• Title/Summary/Keyword: 트렐리스

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PRML detection using the patterns of run-length limited codes (런-길이 제한 코드의 패턴을 이용한 PRML 검출 방법)

  • Lee Joo hyun;Lee Jae jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.30 no.3C
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    • pp.77-82
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    • 2005
  • Partial response maximum likelihood (PRML) detection using the Viterbi algorithm involves the calculation of likelihood metrics that determine the most likely sequence of decoded data. In general, it is assumed that branches at each node in the trellis diagram have same probabilities. If modulation code with minimum and maximum run-length constraints is used, the occurrence ratio (Ro) of each particular pattern is different, and therefore the assumption is not true. We present a calculation scheme of the likelihood metrics for the PRML detection using the occurrence ratio. In simulation, we have tested the two (1,7) run-length-limited codes and calculated the occurrence ratios as the orders of PR targets are changed. We can identify that the PRML detections using the occurrence ratio provide more than about 0.5dB gain compared to conventional PRML detections at 10/sup -5/ BER in high-density magnetic recording and optical recording channels.

Optimum and Sub-optimum Decoding Methods of Space-Time Trellis Coded Code Division Multiple Access Systems (시공간 트렐리스 부호화 CDMA 시스템의 최적, 준최적 복호 방식과 성능 연구)

  • Ki, Young Min;Kim, Dong Ku
    • Journal of Advanced Navigation Technology
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    • v.6 no.2
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    • pp.130-137
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    • 2002
  • We present Space-Time Trellis Coded Code Division Multiple Access systems, which maintain the full diversity and coding gain of Space-Time Trellis Codes(STTC) and have the immunity to performance degradation caused by multipath fading. These STTC CDMA systems are constructed by adding the spreading and despreading processes of PN codes to STTC systems. In multipath fading channels, delay spreaded signals are detected and combined, then decoded. According to the combining and decoding methods, there are four decoding methods. There are optimum ML decoding without combining, adding multipath signals in each receive antenna before decoding, combining multi path signals in each antenna before decoding, and combining all received signals before decoding. Performance of these methods is proportional to complexity. Besides, all methods are shown to compensate the irreducible error rate which appears in multipath fading channels.

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Improvement Transmission Reliability between Flight Type Air Node Using Concatenated Single Antenna Diversity (비행형 에어노드의 데이터 전송 신뢰성 향상을 위한 연접 단일 안테나 다이버시티 시스템)

  • Kang, Chul-Gyu;Kim, Dae-Hwan
    • Journal of Advanced Navigation Technology
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    • v.15 no.6
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    • pp.1053-1058
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    • 2011
  • In this paper, we propose a concatenated single antenna diversity system to assure the data transmission reliability between flight type air nodes which move according to their atypical orbit, then analyze its performance. The proposed system achieve a diversity gain using single antenna and a coding gain from convolutional code simultaneously. Simulation result about the bit error rate(BER) of the proposed system shows that its BER performance is about 9.5dB greater than convolutional code at $10^{-4}$ and about 14dB greater than space time block code at $10^{-3}$ which has a full diversity gain. In addition, compared with space time trellis code with diversity gain and coding gain, the proposed system shows the better 4dB at a BER of $10^{-5}$. Therefore, it is necessary that concatenated single antenna diversity should be adopted to the reliable data transmission of flight type air nodes.

Performance Analysis of Operation Strategy of Dual Virtual Cell-based System under The Overlay Convergent Networks of Cognitive Networking (인지 네트워킹 기반 중첩 융합 네트워크에서 이중 가상 셀 운영방안의 성능분석)

  • Choi, Yu-Mi;Kim, Jeong-Ho
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.6B
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    • pp.483-488
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    • 2012
  • With the fast growing data traffic, the performance of the convergent overlay network environment under the cognitive networking environment is crucial for the implementation of the efficient network structure. In order to achieve high capacity and reliable link quality in wireless communication 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 ambient-aware dual cell system's operation. This paper has considered virtual cell: the Dual Virtual Cell (DVC), and also proposes DVC employment strategy based on DWCS network. One is the Active Virtual Cell which exists for user's actual data traffic and the other is the Candidate Virtual Cell which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. The considered system constructs DVC by using cognitive ability of finding useful virtual signals. Also, for multi-user high-rate data transmission, the DWCS system exploits Space-Time Trellis Codes. The effects of changing environments on the system performance has been investigated thereafter.

A Study of Efficient Viterbi Equalizer in FTN Channel (FTN 채널에서의 효율적인 비터비 등화기 연구)

  • Kim, Tae-Hun;Lee, In-Ki;Jung, Ji-Won
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.18 no.6
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    • pp.1323-1329
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    • 2014
  • In this paper, we analyzed efficient decoding scheme with FTN (Faster than Nyquist) method that is transmission method faster than Nyquist theory and increase the throughput. we proposed viterbi equalizer model to minimize ISI (Inter-Symbol Interference) when FTN signal is transmitted. the proposed model utilized interference as branch information. In this paper, to decode FTN singal, we used turbo equalization algorithms that iteratively exchange probabilistic information between soft Viterbi equalizer (BCJR method) and LDPC decoder. By changing the trellis diagram in order to maximize Euclidean distance, we confirmed that performance was improved compared to conventional methods as increasing throughput of FTN signal.

