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International Conference on Communication Systems

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

The author 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. Minimax redundancy is defined as the maximum difference between the expected per-symbol code length and the per-symbol source entropy in the source range. A universal coding scheme is formulated in terms of the weight function, i.e., a method is presented for determining a weight function which minimizes the minimax redundancy even when the true model is unknown. It is subsequently shown that the minimax redundancy achieved through the presented coding method is upper-bounded by the minimax redundancy of J. Rissanen's semi-predictive coding method.< >

关键词： Minimax techniques Stochastic processes Entropy Educational institutions Probability distribution Arithmetic H infinity control adaptive coding

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PRACTICAL DICTIONARY MANAGEMENT FOR HARDWARE DATA-COMPRESSION

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COMMUNICATIONS OF THE ACM 1992年第1期35卷 95-104页

作者： BUNTON, S BORRIELLO, G Univ. of Washington Seattle Univ. of Washington Seattle

This article addresses the problem of realizing the second textual substitution compressor in hardware and evaluate the combined effects of dictionary size and of various dictionary management mechanisms on the performance of a Ziv-Lempel encoder, and then present a new dictionary manager which resolves the time-space trade-offs of its predecessors. The second data compression scheme repeatedly matches the input stream to words contained in a dictionary, and returns pointers to locations in the dictionary of the longest matches. Dictionary management scheme employs a trie data structure with uniquely fit tagged nodes whose tags satisfy a modified heap property. Dictionary access is done by using hashing technique and associative memory approaches. Performance of deletion heuristics, Ziv-Lempel compression on binary files is done FREEZE, FLUSH, SWAP are tested and the compression ratio is also plotted. This tagged decompressor architecture consists of three coupled parallel processes.

关键词： ALGORITHMS DESIGN EXPERIMENTATION THEORY adaptive coding CONTENT-ADDRESSABLE MEMORY FILE COMPRESSION SPECIAL-PURPOSE HARDWARE TEXTUAL SUBSTITUTION ZIV-LEMPEL ENcoding

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Synthesis from production-based specifications

Synthesis from production-based specifications

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Design Automation Conference

作者： A. Seawright F. Brewer Department of Electrical and Computer Engineering University of California Santa Barbara CA USA

The authors describe a model for, and an implementation of, production-based synthesis of hardware description language (HDL) code in which the overall structure of the resultant machine is derived from a hierarchy of sub-machine descriptions, each represented by a production. The production-based specification (PBS) consists of productions annotated with HDL action code, and forms the input to a design tool which outputs procedural HDL tailored for hardware synthesis. Due to the concise nature of this form of specification, the technique can save enormous labor in the construction of procedural specifications for these machines. Novel aspects of this research include the compilation of a PBS with HDL action clauses into synthesizable procedural HDL and the approach to specification of machine behavior in the event of exceptional conditions.< >

关键词： Hardware design languages Production Protocols Communication system control Software tools adaptive coding Design automation Software design

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Efficient adaptive cooling rate hybrid ARQ protocols

Efficient adaptive cooling rate hybrid ARQ protocols

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IEEE International Conference on Communications (ICC)

作者： S. Kallel Department of Electrical Engineering University of British Columbia Vancouver BC Canada

Efficient stop-and-wait, go-back-N and selective-repeat hybrid automatic-repeat-request (ARQ) protocols with adaptive forward error correction using punctured and repetition convolutional coding are proposed and analyzed. The basic idea is to vary the coding rate for error correction according to system parameters, such as the signal-to-noise ratio, the round trip delay and the buffer size at the receiver, so as to maximize the throughput efficiency. The authors refer to these schemes as adaptive coding rate (ACR) ARQ protocols. The performance of the proposed ACR ARQ protocols is evaluated for an additive white Gaussian noise channel.< >

关键词： adaptive coding Automatic repeat request Protocols Forward error correction Convolutional codes Convolution Error correction codes Signal to noise ratio Delay Throughput

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A robust rate-adaptive hybrid ARQ scheme and frequency hopping for multiple-access communication systems

A robust rate-adaptive hybrid ARQ scheme and frequency hoppi...

