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Residual-Decaying-Based Informed Dynamic scheduling for belief-propagation decoding of LDPC Codes

IEEE ACCESS 2019年 7卷 23656-23666页

作者： Zhang, Huilian Chen, Shaoping South Cent Univ Nationalities Hubei Key Lab Intelligent Wireless Commun Wuhan 430074 Hubei Peoples R China

belief-propagation (BP) algorithm and its variants are well-established methods for iterative decoding of LDPC codes. Among them, residual belief-propagation (RBP), which is the most primitive and representative informed dynamic scheduling (IDS) strategy, can significantly accelerate the convergence speed. However, RBP decoding suffers from a poor convergence error-rate performance due to its greedy property, which is one of the challenging issues in the design of IDS strategies. To tackle this problem, a novel IDS scheme, namely residual-decaying-based residual belief-propagation (RD-RBP) algorithm, is presented in this paper. In RD-RBP, a decaying mechanism is introduced to manipulate the residuals of those check-to-variable messages, preventing the decoding resources from being unreasonably occupied by a small group of edges in the Tanner graph. The greediness is therefore alleviated and better performance of convergence error-rate is achieved. Besides, a two-stage scheduling scheme combining prior-art variable-node and variable-to-check-edge RBP (V-VCRBP) with RD-RBP, named V-VC-RD-RBP, is proposed for achieving both fast convergence speed and a low convergence error-rate. The simulation results validate the advantages of the proposed schemes.

关键词： LDPC codes belief-propagation decoding informed dynamic scheduling residual-decaying greediness

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Variable-Node-Based belief-propagation decoding With Message Pre-Processing for NAND Flash Memory

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IEEE ACCESS 2019年 7卷 58638-58653页

作者： Liu, Xingcheng Yang, Guojun Chen, Xuechen Sun Yat Sen Univ Sch Elect & Informat Technol Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Sch Informat Sci Xinhua Coll Guangzhou 510520 Guangdong Peoples R China

With the fast development of non-volatile storage technology, NAND flash memory faces more and more challenges such as data reliability and lifetime. To overcome the issue of the reliability, low-density parity-check (LDPC) codes are considered as a main candidate of error-correction-codes (ECCs) for NAND flash storages. However, conventional soft decoding algorithms for LDPC codes suffer from the drawback of slow convergence speed, which increases the decoding latency. For achieving fast convergence speed, a variable-node-based belief-propagation with message pre-processing (VNBP-MP) decoding algorithm for binary LDPC codes and a non-binary VNBP-MP (NVNBP-MP) decoding algorithm for non-binary LDPC codes are proposed. Both of the algorithms utilize the characteristics of the NAND flash channel to perform the message pre-processing operations. In theory, the propagation of unreliable messages can be effectively prevented and the propagation of reliable messages can be speeded up. To further improve the decoding convergence, the treatment for oscillating variable nodes is considered after the message pre-processing operations. The simulation results also show that the proposed algorithms both have a noticeable improvement in convergence speed and latency, without compromising error-correction performance, compared with the existing soft decoding algorithms.

关键词： NAND flash memory low-density parity-check (LDPC) code message pre-processing belief-propagation decoding error-correction performance

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Informed Fixed Scheduling for Faster Convergence of Shuffled belief-propagation decoding

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IEEE COMMUNICATIONS LETTERS 2017年第1期21卷 32-35页

作者： Aslam, Chaudhry Adnan Guan, Yong Liang Cai, Kui Han, Guojun Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Singapore Univ Technol & Design Dept Sci Singapore 487372 Singapore Guangdong Univ Technol Guangzhou 510006 Guangdong Peoples R China

A novel informed fixed scheduling (IFS) scheme for shuffled belief-propagation (BP) decoding of binary low-density parity-check (LDPC) code is introduced to improve the BP decoding convergence. The IFS finds an appropriate order of variable nodes in accordance with the number of updated neighbors in the code graph, ensuring that the maximum number of latest message updates is utilized within a single iteration. This allows the utilization of most reliable message updates in a timely manner, leading to faster error-rate convergence. Simulation results show that the proposed IFS scheme improves the convergence speed of BP decoder by up to 20% for regular LDPC codes and 45% for irregular LDPC codes, without affecting the errorrate performance, at medium-to-high signal-to-noise ratio over binary-input additive white Gaussian noise channel.

关键词： LDPC codes scheduling scheme belief-propagation decoding convergence speed decoding complexity

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Enhanced Informed Dynamic BP decoding Scheduling Strategies for 5G NR LDPC Codes 96

Enhanced Informed Dynamic BP Decoding Scheduling Strategies ...