Improved Differential Detection Scheme of Space Time Trellis Coded MDPSK For MIMO (MIMO에서 시공간 부호화된 MDPSK의 성능을 향상시키기 위한 차동 검파 시스템)

  • Kim, Chong-Il;Lee, Ho-Jin;Yoo, Hang-Youal;Kim, Jin-Yong;Kim, Seung-Youal
    • 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.

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A Watermarking Method Based on the Informed Coding and Embedding Using Trellis Code and Entropy Masking (Trellis 부호 및 엔트로피 마스킹을 이용한 정보부호화 기반 워터마킹)

  • Lee, Jeong-Hwan
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.13 no.12
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    • pp.2677-2684
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    • 2009
  • In this paper, we study a watermarking method based on the informed coding and embedding by means of trellis code and entropy masking. An image is divided as $8{\times}8$ block with no overlapping and the discrete cosine transform(DCT) is applied to each block. Then the 16 medium-frequency AC terms of each block are extracted. Next it is compared with gaussian random vectors having zero mean and unit variance. As these processing, the embedding vectors with minimum value of linear combination between linear correlation and Watson distance can be obtained by Viterbi algorithm at each stage of trellis coding. For considering the image characteristics, we apply different weight value between the linear correlation and the Watson distance using the entropy masking. To evaluate the performance of proposed method, the average bit error rate of watermark message is calculated from different several images. By the experiments the proposed method is improved in terms of the average bit error rate.

Design and Implementation of 4D-8PSK TCM Simulator for Satellite Communication Systems (4D-8PSK TCM 위성통신 시스템 시뮬레이터 설계 및 구현)

  • Kim, Dohwook;Kim, Joongpyo;Kim, Sanggoo;Yoon, Dongweon
    • The Journal of Korean Institute of Information Technology
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    • v.17 no.3
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    • pp.31-41
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    • 2019
  • In this paper, we design and implement the simulator for the transmitter and receiver of 4D-8PSK TCM with 2.0, 2.25, 2.5, and 2.75 bits/symbol-channel transmission efficiency recommended by the CCSDS for satellite communications, and then analyze the BER performance of 4D-8PSK TCM system in AWGN channel. The transmitter of 4D-8PSK TCM is designed in accordance with the recommendation in the CCSDS standard. Meanwhile, for the receiver design of 4D-8PSK TCM, we design the differential decoder generalizing the differential encoder/decoder scheme. The trellis decoding algorithm is designed by applying the auxiliary trellis information and the Viterbi algorithm, and an 8-dimensional constellation mapper equation given in the CCSDS standard is deconstructed to design constellation mapper. Especially, we present the optimized receiver for 4D-8PSK TCM system by investigating the BER performances for the traceback lengths in the Viterbi decoder through computer simulations..

Low Complexity Linear Receiver Implementation of SOQPSK-TG Signal Using the Cross-correlated Trellis-Coded Quadrature Modulation(XTCQM) Technique (SOQPSK-TG 신호의 교차상관 격자부호화 직교변조(XTCQM) 기법을 사용한 저복잡도 선형 수신기 구현)

  • Kim, KyunHoi;Eun, Changsoo
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.3
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    • pp.193-201
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    • 2022
  • SOQPSK-TG is a modulated signal for aircraft telemetry with excellent frequency efficiency and power efficiency. In this paper, the phase waveform of the partial response SOQPSK-TG modulation is linearly approximated and modeled as a full response double duobinary SOQPSK (SOQPSK-DD) signal. And using the XTCQM method and the Laurent decomposition method, the SOQPSK-DD signal was approximated as OQPSK having linear pulse waveforms, and the results of the two methods were proved to be the same. In addition, it was confirmed that the Laurent decomposition waveform of the SOQPSK-DD signal approximates the Laurent decomposition waveform of the original SOQPSK-TG signal. And it was shown that the decision feedback IQ-detector, which applied the Laurent decomposition waveform of SOQPSK-DD to the detection filter, exhibits almost the same performance even with a simpler waveform than before.

Concatenated Diversity System for Bandwidth Efficient Communication of Flight Type Air Node in Unstable Channel Environments (비정형 통신 채널 환경에서 비행형 에어노드의 대역 효율적인 통신을 위한 연접 다이버시티 시스템)

  • Kang, Chul-Gyu;Park, Jin-Hee;Oh, Chang-Heon
    • Journal of Advanced Navigation Technology
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    • v.16 no.2
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    • pp.247-254
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    • 2012
  • In this paper, we propose a concatenated diversity system to assure the data transmission reliability between flight type air nodes which move according to their atypical orbit, then its performance is analyzed using computer simulation and it is designed with hdl. The proposed system cannot only improve a bandwidth efficient and coding gain from diversity TCM code but also the reliability of data transmission is high. From the computer simulation result about bit error rate(BER) of the proposed system, we confirm that its BER performance is about 11dB greater than TCM code at $10^{-2}$ and about 11dB greater than space time block code at $10^{-3}$ which has a full diversity gain. In addition, when we compare its BER performance with space time trellis code which has both a diversity gain and a coding gain, the performance of the proposed system is greater than about 1.5dB at $10^{-5}$. Lastly, after designing the proposed system with HDL, we can confirm that the operation result is correct.