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5th International Conference on Communication Systems and Network Technologies (CSNT)

作者： Kshirsagar, Ashlesha P. Kakde, Sandeep Chawhan, Manish Suryawanshi, Yogesh YC Coll Engn Dept Elect Engn Nagpur Maharashtra India RKNE Coll Dept Elect & Commun Engn Nagpur Maharashtra India

ISBN: (纸本)9781479917976

Many classes of high-performance Low-density parity check codes are based on parity check matrices composed of permutation sub matrices. The emulation-simulation framework further allows the algorithm and implementation to be iteratively redefined to improve the error floor performance of message passing decoder. Log-Like hood-Ratio (LLR) based Belief-Propagation (BP) algorithm is presented for Low Density Parity Check codes. Numerically accurate representation of check node update computation used in LLR-BP decoding is described. The implementation of Sum-Product algorithm (SPA) within Low Density Parity Check Code (LDPC) decoder is described in this paper and the correction term is used to improve the decoding performance of min-sum algorithm (MSA). Quantization and log-tanh function approximation in sum-product decoder strongly affect which absorbing set dominates in error floor region. For LDPC decoder, bit error rate (BER) decreases with increase in the signal to noise ratio.

关键词： Low-density parity check (LDPC) codes message-passing decoding error floor iterative decoder bit error rate

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Decoding algorithms for nonbinary LDPC codes over GF(q)

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IEEE TRANSACTIONS ON COMMUNICATIONS 2007年第4期55卷 633-643页

作者： Declercq, David Fossorier, Marc ETIS ENSEA UCP CNRSUMR 8051 F-95014 Cergy Pontoise France Univ Hawaii Dept Elect Engn Honolulu HI 96822 USA

In this letter, we address the problem of decoding nonbinary low-density parity-check (LDPC) codes over finite fields GF(q), with reasonnable complexity and good performance. In the first part of the letter, we recall the original belief propagation (BP) decoding algorithm and its Fourier domain implementation. We show that the use of tensor notations for the messages is very convenient for the algorithm description and understanding. In the second part of the. letter, we introduce a simplified decoder which is inspired by the min-sum decoder for binary LDPC codes. We called this decoder extended min-sum (EMS). We show that it is possible to greatly reduce the computationnal complexity of the check-node processing by computing approximate reliability measures with a limited number of values in a message. By choosing appropriate correction factors or offsets, we show that the EMS decoder performance is quite good, and in some cases better than the regular BP decoder. The optimal values of the factor and offset correction are obtained asymptotically with simulated density evolution. Our simulations on ultra-sparse codes over very-high-order fields show that nonbinary LDPC codes are promising for applications which require low frame-error rates for small or moderate codeword lengths. The EMS decoder is a good candidate for practical hardware implementations of such codes.

关键词： complexity reduction iterative decoder nonbinary low-density parity-check (LDPC) codes

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A Split-Decoding Message Passing Algorithm for Low Density Parity Check decoders

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JOURNAL OF SIGNAL PROCESSING SYSTEMS FOR SIGNAL IMAGE AND VIDEO TECHNOLOGY 2010年第3期61卷 329-345页

作者： Mohsenin, Tinoosh Baas, Bevan M. Univ Calif Davis Dept Elect & Comp Engn Davis CA 95616 USA

A Split decoding algorithm is proposed which divides each row of the parity check matrix into two or multiple nearly-independent simplified partitions. The proposed method significantly reduces the wire interconnect and decoder complexity and therefore results in fast, small, and high energy efficiency circuits. Three full-parallel decoder chips for a (2,048, 1,723) LDPC code compliant with the 10GBASE-T standard using MinSum normalized, MinSum Split-2, and MinSum Split-4 methods are designed in 65 nm, seven metal layer CMOS. The Split-4 decoder occupies 6.1 mm(2), operates at 146 MHz, delivers 19.9 Gbps throughput, with 15 decoding iterations. At 0.79 V, it operates at 47 MHz, delivers 6.4 Gbps and dissipates 226 mW. Compared to MinSum normalized, the Split-4 decoder chip is 3.3 times smaller, has a clock rate and throughput 2.5 times higher, is 2.5 times more energy efficient, and has an error performance degradation of 0.55 dB with 15 iterations.

