• Title/Summary/Keyword: LDPC Code

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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.

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

  • Jang, Eun-Young
    • The Journal of the Korea institute of electronic communication sciences
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    • v.12 no.4
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    • pp.569-574
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    • 2017
  • In order to transmit information in a channel environment in which noise exists, a coding technique of information is required. One of the coding techniques used for error detection and correction close to the Shannon limit is Low Density Parity Code(LDPC). 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.

Further Results on Performance of LDPC coded IM-OFDM-QOS System

  • Kim, Hyeongseok;Kim, Jeongchang
    • Journal of Broadcast Engineering
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    • v.24 no.7
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    • pp.1221-1227
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    • 2019
  • This paper describes a low-density parity-check (LDPC) coded index modulated orthogonal frequency division multiplexing with quasi-orthogonal sequence (IM-OFDM-QOS) and provides performance evaluations of the proposed system. By using QOS as the spreading code, IM-OFDM-QOS scheme can improve the reception performance than IM-OFDM-SS scheme for a given data rate. On the other hand, LDPC code is widely used to the latest wireless communication systems as forward error correction (FEC) scheme and has Shannon-limit approaching performance. Therefore, by applying LDPC code to IM-OFDM-QOS system as FEC scheme, the reception performance can be further improved. Simulation results show that significant signal-to-noise ratio (SNR) gains can be obtained for LDPC coded IM-OFDM-QOS system compared to the LDPC coded IM-OFDM-SS system and the SNR gain increases with the higher code rate.

Low Density Parity Check Codes for Hybrid ARQ System

  • Kim, Woo-Tae;Kim, Jeong-Goo;Joo, Eon-Kyeong
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.4C
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    • pp.370-378
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    • 2007
  • The most appropriate low density parity check (LDPC) code for hybrid automatic repeat request (HARQ) system suitable for future multimedia communication systems is presented in this paper. HARQ system with punctured LDPC code is investigated at first. And two transmission schemes with parallel concatenated LDPC code are also presented and their performances are analyzed according to the various values of mean column weight (MCW). As a result, the parallel concatenated LDPC code with the diversity effect of information bit is considered to be more appropriate for HARQ system considering the throughput as well as error performance.

Performance of Noise-Predictive Turbo Equalization for PMR Channel (수직자기기록 채널에서 잡음 예측 터보 등화기의 성능)

  • Kim, Jin-Young;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.10C
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    • pp.758-763
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    • 2008
  • We introduce a noise-predictive turbo equalization using noise filter in perpendicular magnetic recording(PMR) channel. The noise filter mitigates the colored noise in high-density PMR channel. In this paper, the channel detectors used are SOVA (Soft Output Viterbi Algorithm) and BCJR algorithm which proposed by Bahl et al., and the outer decoder used is LDPC (Low Density Parity Check) code that is implemented by sum-product algorithm. Two kinds of LDPC codes are experimented. One is the 0.5Kbyte (4336,4096) LDPC code with the code rate of 0.94, and the other is 1Kbyte (8432,8192) LDPC code with the code rate of 0.97.

A Study on Turbo Equalization for MIMO Systems Based on LDPC Codes (MIMO 시스템에서 LDPC 부호 기반의 터보등화 방식 연구)

  • Baek, Chang-Uk;Jung, Ji-Won
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.41 no.5
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    • pp.504-511
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    • 2016
  • In this paper, MIMO system based on turbo equalization techniques which LDPC codes were outer code and space time trellis codes (STTC) were employed as an inner code are studied. LDPC decoder and STTC decoder are connected through the interleaving and de-interleaving that updates each other's information repeatedly. In conventional turbo equalization of MIMO system, BCJR decoder which decodes STTC coded bits required two-bit wise decoding processing. Therefore duo-binary turbo codes are optimal for MIMO system combined with STTC codes. However a LDPC decoder requires bit unit processing, because LDPC codes can't be applied to these system. Therefore this paper proposed turbo equalization for MIMO system based on LDPC codes combined with STTC codes. By the simulation results, we confirmed performance of proposed turbo equalization model was improved about 0.6dB than that of conventional LDPC codes.

Performance of LDPC with Message-Passing Channel Detector for Perpendicular Magnetic Recording Channel (수직자기기록 채널에서 LDPC를 이용한 메시지 전달 방식의 채널 검출 성능비교)

  • Park, Dong-Hyuk;Lee, Jae-Jin
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.33 no.4C
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    • pp.299-304
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    • 2008
  • For perpendicular magnetic recording channels, it is hard to expect improving the performance by using the PRML or NPML. Hence, we exploit LDPC code to improve the performance. In this paper, we examine a single message-passing detector/decoder matched to the combination of a perpendicular magnetic recording channel detector and an LDPC code decoder. We examine the performance of channel iteration with joint LDPC code on perpendicular magnetic recording channel, and simplify the complexity of the message-passing detector algorithm.

LDPC Generation and Decoding concatenated to Viterbi Decoder based on Sytematic Convolutional Encoder (길쌈부호기를 이용한 LDPC 패리티검사 행렬생성 및 비터비 복호 연계 LDPC 복호기)

  • Lee, Jongsu;Hwang, Eunhan;Song, Sangseob
    • Smart Media Journal
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    • v.2 no.2
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    • pp.39-43
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    • 2013
  • In this paper, we suggest a new technique for WPC parity-check matrix (H-matrix) generation and a corresponding decoding process. The key idea is to construct WPC H-matrix by using a convolutional encoder. It is easy to have many different coderates from a mother code with convolutional codes. However, it is difficult to have many different coderates with LDPC codes. Constructing LDPC Hmatrix based on a convolutional code can easily bring the advantage of convolutional codes to have different coderates. Moreover, both LDPC and convolutional decoding algorithms can be applied altogether in the decoding part. This process prevents the performance degradation of short-length WPC code.

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Design and Performance Evaluation of Multilevel LDPC Codes (다중 레벨 LDPC 부호의 설계 및 성능 분석)

  • ;Yu Yi;Jia Hou
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.15 no.1
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    • pp.51-59
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    • 2004
  • We design multilevel coding(MLC) with a semi bit-interleaved coded modulation(BICM) scheme based on low density parity check(LDPC) codes. Different from traditional designs, we joint the MLC and BICM together by using the Gray mapping, which can transmit the multimedia data over several equivalent channels with different code rates. To get a good performance from signal-to-noise ratio(SNR) very close to the capacity of the additive white Gaussian noise(AWGN) channel, random regular LDPC code and a simple semi-algebra LDPC(SA-LDPC) code are discussed in MLC with parallel independent decoding(PID). Finally, the numerical results demonstrate that the proposed scheme could achieve both power and bandwidth efficiency for multimedia communication system.