• Title/Summary/Keyword: trellis

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A Study on Performance of Parmatic Coding and TCM in Rayleigh Fading Environment (Rayleigh 페이딩하에서 pragmatic 부호와 TCM의 성능에 관한 연구)

  • 강민정;방성일;진년강
    • The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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    • v.4 no.1
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    • pp.20-27
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    • 1993
  • In this paper, a model of TCM / M-PSK with set partitioning and a model of the combined M-ary PSK system with pragmatic coding for digital radio communication are realized. The equations of error probability for TCM / M-PSK system and the combined M-ary PSK system with pragmatic coding are derived on the conditions of the Rayleigh fading with the AWGN. It is found that the combined M-ary PSK systemwith pragmatic coding in the AWGN channel can not be applied to the fading channel since uncoded bits cause parallel:parallel paths in the trellis diagram to degrade the performance of the system. However, the use of pragmatic coding in the AWGN channel could simplify the given system since single convolutional encoder / decoder is required.

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An Improvement of BER Performance for Coded 16-QAM over Mobile Communication Channel by Asymmetric Signal Constellation (비대칭 신호점에 의한 부호화된 16-QAM의 이동 무선 채널에서의 BER 성능 개선에 관한 연구)

  • 김태헌;하덕호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.8 no.2
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    • pp.197-206
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    • 1997
  • The purpose of this paper is to propose an improvement method of BER for coded 16QAM over Rayleigh fading channel. To overcome the BER degradation due to the fading under mobile communication, we apply trellis coded modulation technique which is efficient to get a coding gain without the expansion of bandwidth. Especially, to minimize the burst error which are the main factor of the BER degradation for mobile communication systems, we apply interleaving/deinterleaving method to the studying system. Also we apply asymmetric signal mapping methods to this TCM scheme. From the computer simulation, BER performance of asymmetric case has achieved about 1 dB improvement of about $10^{-4}$, compared to the traditional symmetric case.

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Iterative Multiple Symbol Differential Detection for Turbo Coded Differential Unitary Space-Time Modulation

  • Vanichchanunt, Pisit;Sangwongngam, Paramin;Nakpeerayuth, Suvit;Wuttisittikulkij, Lunchakorn
    • Journal of Communications and Networks
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    • v.10 no.1
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    • pp.44-54
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    • 2008
  • In this paper, an iterative multiple symbol differential detection for turbo coded differential unitary space-time modulation using a posteriori probability (APP) demodulator is investigated. Two approaches of different complexity based on linear prediction are presented to utilize the temporal correlation of fading for the APP demodulator. The first approach intends to take account of all possible previous symbols for linear prediction, thus requiring an increase of the number of trellis states of the APP demodulator. In contrast, the second approach applies Viterbi algorithm to assist the APP demodulator in estimating the previous symbols, hence allowing much reduced decoding complexity. These two approaches are found to provide a trade-off between performance and complexity. It is shown through simulation that both approaches can offer significant BER performance improvement over the conventional differential detection under both correlated slow and fast Rayleigh flat-fading channels. In addition, when comparing the first approach to a modified bit-interleaved turbo coded differential space-time modulation counterpart of comparable decoding complexity, the proposed decoding structure can offer performance gain over 3 dB at BER of $10^{-5}$.

Performance Analysis of STTC-based Dual Virtual Cell System under The Overlay Convergent Networks of Cognitive Networking (중첩 융합 네트워크 환경에서 STTC기반 이중 셀 시스템의 성능분석)

  • Kwon, Eun-Mi;Kim, Jeong-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.7A
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    • pp.528-534
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    • 2012
  • In order to achieve high capacity and reliable link quality of the overlay convergent networks with the cognitive networking based on the advanced capability of the mobile terminal, a Distributed Wireless Communication System (DWCS) can provide the capability of enhancing the link quality. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on radio resource monitering. The considered system constructs DVC for multi-user high-rate data transmission, and the DWCS system exploits space-time trellis codes i.e., STTC to improve a spectral efficiency. The effects of imperfect CSI(channel state information) on the system performance has also been investigated.

Performance Comparison of SFBC/SFTC-OFDM Systems Under MB-OFDM Interference (MB-OFDM UWB 신호 간섭하에서 SFBC/SFTC-OFDM 시스템들의 성능 비교)

  • Kim, Kyung-Seok;Song, Chang-Kun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.10A
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    • pp.968-975
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    • 2006
  • Research about the mode of MIMO that can get a coding benefit at the same time with a diversity benefit using a multiple antenna at the fading channel for a high-speed data transmission have been processed actively But the analysis about the interference of UWB system comes not to consist yet. So this paper analyzed the performance of the interference of UWB system to SFBC-OFDM and SFTC-OFDM system that applied a space block code which has a space diversity characteristic to OFDM system at MIMO channel. We shelved the performance that SFTC-OFDM system is robuster than SFBC-OFDM system under MB-OFDM UWB Interference.

