• Title/Summary/Keyword: 반복부호

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Performance Experimentation and an Optimal Iterative Coding Algorithm for Underwater Acoustic Communication (수중음향통신에서 최적의 반복부호 알고리즘 및 성능 실험)

  • Park, Gun-Yeol;Lim, Byeong-Su;Jung, Ji-Won
    • 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.

Adapt ive Iteration Decoding Preset Method of LDPC Codes by SNR Estimation & Decoder Structure (LDPC 부호의 적응적 반복 복호수 설정 방식 및 복호기 구조)

  • 이정훈;장진수;정영일;이문호
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.773-776
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    • 2001
  • 열악한 전송 환경에서 고품질, 고신뢰성 통신을 지속적으로 하기 위해서 오류 정정 부호는 필수 적이다. 최근에 반복 복호를 통해 샤논의 채널 용량 한계에 근접하는 터보 부호와 LDPC부호가 가장 관심을 불러일으키고 있다. 반복 복호법은 성능 면에서는 우수해 지나 이에 따른 계산량 증가와 지연이 수반된다. 따라서 본 논문에서는 모의 실험을 통한 수신 데이터를 이용, SNR을 추정하여 LDPC 부호의 최대 반복 복호수에 따른 계산량과 지연을 효과적으로 줄일 수 있는 적응적 반복 복호수 설정 방식을 제안한다.

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Locally Repairable Fractional Repetition Codes (부분접속 복구 가능한 반복분할 부호)

  • Nam, Mi-Young;Kim, Jung-Hyun;Song, Hong-Yeop
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.40 no.9
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    • pp.1741-1753
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    • 2015
  • In this paper, we introduce new locally repairable codes based on a Fractional repetition codes which is one of the MBR codes. We introduce two different constructions for different system parameters and compare these codes in terms of several performance metrics. There is some tradeoffs between the locality and other performance metrics. The newly introduced codes having the good locality should pay the price such as lower capacity or more storage nodes. And the proposed codes are more reliable than other locally repairable codes and have lower repair complexity since they can be repaired without any operations.

Variable Iteration Decoding Control Method of Iteration Codes using CRC-code (CRC부호를 이용한 반복복호부호의 반복복호 제어기법)

  • Baek, Seung-Jae;Park, Jin-Soo
    • The KIPS Transactions:PartC
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    • v.11C no.3
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    • pp.353-360
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    • 2004
  • In this Paper, We propose an efficient iteration decoding control method with variable iteration decoding of iteration codes decoding using Cyclic Redundancy Check. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, when the iteration decoding number is increased, it require much delay and amount of processing time for decoding. Also, It can be observed the error nor that the performance cannot be improved even though increasing of the number of iterations and SNR. So, Suitable number of iterations for stopping criterion is required. we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the amount of computation and the number of iterations required for iteration decoding with CRC method can be reduced without sacrificing performance.

Variable Iteration Decoding Control Method for Iteration Codes (Iteration 부호의 가변반복복호 제어기법)

  • 백승재;이성우;박진수
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2003.05a
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    • pp.753-757
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    • 2003
  • In this paper, We propose an efficient iteration decoding control method with variable iteration decoding for iteration codes decoding. As the number of iterations increases, the bit error rate and frame error rate of the decoder decrease and the incremental improvement gradually diminishes. However, as the iteration decoding number is increase, it require much delay and amount of processing for decoding. Thus we propose variable iteration control method to adapt variation of channel using Frame Error-Check indicator. Therefore, the CRC method requires the fewest iterations and less computation than the CE method and the SCR methods.

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MPEG Audio Layer-III Encoder Using Approximated Psy-choacoustic Model (간략화된 심리음향모델을 이용한 MPEG Audio Layer-III 부호화기)

