coding schemes for hybrid and/or integrated satellite systems. We first introduce the system architecture and operational principle of the proposed scheme, and discuss the applicability.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38C no.3
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• pp.303-310
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• 2013

Underwater acoustic communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of underwater channel causes signal distortion and error floor. In order to improve the performance, it is necessary to employ an iterative coding scheme. Among the iterative coding scheme, turbo codes and LDPC codes are dominant channel coding schemes in recent. This paper concluded that turbo coding scheme is optimal for underwater communications system in aspect to performance, coded word length, and equalizer combining. Also, we confirmed the performance in the environment of oceanic experimentation using turbo equalizer based on distance 5Km, data rate 1Kbps.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.10A
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• pp.1782-1793
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• 2001

터보부호 심벌비트들을 서로 다른 부호율로 반복부호화한 뒤 여러 부채널로 나란히 보내는 터보 부호화 여러반송파 직접수열 부호분할 다중접속 시스템을 제안한다. 레일리 감쇄채널에서 신호대잡음비가 높을 때에는 이 시스템의 성능 한계를 얻었고, 신호대잡음비가 낮아 한계를 적용할 수 없을 때에는 모의실험에서 성능을 살펴보았다. 신호대잡음비가 낮을 때 성능 손실이 조금 있지만 홀짝 검사(parity check) 심벌에 다양성 차수를 크게 주어 오류 마루를 (error floor) 낮출 수 있음을 보였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2006.11a
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• pp.229-232
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• 2006

본 논문은 AWGN 채널상의 Single Parity Check(SPC) 다차원 product부호에서 LDPC(Low Density Parity Check)부호를 이용한 오류 정정의 성능을 제시한다. 기존 방법인 터보 부호 방식을 이용한 오류 정정과 비교하여 LDPC부호가 갖는 장점을 기술하고 실험을 통해 LDPC 부호를 이용한 오류 정정 성능도 터보부호와 대등함을 보인다.

• Journal of Navigation and Port Research
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• v.36 no.10
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• pp.845-849
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• 2012

The next-generation wireless communication requires fast transmission speeds with various services and high reliability. In order to satisfy these needs we study MIMO system used layered space time coded system (LST) combining space time trellis codes (STTC) with turbo codes. In LST, two codes that are inner and outer codes are concatenated in the serial fashion. The inner codes are turbo Pi codes suggested in DVB-RCS NG system, and outer codes are STTC codes proposed by Blum. The interleaver technique is used to efficiently combine two codes. And we proposed and simulated that a full iteration method between turbo decoder and BCJR decoder to improve the performance instead of only processing inner-iteration turbo decoder. The simulation results of proposed effective layered method show improving BER performance about 1.3~1.5dB than conventional one.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.7A
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• pp.1074-1079
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• 1999

In this paper, the concept of puncturing is introduced to turbo code in order to implement various code as code rate varies.rates. First, several different puncturing matrices are applied into rate 1/3 encoder in order to produce various rate 1/2 turbo codes. By analyzing and comparing these results, we can show which puncturing pattern should be selected in order to maintain good performance. Second, we select some appropriate puncturing patterns which provide the best performance of turbo codes of various rates from 1/3 to 2/3 among all the possible candidates. Finally, we provide the change of required Eb/No at $P_b=10^{-4}$ as code rate varies.