Enhanced-xVSB Development for Next Generation Terrestrial DTV Transmission System (차세대 지상파 DTV 전송방식 시스템을 위한 Enhanced-xVSB 개발)

  • Kim Sung-Hoon;Ji Kum-Ran;Lee Jae-Youn;Kim Seung-Won;Lee Soo-In;Kim Chang-Joong;Lee Ho-Kyoung
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2004.11a
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    • pp.281-284
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    • 2004
  • This paper described an Enhanced-xVSB system for improving mobile/pedestrian reception performance to the ATSC DTV 8-VSB transmission standard. E-xVSB system can transmit a mixture of normal (8-VSB) stream and enhanced (robust) stream. The robust stream has a higher threshold of visibility (TOV) compared to the standard stream, and legacy receivers ignore the robust packets. Thus, Enhanced-xVSB system is fully backward compatible with a current ATSC standard. for mobile and portable reception support, E-xVSB system adopts a reduced constellation method as well as enhanced trellis-coded modulation scheme. E-xVSB system supports a variety of enhanced modulation schemes: Pseudo-2VSB, Enhanced-4VSB, modified Enhanced-8VSB and Hybrid-VSB. Proposed E-xVSB system performs well under serious dynamic multipath reception environment.

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An Efficient Fading Estimation and Compensation Techniques for Transmission of Trellis Coded 16 QAM in Wireless Communication Channel (무선통신채널에서 트렐리스 부호화한 16 QAM 신호전송을 위한 효율적인 페이딩 추정.보상방안)

  • 김순영;김정수;이광재;이문호
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.10 no.6
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    • pp.855-865
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    • 1999
  • This paper presents the improvement of BER performance using fading compensation method for 16 QAM-TCM to reduce the effects of multi-path fading in mobile radio environments. We propose the multi-pilot symbol aided fading compensation technique using Gausian interpolation method for inter-symbol interference or fading distortion occured in frequency selective fading channel. The proposed system is combined coding and modulation scheme for improving the reliability of a digital transmission system without increasing the transmitted power or the required bandwidth. In the fading compensation, the pilot symbols from a known sequence is multiplexed into the data symbols at regular intervals to from a frames for transmission. And we use a modified bit reversal block interleaver to randomize burst errors. The results show that significant improvements in the bit-error rate performances can be achieved by the proposed techniques.

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Design of R=1/2, K=7 Type High Speed Viterbi Decoder with Circularly Connected 2-D Analog Parallel Processing Cell Array (아날로그 2차원 셀의 순환형 배열을 이용한 R=l/2. K=7형 고속 비터비 디코더 설계)

  • 손홍락;김형석
    • The Transactions of the Korean Institute of Electrical Engineers D
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    • v.52 no.11
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    • pp.650-656
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    • 2003
  • A high speed Viterbi decoder with a circularly connected 2-dimensional analog processing ceil array Is proposed. The proposed Viterbi .decoder has a 2-dimensional parallel processing structure in which an analog processing cell is placed at each node of a trellis diagram, the output column of the analog processing cells is connected to the decoding column, and thus, the output(last) column becomes a column right before the decoding(first) column. The reference input signal given at a decoding column is propagated to the whole network while Its magnitude is reduced by the amount of a error metric on each branch. The circuit-based decoding is done by adding a trigger signals of same magnitudes to disconnect the path corresponding to logic 0 (or 1) and by observing its effect at an output column (the former column of the decoding column). The proposed Viterbi decoder has advantages in that it is operated with better performance of error correction, has a shorter latency and requires no path memories. The performance of error correction with the proposed Viterbi decoder is tested via the software simulation.

Design of a Quantization Algorithm of the Speech Feature Parameters for the Distributed Speech Recognition (분산 음성 인식 시스템을 위한 특징 계수 양자화 방식 설계)

  • Lee Joonseok;Yoon Byungsik;Kang Sangwon
    • The Journal of the Acoustical Society of Korea
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    • v.24 no.4
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    • pp.217-223
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    • 2005
  • In this paper, we propose a predictive block constrained trellis coded quantization (BC-TCQ) to quantize cepstral coefficients for the distributed speech recognition. For Prediction of the cepstral coefficients. the 1st order auto-regressive (AR) predictor is used. To quantize the prediction error signal effectively. we use a BC-TCQ. The performance is compared to the split vector quantizers used in the ETSI standard, demonstrating reduction in the cepstral distance and computational complexity.

A Study on the Roadside Slope of the Parkway in Chi-Ri Mountain National Park (智異山 國立公園 道路비탈면에 對한 조사 硏究)

  • Seo, Byung-Soo;Kim, Sei-Cheon;Lee, Chang-Heon;Park, Choung-Min;Lee, Kyu-Wan
    • Journal of the Korean Institute of Landscape Architecture
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    • v.18 no.3 s.39
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    • pp.39-56
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    • 1990
  • The purpose of this study is to analyze the roadside slope of mountainous Parkway. 48 sites were selected by Random Ranking Sampling. This study was researched on the slope condition with the cause of occurrence, the situation of fundamental engineering works and vegetation on slopes. The main results of this research are summarized as follow ; 1. Slope shapes are shown nine types in cut slope and four types in fill slope. 2. Generally, fill slopes are larger than cut slopes in slop area. 3. Grade is more steep than standard grade. 4. Main engineering works, which constructed for slope stability, are terracing, side-ditch wall, channel, concrete trellis works and wire fence. 5. Roundabout channel were many constructed within the sector of Ukmojeong-Deokdong, but were few constructed within the sector of Banseon-Seongsam pass and Cheoneun Temple-Seongsam pass. 6. Most. of side-ditch wall were constructed of concrete and wet-masonry. 7. In vegetation works, many exterior species were selected. 8. Planting pattern was not combinated with the national park landscape.

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