  • 송창준;오현오;박영철;윤대희
    • Proceedings of the IEEK Conference
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    • 2001.09a
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    • pp.469-472
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    • 2001
  • MPEC Audio Layer-III(MP3)알고리듬은 복호화기에 비해 부호화기가 월등히 많은 연산량을 가지고 있는 비대칭 구조를 가지고 있다. MP3 부호화기의 대부분의 연산량은 복잡한 초월함수 연산이 포함되는 심리음향모델과 반복 루프 과정을 수행하는 비선형 양자화와 비트 할당과정 이 차지한다. 본 논문에서는 MP3 부호화기의 실시간 구현을 위한 알고리듬 레벨의 최적화를 수행하였다. MP3 부호화기의 연산량을 줄이기 위해 심리음향모델을 간략화하고 반복 루프의 회수를 최소화할 수 있는 방법을 제안하였다. 프레임당 한 그래뉼의 심리음향모델 정보를 계산하여 한 프레임 내에서의 심리음향모델 정보를 추정함으로써 연산량을 45% 이상 감소시켰다. 또한 외부 반복 루프의 반복 회수를 줄이기 위하여 외부 반복 루프의 반복에 따른 스케일 팩터(Scale Factor) 및 양자화 스탭의 증가 패턴을 관찰하고 최적화된 스캐일 팩터 증가 방법을 제안하였다. 제안된 고속화 방법은 주관적 음질 평가를 통해 성능을 검증하였다.

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Efficient stop criterion algorithm of the turbo code using the maximum sign change of the LLR (LLR 최대부호변화를 적용한 터보부호의 효율적인 반복중단 알고리즘)

  • Shim Byoung-Sup;Jeong Dae-Ho;Lim Soon-Ja;Kim Tae-Hyung;Kim Hwan-Yong
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.43 no.5 s.347
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    • pp.121-127
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    • 2006
  • It is well known the fact that turbo codes has better performance as the number of iteration and the interleaver size increases in the AWGN channel environment. However, as the number of iteration and the interleaver size are increased, it is required much delay and computation for iterative decoding. Therefore, it is important to devise an efficient criterion to stop the iteration process and prevent unnecessary computations and decoding delay. In this paper, it proposes the efficient stop criterion algorithm for turbo codes using the maximum sign change of LLR. It is verifying that the proposal variable iterative decoding controller can be reduced the average iterative decoding number compared to conventional schemes with a negligible degradation of the error performance.

Distributed Storage Codes with Multiple Replication Degrees Using Relative Difference Families (상대 차족을 이용한 복수 반복 차수 분산 저장 부호)

  • Park, Hosung;Kim, Cheol-Sung
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.12
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    • pp.1768-1770
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    • 2016
  • In this paper, we propose a construction method of fractional repetition codes, a class of distributed storage codes, using relative difference families. The proposed codes can support multiple replication degrees for data symbols. It is shown via simulation that the proposed codes store more data than the random fractional repetition codes.

Minimum Distance Search Algorithms of LDPC Codes and RA Codes (LDPC 부호와 RA 부호의 최소 거리 검색 알고리즘)

  • Chung Kyu-Hyuk
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.31 no.3A
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    • pp.207-213
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    • 2006
  • In this paper, we reduce the computational complexity to find the minimum distance of RA codes by searching only valid codewords using repetition part. Since LDPC codes have repetition part like RA codes, we also apply this algorithm for computing the minimum distance of LDPC codes. The minimum distance dominates the code performance at high signal-to-noise ratios(SNRs) and in turn allows an estimate of the error floor. The proposed algorithm computes the minimum distance without any constraint on code structures. The minimum distances of LDPC codes and RA codes with large interleavers of practical importance are computed and used to obtain the error floor, which is compared with the performance of the iterative decoding.

Analysis of Optimum Iterative Codes for Underwater Acoustic Communication based on Turbo Equalizer (수중 음향통신에 적합한 터보 등화기 기반의 최적의 반복 부호 기법 연구)

  • Park, Tae-Doo;Jung, Ji-Won
    • Journal of Navigation and Port Research
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    • v.37 no.5
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    • pp.487-492
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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, LDPC codes and convolutional code based on BCJR algorithm are dominant channel coding schemes in recent. Therefore this paper analyzed the performance of iterative codes based on turbo equalizer with the same coding rate and similar codeword length. The performances of three kinds of iterative codes were evaluated in the environment of underwater acoustic communication channel that are real data collected in Korean east sea. The distance of transmitter and receiver was 5Km and data rate was 1Kbps. As a result, convolutional code based on BCJR algorithm has better performance in underwater channel than turbo codes and LDPC codes.