• Title, Summary, Keyword: LDPC decoder

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A Novel LDPC Decoder with Adaptive Modified Min-Sum Algorithm Based on SNR Estimation (SNR 예측 정보 기반 적응형 Modified UMP-BP LDPC 복호기 설계)

  • Park, Joo-Yul;Cho, Keol;Chung, Ki-Seok
    • IEMEK Journal of Embedded Systems and Applications
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    • v.4 no.4
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    • pp.195-200
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    • 2009
  • As 4G mobile communication systems require high transmission rates with reliability, the need for efficient error correcting code is increasing. In this paper, a novel LDPC (Low Density Parity Check) decoder is introduced. The LDPC code is one of the most popular error correcting codes. In order to improve performance of the LDPC decoder, we use SNR (Signal-to-Noise Ratio) estimation results to adjust coefficients of modified UMP-BP (Uniformly Most Probable Belief Propagation) algorithm which is one of widely-used LDPC decoding algorithms. An advantage of Modified UMP-BP is that it is amenable to implement in hardware. We generate the optimal values by simulation for various SNRs and coefficients, and the values are stored in a look-up table. The proposed decoder decides coefficients of the modified UMP-BP based on SNR information. The simulation results show that the BER (Bit Error Rate) performance of the proposed LDPC decoder is better than an LDPC decoder using a conventional modified UMP-BP.

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Low-Complexity and High-Speed Multi-Size Circular Shifter With Benes Network Control Signal Optimization for WiMAX QC-LDPC Decoder (Benes 네트워크 제어 신호 최적화를 이용한 WiMAX QC-LDPC 복호기용 저면적/고속 Multi-Size Circular Shifter)

  • Kang, Hyeong-Ju
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.10
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    • pp.2367-2372
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    • 2015
  • One of various low-density parity-check(LDPC) codes that has been adopted in many communication standards due to its error correction ability is a quasi-cyclic LDPC(QC-LDPC) code, which leads to comparable decoder complexity. One of the main blocks in the QC-LCDC code decoder is a multi-size circular shifter(MSCS) that can perform various size rotation. The MSCS can be implemented with many structures, one of which is based on Banes network. The Benes network structure can perform the normal MSCS operation efficiently, but it cannot use the properties coming from specifications like rotation sizes. This paper proposesd a scheme where the Benes network structure can use the rotation size property with the modification of the control signal generation. The proposed scheme is applied to the MSCS of IEEE 802.16e WiMAX QC-LDPC decoder to reduce the number of MUXes and the critical path delay.

Low-Complexity Multi-Size Circular Shifter for QC-LDPC Decoder Based on Two Serial Barrel-Rotators (두 개의 직렬 Barrel-Rotator를 이용한 QC-LDPC 복호기용 저면적 Multi-Size Circular Shifter)

  • Kang, Hyeong-Ju
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.19 no.8
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    • pp.1839-1844
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    • 2015
  • The low-density parity-check(LDPC) code has been adopted in many communication standards due to its error correcting performance, and the quasi-cyclic LDPC(QC-LDPC) is widely used because of implementation easiness. In the QC-LDPC decoder, a cyclic-shifter is required to rotate data in various sizes. This kind of cyclic-shifters are called multi-size circular shifter(MSCS), and this paper proposes a low-complexity structure for MSCS. In the conventional serially-placed two barrel-rotators, the unnecessary multiplexers are revealed and removed, leading to low-complexity. The experimental results show that the area is reduced by about 12%.

Parallel LDPC Decoding on a Heterogeneous Platform using OpenCL

  • Hong, Jung-Hyun;Park, Joo-Yul;Chung, Ki-Seok
    • KSII Transactions on Internet and Information Systems (TIIS)
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    • v.10 no.6
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    • pp.2648-2668
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    • 2016
  • Modern mobile devices are equipped with various accelerated processing units to handle computationally intensive applications; therefore, Open Computing Language (OpenCL) has been proposed to fully take advantage of the computational power in heterogeneous systems. This article introduces a parallel software decoder of Low Density Parity Check (LDPC) codes on an embedded heterogeneous platform using an OpenCL framework. The LDPC code is one of the most popular and strongest error correcting codes for mobile communication systems. Each step of LDPC decoding has different parallelization characteristics. In the proposed LDPC decoder, steps suitable for task-level parallelization are executed on the multi-core central processing unit (CPU), and steps suitable for data-level parallelization are processed by the graphics processing unit (GPU). To improve the performance of OpenCL kernels for LDPC decoding operations, explicit thread scheduling, vectorization, and effective data transfer techniques are applied. The proposed LDPC decoder achieves high performance and high power efficiency by using heterogeneous multi-core processors on a unified computing framework.

