• Title/Summary/Keyword: LDPC부호

Search Result 191, Processing Time 0.021 seconds

A New LDPC Decoding Method of Error Correction Decoder for Distributed Video Coding (분산 동영상 압축 기법에 사용되는 LDPC 부호의 새로운 복호화 기법)

  • Lee, Sangwoo;Jang, Hwanseok;Park, Sang Ju
    • Proceedings of the Korean Society of Broadcast Engineers Conference
    • /
    • 2011.11a
    • /
    • pp.229-231
    • /
    • 2011
  • H.264/AVC와 같은 동영상 압축 기술은 동영상의 압축에 필요한 연산이 대부분 부호기에서 이루어진다. 반면에 분산 동영상 압축 기법은 정보 압축에 필요한 연산이 대부분 복호기에서 수행되는 구조를 가진다. 본 논문에서는 분산 동영상 압축 기법의 구성 요소 중 오류 정정 부호기와 복호기에 사용되는 오류 정정 부호 중 LDPC 부호의 성능을 향상 시킬 수 있는 새로운 복호 기법을 제안한다. 제안하는 기법을 적용하여 추가적인 연산 없이 LDPC 부호의 오류 정정 성능을 향상시킬 수 있었다.

  • PDF

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
    • /
    • v.16 no.11
    • /
    • pp.2397-2404
    • /
    • 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.

On the Absorbing Sets of the Regular LDPC Codes with Variable Node Degree Three (변수노드의 차수가 3인 정칙 LDPC 부호의 Absorbing 집합에 관하여)

  • Lee, Ki-Jun;Chung, Ha-Bong;Jang, Hwan-Seok
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.34 no.10C
    • /
    • pp.937-945
    • /
    • 2009
  • In this paper, we investigate into the existence and various properties of absorbing sets in regular LDPC codes with variable node degree three. Also, we figure out the critical number of some absorbing sets that are believed to be the major cause of error floor in (3,5) Tanner LDPC codes.

Fast Multi-Rate LDPC Encoder Architecture for WiBro System (WiBro 시스템을 위한 고속 LDPC 인코더 설계)

  • Kim, Jeong-Ki;S.P., Balakannan;Lee, Moon-Ho
    • Journal of the Institute of Electronics Engineers of Korea TC
    • /
    • v.45 no.7
    • /
    • pp.1-8
    • /
    • 2008
  • Low Density Parity Check codes(LDPC) are recently focused on communication systems due to its good performance. The standard of WiBro has also included LDPC codes as a channel coding. The weak point of implementation for LDPC encoder is that conventional binary Matrix Vector Multiplier has many clock cycles which limit throughput. In this paper, we propose semi-parallel architecture by using cyclic shift registers and exclusive-OR without conventional Matrix Vector Multipliers over the standard parity check matrices with Circulant Permutation Matrices(CPM). Furthermore, multi-rate encoder is designed by using proposed architecture. Our encoder with multi-rate for IEEE 802.16e LDPC has lower clock cycles and higher throughput.

Secret key information reconciliation protocol using LDPC code (LDPC 부호를 이용한 암호키 정보 보정 프로토콜)

  • Lee, Sunghoon;Heo, Jun
    • Proceedings of the Korean Society of Broadcast Engineers Conference
    • /
    • 2014.11a
    • /
    • pp.228-229
    • /
    • 2014
  • 양자 키 분배는 안정한 통신을 위해 고안된 암호 체계이다. 양자 키 분배의 후처리 과정 중 정보 보정은 두 적법한 사용자 간의 연관 관계가 있는 정보를 일치시키는 과정이다. 고전 오류 정정 과정과 비슷하며 이 과정을 위해 추가 정보를 주고받기 때문에 도청자에게 일정량의 정보가 노출된다. 따라서 정보 보정 프로토콜에서 노출된 정보량은 프로토콜의 성능을 결정하는 중요한 요인이 된다. 본 논문에서는 Winnow 프로토콜과 LDPC 부호를 이용한 프로토콜을 노출된 정보량과 평균 통신 횟수 측면에서 비교한다. 그 결과로 Winnow 프로토콜에 비해 LDPC 부호를 이용한 프로토콜이 현재 양자 키 분배 시스템에서 더 좋은 기술이 될 수 있음을 보인다. 또한 LDPC 부호를 이용한 프로토콜이 가지는 단점을 극복할 수 있는 향후 연구 방향을 제시한다.