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[Conference Record] GLOBECOM '92 - Communications for Global Users: IEEE

作者： A.M.Y. Bigloo Q. Wang V.K. Bhargava Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

A frequency-hopped spread-spectrum multiple-access (FH-SSMA) communication system with a rate-adaptive coding scheme is considered. The scheme uses a variable-rate Reed-Solomon code, with a single decoder. Two cases are considered: N-ary frequency-shift keying (FSK) without erasure and N-ary FSK with perfect side information as to whether a channel symbol is hit or not. It is shown that FH-SSMA with this rate-adaptive coding scheme can serve a higher number of users than with fixed-rate coding for the above mentioned cases. This increase in the number of users is due to the higher throughput which results in less interference for the other users. It is shown that perfect side information increases the capacity of the system. The number of users can further increase if more time delay is allowed in the system.< >

关键词： Robustness Automatic repeat request Spread spectrum communication Frequency shift keying Decoding Interference Forward error correction Throughput Reed-Solomon codes adaptive coding

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adaptive coding and optimal speech storage in digital speech interpolation systems

Adaptive coding and optimal speech storage in digital speech...

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ACE. Proceedings of [Annual Convention and Exhibition of the IEEE In India]

作者： P.S. Tiwari K.C. Harit Department of Elecronics and Communication Engineering University of Jodhpur Jodhpur India

One of the important issue in speech interpolation is that of speech freeze-out which becomes a very serious consideration with multihop networks. The paper discusses the implementation of two such techniques namely speech storage and variable bitrate strategies with their independent and combined effects on the performance of multihop, DSI networks. The trade-off between the effective increased channel capacity and the degradation of the speech quality has also been pointed out. The basic architectural configuration of the system using multimicroprocessor system has been discussed and the potentialities of the method in accomodating newer versions of coding algorithms at desired speed of response have been included.

关键词： Speech coding adaptive coding Interpolation Detectors Channel capacity Degradation Intelligent networks Spread spectrum communication Telephony Speech processing

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Design of an adaptive coding and retransmission strategy for a multipath fading channel

Design of an adaptive coding and retransmission strategy for...

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IEEE Conference on Vehicular Technology (VTC)

作者： S. Le-Ngoc Faculty of Engineering and Applied Science Memorial University of Newfoundland Saint John's NEW Canada

A high performance data communication system is designed using a 2.5 GHz radio with a data transmission rate of 6.312 Mbit/s and a 800 MHz radio with a data transmission rate of 4800 bit/s. To countermeasure both random bit and burst errors, Reed-Solomon (RS) codes are considered for the forward and reverse channels. The system reliability is improved by using an adaptive forward error correction (FEC) scheme in the forward channel and a conventional FEC scheme in the reverse channel. As a result, the stop-and-wait protocol is used to simplify the circuitry and avoid large buffers, and yet the system requirement can still be met. The proposed coding and retransmission strategy seems suitable for use in a severe multipath fading.< >

关键词： adaptive coding Fading Bit error rate Forward error correction Directive antennas Receiving antennas Data communication Automatic repeat request Remotely operated vehicles Transmitting antennas

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Variable resolution-adaptive sampling approach to image coding

Variable resolution-adaptive sampling approach to image codi...

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IEEE Southeastcon

作者： S. Liu M. Hayes School of Electrical Engineering Georgia Institute of Technology Atlanta GA USA

Since the local characteristics of an image usually change from region to region, adaptive coding techniques are necessary to achieve high compression rates. An effective coding scheme is based on the principle of variable resolution image representation, where compression is generally achieved by adaptive sampling or subsampling. Various adaptive sampling schemes that are effective for image compression are developed and evaluated. The main focus is the design of the nonuniform sampling patterns associated with the sample selection process. Two different design procedures, based on nonrecursive and recursive image decomposition, are investigated. Simulation results indicate that some of the sampling schemes proposed here attain higher compression rates than other reported coders of this nature.< >

关键词： Image resolution Image sampling Image coding Nonuniform sampling Digital images Image reconstruction Bandwidth Degradation adaptive coding Focusing

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General purpose data compression ICs

General purpose data compression ICs

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IEEE Compcon

作者： D.R. Helman Computer Engineering University of California Santa Cruz USA

Three commercially available data compression ASICs are compared: the Hewlett-Packard MYSTIC, the Infochip IC-1053, and the Stac 9703. All three are suitable for lossless compression of general data including text, object code, databases, etc. All use a form of Ziv-Lempel adaptive coding and can be integrated into a standard microprocessor system. Compression performances are compared and found to be similar, in the general vicinity of 2 to 1.< >

关键词： Data compression Dictionaries Image coding Data engineering Databases adaptive coding Microprocessors Computer industry Microcomputers Hardware

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The Worst-case Performance Of adaptive Huffman Codes

The Worst-case Performance Of Adaptive Huffman Codes

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IEEE International Symposium on Information Theory

作者： J.A. Storer Computer Science Department Brandeis University Waltham MA USA

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