Design Methodology of LDPC Codes based on Partial Parallel Algorithm (부분병렬 알고리즘 기반의 LDPC 부호 구현 방안)

  • Jung, Ji-Won
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.4 no.4
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    • pp.278-285
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    • 2011
  • This paper makes an analysis of the encoding structure and the decoding algorithm proposed by the DVB-S2 specification. The methods of implementing the LDPC decoder are fully serial decoder, the partially parallel decoder and the fully parallel decoder. The partial parallel scheme is the efficient selection to achieve appropriate trade-offs between hardware complexity and decoding speed. Therefore, this paper proposed an efficient memory structure for check node update block, bit node update block, and LLR memory.

A Study on High Speed LDPC Decoder Based on HSS (HSS기반의 고속 LDPC 복호기 연구)

  • Jung, Ji Won
    • The Journal of Korea Institute of Information, Electronics, and Communication Technology
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    • v.5 no.3
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    • pp.164-168
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    • 2012
  • LDPC decoder architectures are generally classified into serial, parallel and partially parallel architectures. Conventional method of LDPC decoding in general give rise to a large number of computation operations, mass power consumption, and decoding delay. It is necessary to reduce the iteration numbers and computation operations without performance degradation. This paper studies Horizontal Shuffle Scheduling (HSS) algorithm. In the result, number of iteration is half than conventional algorithm without performance degradation. Finally, this paper present design methodology of high-speed LDPC decoder and confirmed its throughput is up to about 600Mbps.

Architecture of an LDPC Decoder for DVB-S2 using reuse Technique of processing units and Memory Relocation (연산기와 메모리 재사용을 이용한 효율적인 DVB-S2 규격의 LDPC 복호기 구조)

  • Park Jae-Geun;Lee Chan-Ho
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.43 no.9
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    • pp.31-37
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    • 2006
  • Low-density parity-check (LDPC) codes are recently emerged due to its excellent performance. The standard for European high definition satellite digital video broadcast, DVB-S2 has adopted LDPC codes as a channel coding scheme. This paper proposes a DVB-S2 LDPC decoder architecture using a hybrid parity check matrix which is efficient in hardware implementation for both decoders and encoders. The hybrid H-matrices are constructed so that both the semi-random technique and the partly parallel structure can be applied to design encoders and decoders. Using the hybrid H-matrix scheme, the architecture of LDPC decoder for DVB-S2 can be very practical and efficient. In addition, we show a new Variable Node processor Unit (VNU) architecture to reuse the VNU for various code rates and optimized block memory placement to reuse. We design a DVB-S2 LDPC decoder of code rate 1/2 usng the proposed architecture. We estimate the performance of the DVB-S2 LDPC decoder and compare it with other decoders.

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 $0.18-{\mu}m$ 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.

A Design of Sign-magnitude based Multi-mode LDPC Decoder for WiMAX (Sign-magnitude 수체계 기반의 WiMAX용 다중모드 LDPC 복호기 설계)

  • Seo, Jin-Ho;Park, Hae-Won;Shin, Kyung-Wook
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.15 no.11
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    • pp.2465-2473
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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 including WiMAX and WLAN. A new design of DFU based on sign-magnitude arithmetic instead of two's complement arithmetic is proposed, resulting in 18% reduction of gate count for 96 DFUs array used in mobile WiMAX LDPC decoder. A multi-mode LDPC decoder for mobile WiMAX standard is designed using the proposed DFU. The LDPC decoder synthesized using a 0.18-${\mu}m$ CMOS cell library with 50 MHz clock has 268,870 gates and 71,424 bits RAM, and it is verified by FPGA implementation.

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.