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IEEE 72nd Vehicular Technology Conference Fall 2010

作者： Shehata, Tarik S. Marsland, Ian El-Tanany, Mohamed Carleton Univ Dept Syst & Comp Engn Ottawa ON K1S 5B6 Canada

ISBN: (纸本)9781424435746

The design of Viterbi decoders for signals in noise modeled using the symmetric alpha-stable distribution is considered. The traditional Viterbi decoder, which has a branch metric optimized for Gaussian noise, performs poorly in symmetric alpha-stable noise. Since the optimal maximum likelihood branch metric is impractically complex, many suboptimal metrics have been proposed, such as the hard decision, p-norm and absolute (1-norm) metric. A Viterbi decoder that uses the absolute branch metric has better performance and lower complexity, however, its performance degrades when alpha decreases. In this paper, the effects of the suboptimal metrics on the performance of the Viterbi decoder are analyzed, and a clear justification for the performance of the decoder that uses the Gaussian and absolute metrics is provided. Moreover, this analysis is used to design a low complexity suboptimal branch metric that improves the performance of the Viterbi decoder by about 0.75 to 2 dB compared to the absolute branch metric for different values of alpha, at almost no additional complexity.

关键词： Viterbi decoders Metronidazole convolutional coding Metric branches Noise CENTROSYMMETRIC

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Remote accessible laboratory for error controlled coding techniques with the labview software

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Procedia - Social and Behavioral Sciences 2010年第2期2卷 372-377页

作者： Berkay Erder Aynur Akar Technical Education Faculty Marmara University İstanbul 34180 Turkey

Whilst the laboratory works at faculties providing education on the field of electronics and communication support the technical knowledge of students, they also develop their implementation abilities. The fact that there is less equipment requiring advanced technologies in laboratories, enforces the students to group works and thus limits working time and their contribution to the experiments. Contemporary computer technology provides the possibility for establishing alternative laboratories, environments in which the students can perform implementations without the restrictions of location and time. In this work, real time remote accessible experiment sets are prepared regarding coding techniques with error control. It is provided that the students can connect to the web based laboratory system via any computer on the LAN and make experiments. In this laboratory, the student will perform real time implementations without the restriction of location and time and strengthen their theoretical knowledge.

关键词： LabVIEW Error Control coding Remote Accessible Laboratory WEB Based Learning Block coding convolutional coding Turbo coding

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Decoding Real Numbered Block and convolutional Codes with Erasure and Impulsive Noise Channels

Decoding Real Numbered Block and Convolutional Codes with Er...

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European Signal Processing Conference

作者： S. Jafarzadeh M. Khatami F. Marvasti Department of Micro and Nanotechnology Technical University of Denmark Lyngby Denmark Sound Technology Inc Analogic Ultrasound Group USA

In this paper, a class of real numbered block and convolutional codes are encoded and decoded using various iterative methods to remove channel impulsive noise and erasures. In order to recover the received vector, two iterative algorithms are used for erasure and impulsive noise distortions. Similarities of real number convolutional codes to linear block codes are discussed. An iterative method with adaptive thresholding is described for the reconstruction of impulsive noise using sparse signal processing.

关键词： Real number codes Impulsive noise cancellation Erasure channel convolutional codes Iterative technique IMAT method convolutional coding Impulse noise erasure channel iterative methods linear block code Real number adaptive thresholding

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Detection and Performance of Coded FSK Wireless Telemeter Signals

Detection and Performance of Coded FSK Wireless Telemeter Si...

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1st International Conference on Networking and Digital Society

作者： Liu, Wei Zhang, Chun-yang Xiang, Fei Henan Univ Sci & Technol Sch Elect Informat Engn Luoyang 471003 Henan Peoples R China

ISBN: (纸本)9780769536354

The noncoherent symbol-by-symbol maximum a posteriori (MAP) detection and the soft-decision Viterbi decoding in a convolutionally coded frequency shift-keying (FSK) telemeter system are studied and the performance of coded FSK telemeter system in flat Rayleigh-fading channel is also analyzed. The coded bit metrics of FSK signal are calculated by MAP detector, and the bit metrics are applied in realization of soft-decision Viterbi decoding. The results show that the reliability of FSK telemeter system can be improved by MAP detection and soft-decision Viterbi decoding. Compared with the envelop detection and hard-decoding of coded FSK signal over flat Rayleigh -fading channel, the potential gain of 6-8dB can be obtained by using MAP detection and soft-decision Viterbi detection.

