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Hybrid firefly-Linde-Buzo-Gray algorithm for channel-optimized vector quantization codebook design

INTEGRATED COMPUTER-AIDED ENGINEERING 2017年第3期24卷 297-314页

作者： Ferreira, Felipe A. B. S. Leitao, Herbert A. S. Lopes, Waslon T. A. Madeiro, Francisco Univ Pernambuco Polytech Sch Pernambuco Recife PE Brazil Univ Fed Pernambuco Dept Elect Engn Recife PE Brazil Univ Fed Paraiba Dept Elect Engn Joao Pessoa Paraiba Brazil

This paper introduces a hybrid method that uses Firefly Algorithm (FA) and Linde-Buzo-Gray (LBG) algorithm to channel-optimized vector quantization (COVQ) codebook design. Fast nearest neighbor search (NNS) techniques are used with the purpose of execution time savings of the proposed COVQ codebook design. Simulation results concerning image transmission over a binary symmetric channel (BSC) reveal the superiority of the proposed swarm intelligence technique, referred to as FA-COVQ, over conventional COVQ codebook design method. Simulation results also reveal that the adoption of acceleration techniques in FA-COVQ codebook design can lead to execution time savings up to about 97% when compared to the FA-COVQ with brute force approach.

关键词： Image compression vector quantization channel-optimized vector quantization swarm clustering algorithm Firefly Algorithm

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PSO Algorithm Applied to Codebook Design for channel-optimized vector quantization

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IEEE LATIN AMERICA TRANSACTIONS 2015年第4期13卷 961-967页

作者： Leitao, H. A. S. Lopes, W. T. A. Madeiro, F. Univ Fed Pernambuco Recife PE Brazil Univ Fed Campina Grande Campina Grande Paraiba Brazil Univ Pernambuco Recife PE Brazil

vector quantization (VQ) has been used in signal compression systems. However, in the scenario of image transmission, VQ is very sensitive to channel errors. An approach to decrease such sensitivity is channel-optimized vector quantization (COVQ), which involves VQ codebook design taking into account the characteristics of the channel. In the present work, particle swarm optimization (PSO) is applied to codebook design for COVQ. Simulation results are presented for a variety of bit error rates of a binary symmetric channel (BSC) and reveal the effectiveness of the method in decreasing visual impairment by blocking artifacts in the reconstructed images, overperforming conventional COVQ codebook design in terms of peak signal to noise ratio of the reconstructed images for approximately 90% of exhaustive evaluations of image transmission over BSC.

关键词： image vector quantization channel-optimized vector quantization particle swarm optimization signal processing

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A Fish School Search Based Algorithm For Image channel-optimized vector quantization

A Fish School Search Based Algorithm For Image Channel-Optim...

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IEEE International Conference on Systems, Man, and Cybernetics (SMC)

作者： Ferreira, Felipe A. B. S. Madeiro, F. Univ Pernambuco UPE Recife PE Brazil

ISBN: (纸本)9781509018970

channel-optimized vector quantization (COVQ) is an alternative to vector quantization (VQ) in the scenario of transmission over noisy channels. The codebook design is an optimization problem in which a set of vectors must be optimized to represent the signals to be quantized. This paper presents a new approach to COVQ codebook design, which is a challenging optimization problem. The proposed technique embeds the Fish School Search (FSS) as a Swarm Clustering Algorithm to COVQ. Simulation results concerning a Binary Symmetric channel (BSC) reveal the superiority of the proposed technique over conventional COVQ codebook design in terms of the quality of reconstructed images.

关键词： image compression fish school search swarm clustering algorithm channel-optimized vector quantization

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A Fish School Search Based Algorithm For Image channel-optimized vector quantization

A Fish School Search Based Algorithm For Image Channel-Optim...

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IEEE International Conference on Systems, Man, and Cybernetics

作者： Felipe A. B. S. Ferreira F. Madeiro University of Pernambuco (UPE) Recife Brazil

ISBN: (纸本)9781509018987

关键词： channel-optimized vector quantization image compression fish school search swarm clustering algorithm

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On finite-state vector quantization for noisy channels

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IEEE TRANSACTIONS ON COMMUNICATIONS 2004年第12期52卷 2125-2133页

作者： Yahampath, P Pawlak, M Univ Manitoba Dept Elect & Comp Engn Winnipeg MB R3T 5V6 Canada

Finite-state vector quantization (FSVQ) over a noisy channel is studied. A major drawback of a finite-state decoder is its inability to track the encoder in the presence of channel noise. In order to overcome this problem, we propose a nontracking decoder which directly estimates the code vectors used by a finite-state encoder. The design of channel-matched finite-state vector quantizers for noisy channels, using an iterative scheme resembling the generalized Lloyd algorithm, is also investigated. Simulation results based on encoding a Gauss-Markov source over a memoryless Gaussian channel show that the proposed decoder exhibits graceful degradation of performance with increasing channel noise, as compared with a finite-state decoder. Also, the channel-matched finite-state vector quantizers are shown to outperform channel-optimized vector quantizers having the same vector dimension and rate. However, the nontracking decoder used in the channel-matched finite-state quantizer has a higher computational complexity, compared with a channel-optimized vector-quantizer decoder. Thus, if they are allowed to have the same overall complexity (encoding and decoding), the channel-optimized vector quantizer can use a longer encoding delay and achieve similar or better performance. Finally, an example of using the channel-matched finite-state quantizer as a backward-adaptive quantizer for nonstationary signals is also presented.

