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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Zhenga He Jihong Zhang Yiming Mao Radio Engineering Department South-East University Nanjing China

The authors developed a new adaptive image coding technique using interpolative mixed vector quantization (VQ) which mixes the 2D discrete cosine transform (DCT) with VQ. A median filter is first used to eliminate fine noise while not smearing the edges. After subsampling, the image is encoded by an adaptive mixed VQ coding scheme. At the receiver, a finite-impulse-response (FIR) median hybrid filter is used to interpolate missing pixels after subsampling. Some simulation results are given. It was found that high-quality coded images were obtained at a bit rate from about 0.25 to 0.5 b.p.p.< >

关键词： Image coding Bit rate Discrete cosine transforms Finite impulse response filter Filtering Helium Vector quantization adaptive filters adaptive coding Image analysis

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Efficient coding of LPC parameters using adaptive prefiltering and MSVQ with partially adaptive codebook

Efficient coding of LPC parameters using adaptive prefilteri...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Y. Tanaka T. Taniguchi Fujitsu Laboratories Limited Kawasaki Japan

The authors propose an efficient vector quantization scheme and a novel linear predictive coding (LPC) analysis scheme, both of which exploit interframe correlation in the successive spectrum envelope of speech signals. The first quantization scheme proposed is a multistage vector quantization of line spectrum pair (LSP) parameters with a partially adaptive codebook (MSVQ-AC). The second algorithm is an LPC analysis scheme, with closed-loop adaptive prefiltering (LPC-PF), which realized temporary higher-order analysis than the standard LPC with a few additional transmission bits. A combined system of the LPC-PF and two-split, two-stage VQ with the adaptive codebook can quantize tenth-order LSP parameters at around 23 bits/frame, realizing sufficient quality and reasonable complexity.< >

关键词： Linear predictive coding adaptive coding Vector quantization Encoding Delay Speech analysis Bit rate Speech coding Discrete cosine transforms Laboratories

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AN APPLICATION OF THE HOPFIELD MODEL TO HUFFMAN CODES

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IEEE TRANSACTIONS ON INFORMATION THEORY 1993年第3期39卷 1071-1076页

作者： FABRIS, F DELLARICCIA, G Dipartimento di Matematica e Informatica Universita degli Studi di Udine Udine Italy

The discrete neural network model due to Hopfield (1982), and his following developments, allow to tie the dynamical evolution of a neural network to a quantity-the energy of the network-which is monotonically decreasing up to a minimum stable point. A network of this kind is able to ''solve'' efficiently some useful computational problems. An application of the neural Hopfield model to the source (optimal) coding problem is shown;this application gives the structure of a Hopfield network, which is able to calculate the lengths of the codewords that must be associated to a source alphabet so as to minimize their average length. The case of a stationary and memoryless block-to-variable-length (B-VL) source coding is discussed.

关键词： SOURCE coding HUFFMAN CODES adaptive coding NEURAL NETWORKS PARALLEL COMPUTATION

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AN adaptive coding SCHEME FOR TIME-VARYING CHANNELS

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IEEE TRANSACTIONS ON COMMUNICATIONS 1991年第5期39卷 653-663页

作者： VUCETIC, B UNIV SYDNEY SCH ELECT ENGNSYDNEYNSW 2006AUSTRALIA

This paper presents an adaptive coding scheme for digital communication over time-varying channels. The scheme is based on a finite-state Markov channel model. Emphasis is on the adaptation of the error protection to the actual channel state. The throughput gains that are achieved by the adaptive scheme relative to the conventional nonadaptive coding methods are demonstrated by several examples. Of special interest is the use of punctured convolutional codes with maximum-likelihood Viterbi algorithm to enable adaptive encoding and decoding without modifying the basic structure of the encoder and the decoder.

关键词： adaptive coding Time-varying channels Convolutional codes Maximum likelihood decoding Error correction Error correction codes Viterbi algorithm Error probability Protection Throughput

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Practical implementation of a mobile data link protocol with a Type II hybrid ARQ scheme and code combining

Practical implementation of a mobile data link protocol with...

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IEEE Conference on Vehicular Technology (VTC)

作者： S. Bakhtiyari T. Chen S. Kallel V. Leung Department of Electrical Engineering University of British Columbia Vancouver BC Canada

The design of an efficient mobile data link protocol (MDLP) based on a Type II hybrid automatic request for repetition (ARQ) scheme using convolutional coding and code combining is presented. An adaptive coding scheme for the header is proposed and analyzed. Simulation results show significant improvement in throughput at low SNR as compared to conventional schemes. Precise specification of the MDLP using a formal description technique based on Estelle is outlined and discussed.