关键词： Low density parity check LDPC iterative decoder Split-Row CMOS 65 nm 10GBASE-T VLSI

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Comparative study of turbo decoding techniques: An overview

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IEEE TRANSACTIONS ON VEHICULAR TECHNOLOGY 2000年第6期49卷 2208-2233页

作者： Woodard, JP Hanzo, L Univ Southampton Dept Elect & Comp Sci Southampton SO17 1BJ Hants England

In this contribution, we provide an overview of the novel class of channel codes referred to as turbo codes, which have been shown to be capable of performing close to the Shannon Limit. We commence with a brief discussion on turbo encoding, and then move on to describing the form of the iterative decoder most commonly used to decode turbo codes, We then elaborate on various decoding algorithms that can be used in an iterative decoder, and give an example of the operation of such a decoder using the so-called Soft Output Viterbi Algorithm (SOVA). Lastly, the effect of a range of system parameters is investigated in a systematic fashion, in order to gauge their performance ramifications.

关键词： .decoding algorithms Comparative Study frame length turbo coding Turbo Decoding iterative decoder Soft Output used to decode decoder using

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LW-Net: A Lightweight Network for Monocular Depth Estimation

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IEEE ACCESS 2020年 8卷 196287-196298页

作者： Feng, Cheng Zhang, Congxuan Chen, Zhen Li, Ming Chen, Hao Fan, Bingbing Nanchang Hangkong Univ Key Lab Nondestruct Testing Minist Educ Nanchang 330063 Jiangxi Peoples R China Chinese Acad Sci Inst Automat Beijing 100000 Peoples R China

Existing self-supervised monocular depth estimation methods usually explore increasingly large networks to achieve accurate estimation results. However, larger networks are more difficult to train and require more storage space. To balance the network size and the computational accuracy, we propose in this article a compact lightweight network for monocular depth estimation, named LW-Net. First, we construct a compact network by designing an iterative decoder with shared weights and a lightweight pyramid encoder. The proposed network includes significantly fewer parameters than most of the existing monocular depth estimation networks. Second, we exploit a self-supervised training strategy by combining the proposed LW-Net model with a pose network, and we then use a hybrid loss function to train the decoder and encoder separately. The proposed training strategy results in the LW-Net model achieving a better performance in terms of estimation accuracy than other methods. Finally, we respectively run the proposed LW-Net model on the KITTI and Make3D datasets to conduct a comprehensive comparison with several state-of-the-art methods. The experimental results demonstrate that our method performs the best in terms of computational accuracy while utilizing the fewest parameters. Specifically, the model parameters of our method are reduced by 46.6%, the time cost is decreased by 7.69%, and the frame rate is increased by 5.19% compared with the existing state-of-the-art method.

关键词： Estimation Decoding Computational modeling Cameras Task analysis Robots Training Monocular depth estimation lightweight self-supervised learning iterative decoder convolutional neural networks

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Multilevel turbo coding with short interleavers

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1998年第2期16卷 303-309页

作者： Herzberg, H Globespan Technol Inc Red Bank NJ 07701 USA

In this paper, the impact of the interleaver, embedded in the encoder for a parallel concatenated code, called the turbo code, is studied. The known turbo codes consist of long random interleavers, whose purpose is to reduce the value of the error coefficients, It is shown here that an increased minimum Hamming distance can be obtained by using a structured interleaver, For low bit-error rates (BER's), we show that the performance of turbo codes with a structured interleaver is better than that obtained with a random interleaver, Another important advantage of the structured interleaver is the short length required, which yields a short decoding delay and reduced decoding complexity (in terms of memory), We also consider the use of turbo codes as component codes in multilevel codes, Powerful coding structures that consist of two component codes are suggested, Computer simulations are performed in order to evaluate the reduction in coding gain due to suboptimal iterative decoding, From the results of these simulations we deduce that the degradation in the performance (due to suboptimal decoding) is very small.

关键词： interleaver iterative decoder multilevel code multistage decoder turbo code

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On the Diversity and Coded Modulation Design of Fluid Antenna Systems

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IEEE TRANSACTIONS ON WIRELESS COMMUNICATIONS 2024年第3期23卷 2082-2096页

作者： Psomas, Constantinos Kraidy, Ghassan M. Wong, Kai-Kit Krikidis, Ioannis Univ Cyprus Dept Elect & Comp Engn CY-1678 Nicosia Cyprus Dept Elect Syst Norwegian Univ Sci & Technol N-7034 Trondheim Norway UCL Dept Elect & Elect Engn London WC1E 6BT England