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IEEE 96th Vehicular Technology Conference (VTC-Fall)

作者： Chang, Tofar C-Y Lee, I-Hsiang Wang, Pin-Han Weng, Jian-Jia Su, Yu T. Natl Taipei Univ Technol Dept Elect Engn Taipei Taiwan MediaTek Inc Hsinchu Taiwan Natl Taiwan Ocean Univ Dept Elect Engn Keelung Taiwan Natl Yang Ming Chiao Tung Univ Dept Elect & Comp Engn Hsinchu Taiwan

ISBN: (纸本)9781665454681

We present an enhanced informed dynamic scheduling (IDS) strategy to avoid propagations of unreliable messages in the residual belief-propagation (RBP) algorithm for decoding low-density parity-check (LDPC) codes. To reduce the resource needed for updating the degree-one variable nodes (VNs) in an RBP-based algorithm for decoding 5G New Radio (NR) LDPC codes, we further introduce a process consisting of several simple procedures for managing the resource consumption. Simulation results demonstrate that our RBP algorithm based on the proposed IDS strategy outperforms existing RBP-based algorithms at the early decoding iterations. By using our degree-one VN resource managing approach, the performance of both the proposed and the existing decoders is significantly improved in decoding the 5G NR codes.

关键词： LDPC codes belief-propagation decoding informed dynamic scheduling decoding resource management 5G NR

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A Low Latency decoding Algorithm for Grouping Variable Nodes on TLC NAND Flash Devices

A Low Latency Decoding Algorithm for Grouping Variable Nodes...

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IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC)

作者： Guo, Ting Liu, Xingcheng Sun Yat Sen Univ Sch Elect & Informat Technol Guangzhou 510006 Guangdong Peoples R China Sun Yat Sen Univ Xinhua Coll Sch Informat Sci Guangzhou 510520 Guangdong Peoples R China

ISBN: (纸本)9781728102863

The intra-cell characteristics of TLC NAND Flash memory are analyzed based on the channel model employed in this paper. In order to solve the read latency and the reliability degradation, caused by LDPC soft decision decoding and by the increase of flash storage density, respectively, a dynamic block grouping approach is proposed to divide all variable nodes (VNs) into three sub-blocks. To exploit the reliability of the VNs within the three sub-blocks, different update operations are performed in order. Moreover, the decoding latency is reduced with fewer iterations for the VNs in the most reliable sub-block, at the same time, the priority for updating of the reliable sub-block and the timely processing of the VNs with low-information have more useful information transmitted in the iterative decoding process, resulting in the improved convergency speed. In quantity, our simulation results show that the proposed algorithm improves the convergency rate by about 28.6% and reduces the average number of iterations by around 27.7%, compared with the VNBP-MP algorithm without compromising the error correction performance on the TLC NAND Flash devices.

关键词： TLC NAND Flash LDPC code flash model belief-propagation decoding

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Antipodal Detection and decoding for Large Multi-User MIMO with Reduced Base-Station Antennas

Antipodal Detection and Decoding for Large Multi-User MIMO w...

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IEEE Global Telecommunications Conference (GC Wkshps)

作者： Husmann, Christopher Tafazolli, Rahim Nikitopoulos, Konstantinos Univ Surrey Inst Commun Syst 5G Innovat Ctr Guildford Surrey England

ISBN: (纸本)9781538649206

To avoid unnecessarily using a massive number of base station antennas for supporting a large number of users in spatially multiplexed multi-user MIMO systems, optimal detection methods are required to demultiplex the mutually interfering information streams. Sphere decoding (SD) can achieve this, but its complexity and latency becomes impractical for large MIMO systems. Low complexity detection solutions such as linear detectors (e.g., MMSE) or likelihood ascendant search (LAS) approaches, have significantly lower latency requirements than SD but their achievable throughput is far from optimal. This work presents the concept of Antipodal detection and decoding, that can deliver very high throughput with practical latency requirements, even in systems where the number of user antennas reaches the number of base station antennas. The Antipodal detector either results in a highly reliable vector solution, or it does not find a vector solution at all (i.e., it results in an erasure), skipping the heavy processing load related to finding vector solutions that have a very high likelihood to be erroneous. Then, a belief-propagation-based decoder is proposed, that restores these erasures and further corrects remaining erroneous vector solutions. We show that for 32 x 32, 64-QAM modulated systems, and for packet error rates below 10 %, Antipodal detection and decoding requires 9 dB less transmitted power than systems employing soft MMSE or LAS detection and LDPC decoding with similar complexity requirements. For the same scenario, our Antipodal method achieves practical throughput gains of more than 50% compared to soft MMSE and soft LAS-based methods.

关键词： MIMO systems belief-propagation decoding spatial multiplexing

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An Improved Variable-Node-Based BP decoding Algorithm for NAND Flash Memory 18

An Improved Variable-Node-Based BP Decoding Algorithm for NA...

