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  • Title/Summary/Keyword: Low Density Parity Check

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A design of sign-magnitude based DFU block for LDPC decoder (LDPC 복호기를 위한 sign-magnitude 수체계 기반의 DFU 블록 설계)

  • Seo, Jin-Ho;Park, Hae-Won;Shin, Kyung-Wook
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2011.10a
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    • pp.415-418
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    • 2011
  • This paper describes a circuit-level optimization of DFU(decoding function unit) for LDPC decoder which is used in wireless communication systems such as WiMAX and WLAN. The conventional DFU which is based on min-sum decoding algorithm needs conversions between two's complement values and sign-magnitude values, resulting in complex hardware. In this paper, a new design of DFU that is based on sign-magnitude arithmetic is proposed to achieve a simplified circuit and high-speed operation.

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An analysis of Optimal Design Conditions of Multi-mode LDPC Decoder for IEEE 802.11n WLAN System (IEEE 802.11n WLAN용 다중모드 LPDC 복호기의 최적 설계조건 분석)

  • Park, Hae-Won;Na, Young-Heon;Shin, Kyung-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.2
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    • pp.432-438
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    • 2011
  • This paper describes an analysis of optimal design conditions of multi-mode LDPC(low density parity check) decoder which supports three block lengths (648, 1296, 1944) and four code rates (1/2, 2/3, 3/4, 5/6) for IEEE 802.11n WLAN system. A fixed-point model of LDPC decoder, which adopts min-sum algorithm and layered decoding scheme, is implemented using Matlab. From fixed-point simulation results for various bit-width parameters such as internal bit-width, integer/fractional part bit-widths, optimal design conditions and decoding performance of LDPC decoder are analyzed.

Generalization of Tanner′s Minimum Distance Bounds for LDPC Codes (LDPC 부호 적용을 위한 Tanner의 최소 거리 바운드의 일반화)

  • Shin Min Ho;Kim Joon Sung;Song Hong Yeop
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.29 no.10C
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    • pp.1363-1369
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    • 2004
  • LDPC(Low Density Parity Check) codes are described by bipartite graphs with bit nodes and parity-check nodes. Tanner derived minimum distance bounds of the regular LDPC code in terms of the eigenvalues of the associated adjacency matrix. In this paper we generalize the Tanner's results. We derive minimum distance bounds applicable to both regular and blockwise-irregular LDPC codes. The first bound considers the relation between bit nodes in a minimum-weight codeword, and the second one considers the connectivity between parity nodes adjacent to a minimum-weight codeword. The derived bounds make it possible to describe the distance property of the code in terms of the eigenvalues of the associated matrix.

An Improved Decoding Scheme of LCPC Codes (LCPC 부호의 개선된 복호 방식)

  • Cheong, Ho-Young
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.11 no.4
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    • pp.430-435
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    • 2018
  • In this paper, an improved decoding scheme for low-complexity parity-check(LCPC) code with small code length is proposed. The LCPC code is less complex than the turbo code or low density parity check(LDPC) code and requires less memory, making it suitable for communication between internet-of-things(IoT) devices. The IoT devices are required to have low complexity due to limited energy and have a low end-to-end delay time. In addition, since the packet length to be transmitted is small and the signal processing capability of the IoT terminal is small, the LCPC coding system should be as simple as possible. The LCPC code can correct all single errors and correct some of the two errors. In this paper, the proposed decoding scheme improves the bit error rate(BER) performance without increasing the complexity by correcting both errors using the soft value of the modulator output stage. As a result of the simulation using the proposed decoding scheme, the code gain of about 1.1 [dB] was obtained at the bit error rate of 105 compared with the existing decoding method.

Fast Implementation of the Progressive Edge-Growth Algorithm

  • Chen, Lin;Feng, Da-Zheng
    • ETRI Journal
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    • v.31 no.2
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    • pp.240-242
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    • 2009
  • A computationally efficient implementation of the progressive edge-growth algorithm is presented. This implementation uses an array of red-black (RB) trees to manage the layered structure of check nodes and adopts a new strategy to expand the Tanner graph. The complexity analysis and the simulation results show that the proposed approach reduces the computational effort effectively. In constructing a low-density parity check code with a length of 104, the RB-tree-array-based implementation takes no more 10% of the time required by the original method.