Reconfigurability is a desired characteristic of future communication networks. From a transceiver's standpoint, this can be materialized through the implementation of fluid antennas (FAs). An FA consists of a dielectric holder, in which a radiating liquid moves between pre-defined locations (called ports) that serve as the transceiver's antennas. Due to the nature of liquids, FAs can practically take any size and shape, making them both flexible and reconfigurable. In this paper, we deal with the outage probability of FAs under general fading channels, where a port is scheduled based on selection combining. An analytical framework is provided for the performance with and without errors due to post-scheduling delays. We show that although FAs achieve maximum diversity, this cannot be realized in the presence of delays. Hence, a linear prediction scheme is proposed that overcomes delays and restores the lost diversity by predicting the next scheduled port. Moreover, we design space-time coded modulations that exploit the FA's sequential operation with space-time rotations and code diversity. The derived expressions for the pairwise error probability and average word error rate give an accurate estimate of the performance. We illustrate that the proposed design attains maximum diversity, while keeping a low-complexity receiver, thereby confirming the feasibility of FAs.

关键词： Fluid antennas outage probability outdated channels diversity space-time rotations coded modulation iterative decoder

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A new semiblind scheme based on second and fourth order statistics for decoding of Space-Time data in time selective MIMO channels

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WIRELESS PERSONAL COMMUNICATIONS 2008年第2期47卷 193-205页

作者： Bhatnagar, Manav R. Vishwanath, R. Univ Oslo UniK Univ Grad Ctr N-2027 Kjeller Norway Univ Calif Davis Dept Elect & Comp Engn Davis CA 95616 USA

In this paper we propose a novel semiblind scheme based on second and fourth order statistics of Space-Time data in time varying MIMO channels. This scheme combines a new blind estimator of frequency offsets and an iterative decoder. Space-Time Codes have a periodic property which is used to find a simple and efficient blind estimator of carrier offsets. The iterative decoder is a data aided decoder which provides the best estimates of channel, noise co-variance and S-T data in its category. As a result of this the new semiblind scheme performs very efficiently in time-selective channels and is able to reduce the training overhead required by the data-aided estimators to a large extent, and increase the effective throughput.

关键词： Space-Time code iterative decoder frequency offsets

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SISO APP Searches in Lattices With Tanner Graphs

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IEEE TRANSACTIONS ON INFORMATION THEORY 2012年第5期58卷 2672-2688页

作者： Ionescu, Dumitru Mihai Zhu, Haidong Nokia Res Ctr San Diego CA USA

An efficient, low-complexity, soft-output detector for general lattices is presented, based on their Tanner graph (TG) representations. Closest-point searches in lattices can be performed as nonbinary belief propagation on associated TGs;soft-information output is naturally generated in the process;the algorithm requires no backtrack (cf. classic sphere decoding), and extracts extrinsic information. A lattice's coding gain enables equivalence relations between lattice points, which can be thereby partitioned in cosets. Total and extrinsic a posteriori probabilities at the detector's output further enable the use of soft detection information in iterative schemes. The algorithm is illustrated via two scenarios that transmit a 32-point, uncoded super-orthogonal (SO) constellation for multiple-input multiple-output (MIMO) channels, carved from an 8-dimensional nonorthogonal lattice D-4 circle plus D-4 it achieves maximum likelihood performance in quasistatic fading;and, performs close to interference-free transmission, and identically to list sphere decoding, in independent fading with coordinate interleaving and iterative equalization and detection. Latter scenario outperforms former despite absence of forward error correction coding-because the inherent lattice coding gain allows for the refining of extrinsic information. The lattice constellation is the same as the one employed in the SO space-time trellis codes first introduced for 2 x 2 MIMO by Ionescu et al., then independently by Jafarkhani and Seshadri. Algorithmic complexity is log-linear in lattice dimensionality versus cubic in classic sphere decoders.

关键词： Belief propagation closest lattice point search complexity iterative decoder MIMO soft-output sphere decoder Tanner graph

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A 25MHz Sign and Magnitude Converter for Analog Current Mode iterative decoders

A 25MHz Sign and Magnitude Converter for Analog Current Mode...

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IEEE Asia Pacific Conference on Circuits and Systems

作者： Ming-Yam Lo Wing-Hung Ki Wai-Ho Mow Department of Electronic and Computer Engineering The Hong Kong University of Science and Technology

A 25MHz low-power sign and magnitude (SAM) converter for processing bi-directional currents is proposed It converts the lowest current of ±1μA in less than 40ns, and does not require any static bias currents. Th... 详细信息

ISBN: (纸本)9781424474547

关键词： Analog decoder Current mode iterative decoder Magnitude Sign

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