• Title, Summary, Keyword: LDPC code

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Performance Evaluation of LDPC-LDPC Product Code for next Magnetic Recording Channel (차세대 자기기록 채널을 위한 LDPC-LDPC 곱 부호의 성능 평가)

  • Park, Donghyuk;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.49 no.11
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    • pp.3-8
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    • 2012
  • Two-dimensional product code has been studied for correcting burst errors on the storage systems. An RS-LDPC product code consists of an RS code in horizontal direction and an LDPC code in vertical direction. First, we detect the position of burst errors by using RS code, then LDPC code corrects the errors by using the burst error positions. In storage system, long burst errors are occurred by various reason. So, we need a strong code for correcting the long burst errors. RS-LDPC product code is good for long burst errors. However, as the storage density grows the length of the burst errors will be longer. Thus, we propose an LDPC-LDPC product code, it is strong for correcting the very long burst errors. Also, the proposed LDPC-LDPC product code performs better than RS-LDPC product code when the random errors are occurred, because a row direction LDPC code performs better than row direction RS code.

The Effect of Block Interleaving in an LDPC-Turbo Concatenated Code

  • Lee, Sang-Hoon;Joo, Eon-Kyeong
    • ETRI Journal
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    • v.28 no.5
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    • pp.672-675
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    • 2006
  • The effect of block interleaving in a low density parity check (LDPC)-turbo concatenated code is investigated in this letter. Soft decoding can be used in an LDPC code unlike the conventional Reed-Solomon (RS) code. Thus, an LDPC-turbo concatenated code can show better performance than the conventional RS-turbo concatenated code. Furthermore, the performance of an LDPC-turbo code can be improved by using a block interleaver between the LDPC and turbo code. The average number of iterations in LDPC decoding can also be reduced by a block interleaver.

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A Comparison of Raptor Code Using LDGM and LDPC code (LDGM와 LDPC code를 이용한 Raptor code의 비교)

  • Liu, Yanji;Suh, Hee-Jong
    • The Journal of the Korea institute of electronic communication sciences
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    • v.8 no.1
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    • pp.65-70
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    • 2013
  • In this paper, we propose the construction of Raptor code using LDGM code instead of LDPC code as precode. To see their merits, the simulations are done. The results show that the performance in case of using LDGM code is worse than that of using LDPC code as precode, and the complexity of encoding LDGM code is lower than that of LDPC.

LDPC Code Design and Performance Analysis for Distributed Video Coding System (분산 동영상 부호화 시스템을 위한 LDPC 부호 설계 및 성능 평가)

  • Noh, Hyeun-Woo;Lee, Chang-Woo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.37 no.1A
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    • pp.34-42
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    • 2012
  • Low density parity check (LDPC) code is widely used, since it shows superior performance close to Shannon limit and its decoding complexity is lower than turbo code. Recently, it is used as a channel code to decode Wyner-Ziv frames in distributed video coding (DVC) system. In this paper, we propose an efficient method to design the parity check matrix H of LDPC codes. In order to apply LDPC code to DVC system, the LDPC code should have rate compatibility. Thus, we also propose a method to merge check nodes of LDPC code to attain the rate compatibility. LDPC code is designed using ACE algorithm and check nodes are merged for a given code rate to maximize the error correction capability. The performance of the designed LDPC code is analyzed extensively by computer simulations.

Design of Low-Density Parity-Check Codes for Multiple-Input Multiple-Output Systems (Multiple-Input Multiple-output system을 위한 Low-Density Parity-Check codes 설계)

  • Shin, Jeong-Hwan;Chae, Hyun-Do;Han, In-Duk;Heo, Jun
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.35 no.7C
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    • pp.587-593
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    • 2010
  • In this paper we design an irregular low-density parity-check (LDPC) code for multiple-input multiple-output (MIMO) system, using a simple extrinsic information transfer (EXIT) chart method. The MIMO systems considered are optimal maximum a posteriori probability (MAP) detector. The MIMO detector and the LDPC decoder exchange soft information and form a turbo iterative receiver. The EXIT charts are used to obtain the edge degree distribution of the irregular LDPC code which is optimized for the MIMO detector. It is shown that the performance of the designed LDPC code is better than that of conventional LDPC code which was optimized for either the Additive White Gaussian Noise (AWGN) channel or the MIMO channel.