关键词： wireless telemetry frequency shift keying convolutional coding maximum a posteriori detection Viterbi decoding

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Optimized decision-feedback equalization for convolutional coding with reduced delay

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IEEE TRANSACTIONS ON COMMUNICATIONS 2005年第11期53卷 1859-1866页

作者： Liu, JT Gelfand, SB Spreadtrum Commun Inc Saratoga CA 95070 USA Purdue Univ Sch Elect & Comp Engn W Lafayette IN 47907 USA

Error propagation is a significant problem with the decision-feedback equalizer (DFE) at low-to-moderate signal-to-noise ratios. In particular, when a DFE is concatenated with a convolutional code, the burst errors associated with error propagation can severely degrade performance, since the convolutional code is optimized for the additive white Gaussian noise channel. In this paper, we explore the compensation of error propagation in the DFE so as to break up error bursts and improve performance with convolutional codes, without incurring larger overall decoding delay. We propose certain stationary error models and derive a modified DFE (MDFE) based on these models which can compensate for the error propagation. The MDFE differs from the conventional DFE only in its tap values. The incorporation of the bias into the model and the removal of the bias during the design process is discussed. Simulations explore the performance of the MDFE for both uncoded and convolutionally coded systems. With coding, the MDFE can significantly improve on the conventional DFE in terms of bit-error rate, and the MDFE without interleaving can improve on the conventional DFE with interleaving in terms of decision delay.

关键词： convolutional coding decision-feedback equalization error propagation union bound

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Pre-processing of convolutional codes for reducing decoding power consumption

Pre-processing of convolutional codes for reducing decoding ...

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

作者： Shao, Wei Brackenbury, Linda Univ Manchester APT Grp Sch Comp Sci Manchester M13 9PL Lancs England

ISBN: (纸本)9781424414833

This paper presents a new pre-processing approach for convolutional codes that can provide the adaptive capability to a standard Viterbi decoder. By identifying and generating the decoded data from the zero Hamming distance path, all computations in the Viterbi decoder can be avoided. This makes it possible to stop the Viterbi decoder in real time as long as no error occurs in the received code words;the Viterbi decoder is restarted to correct errors otherwise. With this approach, significant power, i.e. 97% of a standard Viterbi decoder power dissipation, can be saved when the Eb/No is as low as 13dB.

关键词： convolutional coding adaptive decoding algorithm pre-decoding

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A multiple copyright identification watermarking algorithm based on code division multiple access

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High Technology Letters 2008年第4期14卷 377-383页

作者：张帆 li Jie Su Yuting Zhang Chuntian College of-Computer ＆ Information Engineering Henan University Kaifeng 475001 P. R. China College of Electronic ＆ Information Engineering Tianjin University Tianjin 300072 P.R. China

A multiple watermarking algorithm is presented according to the multiple accessing technique of the code division multiple access （CDMA） system. Multiple watermarks are embedded into digital images in the wavelet transform domain. Each of the watermarks is embedded and extracted independently without impacts to each other. Multiple watermarks are convolution encoded and block interleaved, and the orthogonal Gold sequences are used to spread spectrum of the copyright messages. CDMA encoded water-mark messages are embedded into the wavelet sub-bands excluding the wavelet HH1 sub-bands. The embedment amplitude is decided by Watson＇ s perceptual model of wavelet transform domain, and the embedmeut position in the selected wavelet sub-bands is decided randomly by a pseudo-random noise （PN） sequence. As a blind watermm＇king algorithm, watermarks are extracted without original image. The watermarking capacity of proposed algorithm is also discussed. When two watermarks are embedded in an image at the same time, the capacity is larger than the capacity when a single watermark is embedded, and is smaller than the sum of the capacity of two separately embedded watermarks. Experimental results show that the proposed algorithm improves the detection bits error rate （BER） observably, and the multiple watermarks have a preferable robustness and invisibility.

