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An Improved decoding Algorithm for Finite-Geometry LDPC Codes

IEEE TRANSACTIONS ON COMMUNICATIONS 2009年第2期57卷 302-306页

作者： Ngatched, Telex Magloire Nkouatchah Takawira, Fambirai Bossert, Martin Univ KwaZulu Natal Sch Elect Elect & Comp Engn ZA-4041 Durban South Africa Univ Ulm Dept Telecommun & Appl Informat Theory D-89081 Ulm Germany

In this letter, an improved bit-flipping decoding algorithm for high-rate finite-geometry low-density parity-check (FG-LDPC) codes is proposed. Both improvement in performance and reduction in decoding delay are observed by flipping multiple bits in each iteration. Our studies show that the proposed algorithm achieves an appealing tradeoff between performance and complexity for FG-LDPC codes.

关键词： Belief propagation algorithm bit-flipping (BF) decoding algorithms low-density parity-check (LDPC) codes

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Modified Log-MAP Algorithm for Simplified decoding of Turbo and Turbo TCM Codes

Modified Log-MAP Algorithm for Simplified Decoding of Turbo ...

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69th IEEE Vehicular Technology Conference

作者： Papaharalabos, Stylianos Sybis, Michal Tyczka, Piotr Mathiopoulos, P. Takis Natl Observ Athens ISARS Palea Penteli 15236 Greece Poznan Univ Tech Chair Wireless Commun PL-60965 Poznan Poland

ISBN: (纸本)9781424425167

A novel method for approximating the optimal max(star) operator in Log-MAP decoding of turbo and turbo trellis-coded modulation (TTCM) codes is presented. The max(star) operation is performed on n>2 rather than on only two inputs, as it is in the conventional approach. The approximation uses a very simple max operation and a look-up table (LUT) with only eight stored values. Complexity comparison reveals a significant reduction in the number of operations required per decoding step for the presented approximation, as compared with the conventional Log-MAP decoding. Performance evaluation results are presented for both turbo and TTCM codes, showing the near-optimal performance of the novel approach.

关键词： turbo codes turbo trellis-coded modulation decoding algorithms

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Bias, optimal linear estimation, and the differences between open-loop simulation and closed-loop performance of spiking-based brain-computer interface algorithms

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NEURAL NETWORKS 2009年第9期22卷 1203-1213页

作者： Chase, Steven M. Schwartz, Andrew B. Kass, Robert E. Carnegie Mellon Univ Dept Stat Pittsburgh PA 15203 USA Univ Pittsburgh Dept Neurobiol Pittsburgh PA 15260 USA Univ Pittsburgh Ctr Neural Basis Cognit Pittsburgh PA 15260 USA

The activity of dozens of simultaneously recorded neurons can be used to control the movement of a robotic arm or a Cursor on a computer screen This motor neural prosthetic technology has Spurred an increased interest in the algorithms by which motor intention can be inferred. The simplest of these algorithms is the population vector algorithm (PVA). where the activity of each cell is used to weight a vector pointing in that neuron's preferred direction Off-line, it is possible to show that more complicated algorithms, Such as the optimal linear estimator (OLE). can yield substantial improvements in the accuracy of reconstructed hand movements over the PVA We call this open-loop performance In contrast, this performance difference may not be present in closed-loop, on-line control The obvious difference between open and closed-loop control is the ability to adapt to the specifics of the decoder in use at the time In order to predict performance gains that an algorithm may yield in closed-loop control. it is necessary to build a model that captures aspects of this adaptation process. Here we present a framework for modeling the closed-loop performance of the PVA and the OLE. Using both simulations and experiments. we show that (1) the performance gain with certain decoders can be far less extreme than predicted by off-line results, (2) that subjects are able to compensate for certain types of bias in decoders, and (3) that care must be taken to ensure that estimation error does not degrade the performance of theoretically optimal decoders. (C) 2009 Elsevier Ltd All rights reserved.

关键词： Neural prosthetics decoding algorithms Brain-machine interface

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Fast decoding of the p-ary first-order Reed-Muller codes based on Jacket transform

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IEICE TRANSACTIONS ON FUNDAMENTALS OF ELECTRONICS COMMUNICATIONS AND COMPUTER SCIENCES 2008年第3期E91A卷 901-904页

作者： Lee, Moon Ho Borissov, Yuri L. Chonbuk Natl Univ Inst Informat & Commun Jeonju 561756 South Korea Bulgarian Acad Sci Inst Math & Informat BU-1113 Sofia Bulgaria

We propose a fast decoding algorithm for the p-ary first-order Reed-Muller code guaranteeing correction of up to left perpendicularn/4 sin(p-1/2p)right perpendicular errors and having complexity proportional to n log n, where n = p(m) is the code length and p is an odd prime. This algorithm is an extension in the complex domain of the fast Hadamard transform decoding algorithm applicable to the binary case.

关键词： p-ary first-order Reed-Muller codes decoding algorithms Jacket matrix

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Bayesian analysis of interference cancellation for Alamouti multiplexing

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IEEE TRANSACTIONS ON INFORMATION THEORY 2008年第10期54卷 4755-4761页

作者： Sirianunpiboon, Songsri Calderbank, A. Robert Howard, Stephen D. Def Sci & Technol Org Edinburgh 5111 Australia Princeton Univ Princeton NJ 08544 USA

Space-time codes built out of Alamouti components have been adopted in wireless standards such as UNITS, IEEE 802.11n, and IEEE 802.16, where they facilitate higher data rates through multiplexing of parallel data streams and the addition of two or more antennas at the receiver that perform interference cancellation. This correspondence provides new theoretical insight into different algorithms for interference cancellation through a Bayesian analysis that expresses performance as a function of signal-to-noise ratio (SNR) in terms of the "angles" between different space-time coded data streams.