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A Low Density Parity Check Coding using the Weighted Bit-flipping Method (가중치가 부과된 Bit-flipping 기법을 이용한 LDPC 코딩)

  • Joh, Kyung-Hyun;Ra, Keuk-Hwan
    • 전자공학회논문지 IE
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    • v.43 no.4
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    • pp.115-121
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    • 2006
  • In this paper, we proposed about data error check and correction on channel transmission in the communication system. LDPC codes are used for minimizing channel errors by modeling AWGN Channel as a VDSL system. Because LDPC Codes use low density parity bit, mathematical complexity is low and relating processing time becomes shorten. Also the performance of LDPC code is better than that of turbo code in long code word on iterative decoding algorithm. This algorithm is better than conventional algorithms to correct errors, the proposed algorithm assigns weights for errors concerning parity bits. The proposed weighted Bit-flipping algorithm is better than the conventional Bit-flipping algorithm and we are recognized improve gain rate of 1 dB.

A Variable Rate LDPC Coded V-BLAST System (가변 부호화 율을 가지는 LDPC 부호화된 V-BLAST 시스템)

  • Noh, Min-Seok;Kim, Nam-Sik;Park, Hyun-Cheol
    • Proceedings of the IEEK Conference
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    • 2004.06a
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    • pp.55-58
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    • 2004
  • This this paper, we propose vertical Bell laboratories layered space time (V-BLAST) system based on variable rate Low-Density Parity Check (LDPC) codes to improve performance of receiver when QR decomposition interference suppression combined with interference cancellation is used over independent Rayleigh fading channel. The different rate LDPC codes can be made by puncturing some rows of a given parity check matrix. This allows to implement a single encoder and decoder for different rate LDPC codes. The performance can be improved by assigning stronger LDPC codes in lower layer than upper layer because the poor SNR of first detected data streams makes error propagation. Keeping the same overall code rates, the V-BLAST system with different rate LDPC codes has the better performance (in terms of Bit Error Rate) than with constant rate LDPC code in fast fading channel.

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A Multi-mode LDPC Decoder for IEEE 802.16e Mobile WiMAX

  • Shin, Kyung-Wook;Kim, Hae-Ju
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.12 no.1
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    • pp.24-33
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    • 2012
  • This paper describes a multi-mode LDPC decoder which supports 19 block lengths and 6 code rates of Quasi-Cyclic LDPC code for Mobile WiMAX system. To achieve an efficient implementation of 114 operation modes, some design optimizations are considered including block-serial layered decoding scheme, a memory reduction technique based on the min-sum decoding algorithm and a novel method for generating the cyclic shift values of parity check matrix. From fixed-point simulations, decoding performance and optimal hardware parameters are analyzed. The designed LDPC decoder is verified by FPGA implementation, and synthesized with a 0.18μm CMOS cell library. It has 380,000 gates and 52,992 bits RAM, and the estimated throughput is about 164 ~ 222 Mbps at 56 MHz@1.8 V.

Error correction using LDPC Code in SPCPC (SPCPC에서 LDPC부호를 이용한 오류 정정)

  • Kim, Sung-Man;Oh, Tae-Suk;Kim, Bum-Gon;Song, Hee-Keun;Kim, Yong-Cheol
    • Proceedings of the Korean Society of Broadcast Engineers Conference
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    • 2006.11a
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    • pp.229-232
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    • 2006
  • 본 논문은 AWGN 채널상의 Single Parity Check(SPC) 다차원 product부호에서 LDPC(Low Density Parity Check)부호를 이용한 오류 정정의 성능을 제시한다. 기존 방법인 터보 부호 방식을 이용한 오류 정정과 비교하여 LDPC부호가 갖는 장점을 기술하고 실험을 통해 LDPC 부호를 이용한 오류 정정 성능도 터보부호와 대등함을 보인다.

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A Design of ALT LDPC Codes Using Circulant Permutation Matrices (순환 치환 행렬을 이용한 ALT LDPC 부호의 설계)

  • Lee, Kwang-Jae
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.1
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    • pp.117-124
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    • 2012
  • In this paper, we propose a simple H parity check matrix from the CPM(circulant permutation matrix), which can easily avoid the cycle-4, and approach to flexible code rates and lengths. As a result, the operations of the submatrices will become the multiplications between several CPMs, the calculations of the LDPC(low density parity check) encoding could be simplest. Also we consider the fast encoding problem for LDPC codes. The proposed constructions could lead to fast encoding based on the simplest matrices operations for both regular and irregular LDPC codes.