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18th IEEE International Conference on Communication Technology (IEEE ICCT)

作者： Yang, Guojun Liu, Xingcheng Chen, Xuechen Wang, Zhongfeng Sun Yat Sen Univ Sch Elect & Informat Technol Guangzhou Guangdong Peoples R China Nanjing Univ Sch Elect Sci & Engn Nanjing Jiangsu Peoples R China

ISBN: (纸本)9781538676356

To solve the problems of the data reliability for NAND flash storages, a variable-node-based belief-propagation with message pre-processing (VNBP-MP) decoding algorithm for binary low-density parity-check (LDPC) codes is proposed. The major feature is that, by making use of the characteristics of the NAND flash channel, the proposed algorithm performs the message pre-processing (MP) scheme to effectively prevent the propagation of unreliable messages and speed up the propagation of reliable messages. To further speed up the decoding convergence, the treatment for oscillating variable nodes (VNs) is considered after the MP scheme being employed. Simulation results show that the proposed VNBP-MP algorithm has a noticeable improvement in convergence speed without compromising the error-correction performance, compared with the existing algorithms.

关键词： NAND flash memory LDPC code message preprocessing belief-propagation decoding error-correction performance

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Decision-Directed Retention-Failure Recovery With Channel Update for MLC NAND Flash Memory

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IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS I-REGULAR PAPERS 2018年第1期65卷 353-365页

作者： Aslam, Chaudhry Adnan Guan, Yong Liang Cai, Kui Nanyang Technol Univ Sch Elect & Elect Engn Singapore 639798 Singapore Singapore Univ Technol & Design Sci & Math Cluster Singapore 487372 Singapore

To recover from the retention noise induced errors in NAND flash memory, a retention-aware belief-propagation (RABP) decoding scheme for low-density parity-check codes is introduced. The RABP is a two-stage decoding scheme in which the memory cell's charge-loss effect is systematically compensated. In RABP decoding, instead of read retries for data recovery, the probable victim cells are first determined with the help of read-back voltage signal and the decoded bit decisions. Then, for such suspected victim cells, their log-likelihood-ratio regions are modified in such a way as to absorb the effect of cell voltage downshift caused by retention noise, and then a second round of belief-propagation (BP) decoding is performed afresh, often with decoding failure recovery. Furthermore, leveraging on the RABP decoded bit-error pattern, an RABP assisted channel update (RABP-CU) algorithm is proposed which re-estimates the latest cell voltage distribution parameters without incurring new memory sensing operations. This is achieved by minimizing the mean squared error between the measured and predicted bit error/erasure values. Through simulations, it is shown that the RABP decoder increases the retention time limit by up to 70% compared with single round of BP decoding. The proposed RABP-CU algorithm further extends the data retention time.

关键词： NAND flash memory data retention noise retention-failure recovery flash channel estimation voltage distribution belief-propagation decoding error-rate performance

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Doubly multistage decoding of low-density parity-check codes over Z_2m

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IET COMMUNICATIONS 2012年第15期6卷 2341-2350页

作者： Yuan, H. Armand, M. A. Natl Univ Singapore Dept Elect & Comp Engn Singapore 117576 Singapore

A doubly multistage decoder (DMD) for low-density parity-check codes over Z(2m), m > 1, which fuses the multistage decoding approaches of Armand et al. and Varnica et al., is proposed. Two variants of the DMD are considered. The first (respectively, second) performs belief-propagation (BP) [respectively, offset min-sum (OMS)] decoding in each decoding stage and is referred to as DMD - BP (respectively, DMD - OMS). For the moderate-length codes considered in this study, the computer simulations show the DMD - BP (respectively, DMD - OMS) achieving coding gains of up to 0.43 dB (respectively, 0.67 dB) over standard BP decoding at a bit error rate of 10(-6) on an additive-white-Gaussian-noise channel, while requiring significantly less computational power. Remarkably, DMD - OMS outperforms DMD - BP, yet has lower computational complexity than DMD - BP. Snapshots of the log-likelihood ratio densities of the decoded bits midway through the decoding process explain the superiority of the DMD over standard BP decoding.

关键词： low-density parity-check code doubly multistage decoding decoding parity check codes additive-white-Gaussian-noise channel offset min-sum Codes Information theory computer simulation AWGN channels log-likelihood ratio error statistics belief-propagation decoding bit error rate moderate-length code Other topics in statistics

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Pseudocodeword Weights for LDPC Codes under Differential PSK Transmission over the Noncoherent AWGN Channel

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IEEE TRANSACTIONS ON COMMUNICATIONS 2011年第5期59卷 1218-1223页

作者： Mo, Elisa Armand, Marc A. Natl Univ Singapore Dept Elect & Comp Engn Singapore Singapore

This Letter considers the finite-length analysis of iterative decoding of low-density parity-check codes under differential binary-phase-shift-keying (DBPSK) and differential quadrature-phase-shift-keying (DQPSK) over the noncoherent additive-white-Gaussian-noise channel. Specifically, we derive the weight of the pseudocodewords of a Tanner graph under these signaling schemes and use them to explain the difference in error performance between coded DBPSK and coded DQPSK.

关键词： belief-propagation decoding differential phase-shift-keying graph-cover decoding iterative decoding pseudocodewords spectral thinning

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