关键词： Alamouti code Bayesian analysis decoding algorithms interference cancellation quaternion arithmetic space-time block codes

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QC-LDPC codes and their Performance on Power Line Communications Channel

QC-LDPC codes and their Performance on Power Line Communicat...

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IEEE International Symposium on Power Line Communications and Its Applications

作者： Andreadou, Nikoleta Pavlidou, Fotini-Niovi Aristotle Univ Thessaloniki Dept Elect & Comp Engn Telecommun Div Thessaloniki 54124 Greece

ISBN: (纸本)9781424437917

In this paper Low Density Parity Check Codes (LDPC) are introduced in the Power Line Communications Channel (PLC). We investigate how different decoding algorithms, which are applied on LDPC codes, affect the system's performance. Therefore, an iterative belief propagation decoding algorithm as well as a proposed variation of the original bit flipping algorithm are exploited. In addition, a hybrid technique combining these two algorithms is proposed. Irregular LDPC codes of various code rates are studied. Specifically, the cases of 1/2, 1/3, 2/3, 3/4 and 4/5 code rates are investigated. Regarding the irregular LDPC codes, they are constructed in a Quasi-Cyclic form. The system's performance is expressed in terms of the resultant Bit Error Rate (BER) versus the Signal to Noise Ratio (SNR). In order to design the power line communications channel, Middleton's class A noise model is used to account for the system's background and impulsive noise, while Zimmermann's channel model is also used. The OFDM transmission technique is taken into account. Results are derived via computer simulations.

关键词： Power Line Communications (PLC) Low Density Parity Check (LDPC) codes decoding algorithms

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Explicit measurements with almost optimal thresholds for compressed sensing

Explicit measurements with almost optimal thresholds for com...

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33rd IEEE International Conference on Acoustics, Speech and Signal Processing

作者： Parvaresh, Farzad Hassibi, Babak CALTECH Ctr Math Informat 1200 E Calif Pasadena CA 91125 USA CALTECH Dept Elect Engn Pasadena CA 91125 USA

ISBN: (纸本)9781424414833

We consider the deterministic construction of a measurement matrix and a recovery method for signals that are block sparse. A signal that has dimension N = nd, which consists of n blocks of size d, is called (s, d)-block sparse if only s blocks out of n are nonzero. We construct an explicit linear mapping Phi that maps the (s, d)-block sparse signal to a measurement vector of dimension M, where s . d < N (1 - (1 -M/N) (d/d+1)) - o(1). We show that if the (s, d)-N block sparse signal is chosen uniformly at random then the signal can almost surely be reconstructed from the measurement vector in O(N-3) computations.

关键词： convex optimization sparse signals Reed-Solomon codes decoding algorithms compressed sensing

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Security Radio Data Transmission Mode based on Turbo Codes for the CBTC System

Security Radio Data Transmission Mode based on Turbo Codes f...

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7th World Congress on Intelligent Control and Automation

作者： An, Jing Yang, Dongsheng Kang, Qi Wang, Lei Wu, Qidi Shanghai Inst Technol Shanghai 200235 Peoples R China Tongji Univ Shanghai 200092 Peoples R China Shanghai Municipal Informatizat Commiss Shanghai 200040 Peoples R China

ISBN: (纸本)9781424421138

This paper proposes a kind of security radio data transmission mode based on Turbo codes for Communication Based Train Control (CBTC) system in urban mass transit, and presents the simulation and analysis with several different decoding algorithms in this paper, such as Bi-SOVA, SOVA, MAP and Max-Log-MAP. The results show that Bi-SOVA algorithm and Max-Log-MAP algorithm have better performance of bit error. Therefore, it is reasonable and effective to use Turbo codes for replacing traditional CRC for error-correction in security radio data transmission of CBTC system.

关键词： CBTC Turbo codes decoding algorithms Error-correction Simulation and analysis

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Security Radio Data Transmission Mode based on Turbo Codes for the CBTC System

Security Radio Data Transmission Mode based on Turbo Codes f...

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7th World Congress on Intelligent Control and Automation (WCICA 2008), vol.17

作者： Jing An Dongsheng Yang Qi Kang Lei Wang Qidi Wu Shanghai Institute of Technology Shanghai China University of Tongji Shanghai China

关键词： CBTC Turbo codes decoding algorithms Error-correction Simulation and analysis

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Joint carrier phase estimation and turbo decoding using bit carrier phase APP decoder

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IEEE TRANSACTIONS ON COMMUNICATIONS 2007年第10期55卷 1884-1894页

作者： Saroka, Amir Raphaeli, Dan Hebrew Univ Jerusalem Fac Comp Sci IL-91905 Jerusalem Israel Tel Aviv Univ Fac Engn Sch Elect Engn IL-69978 Tel Aviv Israel

In this paper, we present an algorithm for joint carrier phase estimation and turbo decoding for the case of rapidly varying carrier phase during the transmitted block. The proposed algorithm shows improved performance over previously proposed communication schemes, both coherent and noncoherent, for channels with additive white Gaussian noise and high carrier phase noise. The novel algorithm utilizes a modified. "two dimensional" bit carrier phase a posteriori probability (BCAPP) decoder containing additional states representing the received carrier phase. The BCAPP decoder calculates two extrinsic metrics: one representing the bit soft value and the other representing the received carrier phase probability density function approximation. A modified structure of the turbo code iterations is suggested, implementing separate propagation of the two metrics;between the BCAPP decoders. One additional attractive property of the suggested algorithm is its robustness against phase noise model mismatch.

关键词： decoding algorithms error correction codes non-coherent reception phase decoding

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