  • PDF

Upper Bounds of Maximum Likelihood (ML) Decoding Performance of a few Irregular LDPC Codes (몇 개의 불규칙한 LDPC 부호의 Maximum Likelihood(ML) 복호에 대한 성능의 상향 한계와 정점 성능 감쇠 분석)

  • Chung, Kyu-Hyuk
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.34 no.11C
    • /
    • pp.1025-1028
    • /
    • 2009
  • This paper presents upper bounds of Maximum Likelihood (ML) decoding performance of a few irregular LDPC codes using the simple bound and ML input output weight distributions and it is shown that contrary to general opinion that as block length becomes longer, BP decoding performance becomes simply closer to ML decoding performance, before peak degradation, as block length becomes longer, BP decoding performance falls behind ML decoding performance more and after peak degradation, general opinion holds.

Quasi-Cyclic LDPC Codes by random combination of multiple sub-matrices (여러 부행렬들의 무작위 조합으로 만든 Quasi-Cyclic LDPC 부호)

  • Hwang, Yongsoo;Oh, Sanghoun;Jeon, Moongu
    • Proceedings of the Korea Information Processing Society Conference
    • /
    • 2010.04a
    • /
    • pp.631-634
    • /
    • 2010
  • 기존의 Quasi-Cyclic LDPC 부호는 하나의 기본행렬의 순환행렬을 부행렬로 사용하여 패리티 검사 행렬을 만든다. 본 논문에서는 무게가 서로 다른 두 개의 기본 행렬의 순환행렬들과 영행렬을 부행렬로 사용하고, 이 세 개의 부행렬들을 주어진 조건하에서 무작위로 조합하여 패리티 검사 행렬을 만드는 방법을 제안한다. 제안된 LDPC 부호는 girth가 6이상인 Irregular LDPC 부호이다.

Performance Analysis of CZZ Codes Using Degree-2 Polynomial Interleavers for Fading Channels (페이딩 채널에서 2차 다항식 인터리버를 사용한 CZZ 부호의 성능 분석)

  • Yun, Jeong-Kook;Yoo, Chul-Hae;Shin, Dong-Joon
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.33 no.12C
    • /
    • pp.1006-1013
    • /
    • 2008
  • CZZ (Concatenated Zigzag) Code is a class of fast encodable LDPC codes. In the case that LDPC codes including CZZ codes have short length, short cycles seriously affect the code performance. In this paper, we construct CZZ codes using various degree-2 polynomial interleavers which eliminate cycles of length 4 and through simulation, compare the performance of these CZZ codes and turbo codes in many different fading channels. Especially, quasi-static fading channel, block fading channel, uncorrelated fading channel, and correlated fading channel are considered. Since CZZ codes show similar performance as turbo codes, they can be used in the next generation wireless communication systems.

Performance Analysis of LDPC code with Channel Estimation in Underwater Communication (수중통신 채널에서 채널 추정 오차에 따른 LDPC 부호 성능분석)

  • Kim, Nam-Soo;Jung, Ji-Won;Kim, Ki-Man;Seo, Dong-Hoan
    • Journal of the Korea Institute of Information and Communication Engineering
    • /
    • v.13 no.11
    • /
    • pp.2295-2303
    • /
    • 2009
  • Underwater acoustic(UWA) communication has multipath error because of reflection by sea-level and sea-bottom. The multipath of UWA channel causes signal distortion and error floor. In this paper, we proposed the compensation method of multipath effect using the impulse response of the UWA channel and then analysis the performance of channel coding such as LDPC code, concatenate code. Also we analysed the time-delay errors and estimated amplitude errors of estimated channel information and its affection on the performance. As shown in simulation results, the performance of proposed compensation method is better than the performance of conventional method.

UEP Effect Analysis of LDPC Codes for High-Quality Communication Systems (고품질 통신 시스템을 위한 LDPC 부호의 UEP 성능 분석)

  • Yu, Seog Kun;Joo, Eon Kyeong
    • The Journal of Korean Institute of Communications and Information Sciences
    • /
    • v.38A no.6
    • /
    • pp.471-478
    • /
    • 2013
  • Powerful error control and increase in the number of bits per symbol should be provided for future high-quality communication systems. Each message bit may have different importance in multimedia data. Hence, UEP(unequal error protection) may be more efficient than EEP(equal error protection) in such cases. And the LDPC(low-density parity-check) code shows near Shannon limit error correcting performance. Therefore, the effect of UEP with LDPC codes is analyzed for high-quality message data in this paper. The relationship among MSE(mean square error), BER(bit error rate) and the number of bits per symbol is analyzed theoretically. Then, total message bits in a symbol are classified into two groups according to importance to prove the relationship by simulation. And the UEP performance is obtained by simulation according to the number of message bits in each group with the constraint of a fixed total code rate and codeword length. As results, the effect of UEP with the LDPC codes is analyzed by MSE according to the number of bits per symbol, the ratio of the message bits, and protection level of the classified groups.