关键词： Protocols Automatic repeat request Decoding Convolutional codes adaptive coding Channel estimation Data communication Error correction Transmitters Throughput

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A Type I hybrid ARQ system with adaptive code rates

A Type I hybrid ARQ system with adaptive code rates

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IEEE Singapore International Conference on Networks

作者： M.L. Lin R.H. Deng Department of Electrical Engineering National University of Singapore Singapore

Type I hybrid ARQ systems use an error-control code of fixed rate for error-correction in each transmitted packet. In such systems, the code rate must be carefully chosen to match the channel bit error rate (BER) in order to maximize system throughput. Whenever there is a mismatch between code rate and channel BER, the throughput suffers. This paper proposes a type I hybrid ARQ system which automatically adjusts its code rates to match channel BERs. The proposed system is very simple to implement and yet performs significantly better than type I hybrid ARQ systems of fixed code rate.

关键词： adaptive coding Bit error rate Decoding Throughput Viterbi algorithm Automatic repeat request Convolutional codes Hamming distance Hybrid integrated circuits Protocols

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Characterization of the resonant and coupling parameters of dielectric resonators of NRD-guide filtering devices

Characterization of the resonant and coupling parameters of ...

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Microwave, MTT-S International Symposium

作者： F. Frezza A. Galli G. Gerosa P. Lampariello Department of Electronic Engineering University of Roma La Sapienza Italy

The design of millimeter-wave filtering devices using dielectric resonators of various shapes in nonradiative dielectric (NRD) waveguides is considered. By developing different approximate and rigorous theoretical methods, the resonant and coupling properties (frequencies, field configuration, unloaded and loaded quality factors, scattering parameters, etc.) are modeled and implemented in an adaptive code. Experimental comparison through suitable measurements are performed to validate the theoretical and numerical results.< >

关键词： Resonance Dielectric devices Resonator filters Filtering Millimeter wave technology Shape Frequency Q factor Scattering parameters adaptive coding

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Minimax Redundancy for Sources with an Unknown Model

Minimax Redundancy for Sources with an Unknown Model

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IEEE International Symposium on Information Theory

作者： J. Suzuki College of Science and Engineering Aoyama Gakuin University Tokyo Japan

This paper describes the construction of a universal code for minimizing L.D. Davisson's minimax redundancy in a range where the true model and stochastic parameters are unknown.

关键词： Minimax techniques Stochastic processes Educational institutions Probability distribution adaptive coding Statistics Learning systems

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adaptive CODE EXCITED PREDICTIVE coding

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IEEE TRANSACTIONS ON SIGNAL PROCESSING 1992年第6期40卷 1317-1326页

作者： GALAND, CR MENEZ, JE ROSSO, MM UNIV NICE SOPHIA ANTIPOLISFRANCE LASSY CNRSURA 1376EQUIPE 135F-06041 NICEFRANCE IBM CORP THOMAS J WATSON RES CTRDEPT COMP SCIYORKTOWN HTSNY 10598 IBM CORP DEPT ARCHITECTURE & TELECOMMUNRES TRIANGLE PKNC

Since its recent introduction by Atal and Schroeder, the code excited linear predictive (CELP) coder has been thoroughly and widely studied by the speech coding research community, and has already been adapted to several standards for telephone speech coding. The CELP algorithm represents a breakthrough in speech coding, for it encodes telephone quality speech at 8 kb/s without noticeable distortion. Previously, this performance was achievable by coders operating at 16 kb/s or higher. However, the drawback of the CELP is its inherent complexity, which, despite the fast progress of the technology, may represent a problem of cost or feasibility in products. In this paper, we discuss a new way to consider the CELP concept, which allows us to cut the processing load while keeping the same speech quality. Rather than performing the individual weighting of each candidate sequence, we propose a global implementation of the perceptual weighting function at the codebook level. As a result, the analysis-by-synthesis procedure does not require the processing of all the candidate sequences through the synthesis and weighting filters, and therefore the complexity requirement of the algorithm is much reduced. The new concept is carried out with an adaptive codebook. We report on two fixed-point implementations of our adaptive CELP (ACELP) algorithm: a 7.2 kb/s block coder (7 MIPS), and a 12 kb/s low-delay coder (11 MIPS). Both coders have been rated to provide the same quality as the 13 kb/s block coder adopted by the GSM for the European cellular telephone.

关键词： adaptive coding Predictive coding Filters Speech coding Telephony Speech analysis Technological innovation Signal processing Code standards Costs

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IMAGE-coding WITH THE DISCRETE COSINE-III TRANSFORM

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IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS 1992年第5期10卷 884-891页

作者： ERSOY, OK NOUIRA, A School of Electrical Engineering Purdue University West Lafayette IN USA

The discrete cosine-III transform (DC3T) is the same as the discrete symmetric cosine transform (DSCT) with a specific preprocessing of input data. It has less computational complexity than the discrete cosine transform (DCT) in terms of multiplications. The DC3T is also related to the DCT by a weighting matrix. The performance of the DC3T is compared to the DCT when compression is performed by adaptive coding. Experimental results show that a significant improvement in visual performance and mean square reconstruction error can be achieved over what is possible with the DCT. The better performance is attributed to the weighting of the DCT coefficients, which is indirectly achieved at reduced computational cost.

关键词： Image coding Discrete transforms Discrete cosine transforms Covariance matrix Symmetric matrices adaptive coding Karhunen-Loeve transforms Data preprocessing Computational complexity Image reconstruction

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