关键词： channel-optimized vector quantization finite-state vector quantization (FSVQ) joint source-channel coding noisy channels optimal estimation

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channel-optimized quantization with soft-decision demodulation for space-time orthogonal block-coded channels

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 2006年第10期54卷 3935-3946页

作者： Behnamfar, Firouz Alajaji, Fady Linder, Tamas Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada Hungarian Acad Sci Comp & Animat Res Inst H-1111 Budapest Hungary

We introduce three soft-decision demodulation channel-optimized vector quantizers;(COVQs) to transmit analog sources over space-time orthogonal block (STOB)-coded flat Rayleigh fading channels with binary phase-shift keying (BPSK) modulation. One main objective is to judiciously utilize the soft information of the STOB-coded channel in the design of the vector quantizers while keeping a low system complexity. To meet this objective, we introduce a simple space-time decoding structure that consists of a space-time soft detector, followed by a linear combiner and a scalar uniform. quantizer with resolution q. The concatenation of the space-time encoder/modulator, fading channel, and space-time receiver can be described by a binary-input, 2(q)-output discrete memoryless channel (DMC). The scalar uniform quantizer is chosen so that the capacity of the equivalent DMC is maximized to fully exploit and capture the system's soft information by the DMC. We next determine the statistics of the DMC in closed form and use them to design three COVQ schemes with various degrees of knowledge of the channel noise power and fading coefficients at the transmitter and/or receiver. The performance of each quantization scheme is evaluated for memoryless Gaussian and Gauss-Markov sources and various STOB codes, and the benefits of each scheme is illustrated as a function of the antenna-diversity and soft-decision resolution q. Comparisons to traditional coding schemes, which perform separate source and channel coding operations, are also provided.

关键词： channel-optimized vector quantization convolutional codes diversity joint source-channel coding multiantenna fading channels soft-decision demodulation space-time coding wireless communications

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Memory efficient adaptation of vector quantizers to time-varying channels

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SIGNAL PROCESSING 2003年第7期83卷 1519-1528页

作者： Görtz, N Kliewer, J Tech Univ Munich Inst Commun Engn LNT D-80290 Munich Germany Univ Kiel Inst Circuits & Syst Theory D-24143 Kiel Germany

channel-optimized vector quantization (COVQ) is approximated by the novel channel-adaptive scaled vector quantization (CASVQ). This new method uses a reference codebook that is optimal for one specific channel condition. However, for a bit-error rate being different from the design assumption for the reference codebook, all codevectors are scaled by a common factor, which depends on the channel condition. It is shown by simulations that a performance close to that of COVQ can be achieved in many practically important situations. Without a significant increase in complexity, the new CASVQ-scheme can be adapted to time-varying channels by adjusting the scaling factor to the current bit-error probability. Another advantage is that only one codebook needs to be stored for all error probabilities, while for COVQ either the performance degrades significantly due to channel mismatch, or a large set of codebooks, must be available at the encoder and the decoder. (C) 2003 Elsevier Science B.V. All rights reserved.

关键词： joint source-channel coding channel-optimized vector quantization time-varying channels complexity and memory requirements

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Soft-decision COVQ for turbo-coded AWGN and Rayleigh fading channels

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IEEE COMMUNICATIONS LETTERS 2001年第6期5卷 257-259页

作者： Zhu, GC Alajaji, FI Queens Univ Dept Math & Stat Kingston ON K7L 3N6 Canada Queens Univ Dept Elect & Comp Engn Kingston ON K7L 3N6 Canada

A robust soft-decision channel-optimized vector quantization (COVQ) scheme for Turbo-coded additive white Gaussian noise (AWGN) and Rayleigh fading channels is proposed. The log likelihood ratio (LLR) generated by the Turbo decoder is exploited via the use of a q-bit scaler soft-decision demodulator, The concatenation of the Turbo encoder, modulator, AWGN channel or Rayleigh fading channel, Turbo decoder, and q-bit soft-decision demodulator is modeled as an expanded discrete memoryless channel (DMC), A COVQ scheme for this expanded discrete channel is designed. Numerical results indicate substantial performance improvements over traditional tandem coding systems, COVQ schemes designed for hard-decision demodulated Turbo-coded channels(q = 1), as well as performance gains over a recent soft decoding COVQ scheme by Ho.

关键词： AWGN channels channel-optimized vector quantization joint source-channel coding Rayleigh fading channels soft-decision demodulator turbo codes

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