关键词： code division multiple access （CDMA） watermarking convolutional coding

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Forward Error Correction Techniques Suitable for the Utilization in the PLC Technology

Forward Error Correction Techniques Suitable for the Utiliza...

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International Conference on Systems, Signals and Image Processing

作者： Stanislav Dlhan Department of Telecommunications FEI STU Bratislava Ilkovicova 3 812 19 Bratislava Slovakia

ISBN: (纸本)9788022728560

Today's PLC systems are mostly limited in transmission speeds to several kilobits per seconds. Such speeds are certainly not sufficient for running popular services like a broadband Internet, a teleworking or the Video on Demand. This fact is reducing a chance of the PLC technology's deployment in a wide range. One way how to overcome this problem could be in introduction of optimal errors correcting techniques into the PLC technology. In this contribution, different types of coding techniques are discussed, including RS, Turbo or convolutional codes. Theoretical analyses are focused on their positive and negative features visible in case of their deployment in the PLC transmission environment. Special attention is pointed to their robustness against noises, which is analyzed also practically in form of the simulations. Analyses and simulations are done for individual codes as well as combination of codes.

关键词： The PLC environment The PLC transmission channel The PLC simulation model RS Turbo code convolutional code convolutional coding turbo codes Programmable logic controllers deployment Forward error correction Noise

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Turbo modulation and coding: Design and evaluation of iterative bit-interleaved coded modulation methods for wireless systems beyond 3G

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EUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS 2007年第8期18卷 845-850页

作者： Bauch, Gerhard Schreckenbach, Frank Hausl, Christoph Abel, Tetsushi DoCoMo Euro Labs D-80687 Munich Germany Tech Univ Munich Inst Commun Engn D-80290 Munich Germany

We give an overview of iterative techniques for bit-interleaved coded modulation. We start with simple methods where a convolutional code is concatenated with a standard QAM modulation scheme. The mapping is carefully chosen different from Gray mapping such that significant gains can be obtained by an iterative (turbo) receiver. The idea can also be applied to transmit antenna diversity as well as spatial multiplexing (MIMO). We then consider various powerful iterative coding schemes which are under discussion in standardisation for wireless systems beyond 3G such as serial or parallel concatenated convolutional codes, repeat accumulate codes and LDPC codes. We give a comparison in terms of complexity and performance. The main intention is to provide an illustrative overview over relevant applications of the turbo principle in demodulation and decoding. It is a summary of results which have been obtained in collaboration between the Institute of Communications Engineering, TUM and DoCoMo Euro-Labs. Copyright (C) 2007 John Wiley & Sons, Ltd.

关键词： third generation Turbo coding Bit interleaved coded modulation Worm gears Iterative modulation mode low density parity check codes CARRIER SYSTEM convolutional coding Demodulation

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A NEW EFFICIENT convolutional DECODER FOR GSM COMMUNICATION STANDARD WITH FUZZY LOGIC

A NEW EFFICIENT CONVOLUTIONAL DECODER FOR GSM COMMUNICATION ...

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4th Advanced International Conference on Telecommunications (AICT 2008)

作者： S. Ananthi K. Visalakshi S. Rajakumari University of Madras Chennai India Womens Polytechnic College India

In GSM communication, one of the aspects is the convolutional encoding of speech data, using a 16 state encoder. Since for every bit, additional v bits are transmitted, there is good scope for error detection and correction. Using state diagram at each time slot, Trellis diagrams are considered as good illustrations for the method of decoding the data and an algorithm by Viterbi is in vogue. Compared to that, the proposed technique is based on the assignment of probability values to the states at all bit timings using certain principles of fuzzy logic. By this, the length limitation of the earlier algorithm is overcome since the memory requirement is only to store the best probable fuzziness values at each time slot and hence faster and code efficient. Comparative illustrations for sample data are given. Further, the method yields the same result of the best possible data accuracy as with the trellis coding. The method has been exhaustively tested for its reliable decoding.

关键词： convolutional coding Trellis decoder Viterbi's algorithm GSM speech encoding Fuzzy logic

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