Analysis a LDPC code in the VDSL system (VDSL 시스템에서의 LDPC 코드 연구)

  • Joh, Kyung-Hyun;Kang, Hee-Hoon;Yi, Sang-Hoi;Na, Kuk-Hwan
    • Proceedings of the IEEK Conference
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    • pp.999-1000
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    • 2006
  • The LDPC Code is focusing a powerful FEC(Forward Error Correction) codes for 4G Mobile Communication system. LDPC codes are used minimizing channel errors by modeling AWGN Channel as VDSL system. The performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. LDPC code are encoded by sparse parity check matrix. there are decoding algorithms for a LDPC code, Bit Flipping, Message passing, Sum-Product. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten.

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LDPC Coding for image data and FPGA Implementation of LDPC Decoder (영상 정보의 LDPC 부호화 및 복호기의 FPGA구현)

  • Kim, Jin Su;Jaegal, Dong;Byon, Kun Sik
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • pp.887-890
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    • 2009
  • To transmit information over a channel in the presence of noise, there needs some technique to code the information. One of the coding techniques used for error detection and correction close to the Shannon limit is Low Density Parity Code. LDPC and decoding characteristic features by sum-product algorithm are matched for the performance to Turbo Code, RA(Repeat Accumulate) code, in case of very long code length of LDPC surpass their performance. This paper explains LDPC coding scheme of image data and decoding scheme, implements LDPC decoder in FPGA.

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High-rate LDPC Coded OFDM System for Image Transmission over Rayleigh Fading Channel (레일리 페이딩 채널에서 이미지 전송을 위한 고속 LDPC부호를 적용한 OFDM 시스템)

  • Choi, Sang-Min;Moon, Byung-Hyun
    • Proceedings of the KIEE Conference
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    • pp.233-235
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    • 2005
  • As a class of block codes, LDPC code with any desired code rate and code length is easily constructed. In OFDM system high data transmission is possible, In this paper, we examined the performance of four high-rate(0.75, 0.8, 0.889, 09412) LDPC coded OFDM in image transmission over Rayleigh fading channel. The high-rate of 0.9412 LDPC coded OFDM system obtained about 12dB gain over the OFDM at BER of $10^{-3}$ over Rayleigh fading channel. Also, the PSNR of code rate 0.9412 LDPC coded OFDM system at SNR=10dB is given by 18.8047dB where uncoded OFDM system gives 9.7303 dB.

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Performance of LDPC Product Code According to Error Factors on Holographic Data Storage System (홀로그래픽 데이터 저장장치 시스템에서 오류요인에 따른 LDPC 곱부호의 성능)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.5
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    • pp.3-7
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    • 2017
  • Holographic data storage system (HDSS) features short access times, high storage capacities, and fast transfer rates, since the data is recorded and read not by lines but by pages within a volume of holographic material. Burst error caused by physical impact on the high density storage system becomes very longer than that of conventional storage systems. This paper proposes an LDPC product code using two LDPC code to resolve burst error. When a total code rate is similar, the performance of two LDPC code having high code rate is better than that of one LDPC code having low code rate. Also, with error factors of two-dimensional intersysbol interference and misalignment, the proposed scheme can improve the performance in holographic data storage system.

LDPC-LDPC Product Code Using Modified Log-likelihood Ratio for Holographic Storage System (홀로그래픽 저장장치를 위한 수정된 로그-유사도비를 이용한 LDPC-LDPC 곱부호)

  • Jeong, Seongkwon;Lee, Jaejin
    • Journal of the Institute of Electronics and Information Engineers
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    • v.54 no.6
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    • pp.17-21
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    • 2017
  • Since holographic data storage has the advantage of high recording density and data transfer rate, it is a candidate for the next generation storage systems. However, Holographic data storage system is affected by interpage interference and two dimensional intersymbol interference. Also, burst error occurs by physical impact. In this paper, we propose an LDPC product code using modified log-likelihood ratio and extrinsic information to correct burst error and improve performance of holographic data storage. The performance of proposed LDPC product code is 0.5dB better than that of the conventional LDPC code.