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IEEE International Symposium on Information Theory

作者： B. Ryabko J. Astola Siberian State University of Telecommunications and Computer Science Novosibirsk Russia Tampere International Center for Signal Processing Technical University of Tampere Finland

This paper suggests a scheme of adaptive coding and prediction for a case where a source generates letters from an alphabet with unknown (and even infinite) size. This scheme can be applied along with any predictor; here we use the Laplace predictor as the main example. We consider a case of prediction for i.i.d. sources, but all results can be easily extended to Markov sources. The suggested scheme is described using the tree notation.

关键词： adaptive coding Redundancy Statistics Computer science adaptive signal processing Application software Information theory Probability Prediction methods Data compression

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A Study of adaptive coding and Modulation Over Free Space Optical Link Using OCTL Data

A Study of Adaptive Coding and Modulation Over Free Space Op...

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IEEE Aerospace Conference

作者： Jay L. Gao Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Dr. Pasadena CA 91109

ISBN: (纸本)9781467376778

In this paper we utilized the downlink channel data captured at the Optical Communication Test Laboratory (OCTL) in support of the Lunar Laser Communications Demonstration (LLCD) to evaluate the potential performance gain of using adaptive coding and modulation (ACM) scheme to increase data volume while mitigating weather impairment. The study assumed that the estimated signal and noise photon counts statistics generated by concurrent processing of the downlink signal is available in real time to drive a closed-loop control of the code rate and the PPM order of the downlink. Downlink data from two representative passes were used. Pass no. 12, which occurred on October 29, 2013 and lasted 24 minutes and 15 second, recorded several link outages due to thin cloud and cloud interruption and is used to calibrate the symbol error constraint for the adaptive modulation algorithm. Pass no. 20, which was 19 minutes and 16 seconds long and occurred on November 18, 2013, operated over very clear sky and large sun-earth-probe (SEP) angle (approx. 170 degrees) and provided a representative sample of a clean optical channel. This study ignores constraints such as peak and average power limitations and processing overhead. Impacts of delay in the control loop are not addressed in this study, therefore any performance enhancement indicated by this study is only applicable to a short propagation delay environment. For deep space environment, further analysis will be required to determine the benefit of ACM.

关键词： OCTL LLCD ACM adaptive coding control ring downlink signal code rate Downlink PARALLEL PROCESSING (COMPUTERS) Optical links enhancing performance

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A novel adaptive coding scheme for throughput maximization over Rayleigh fading channels based on the use of Markov chains

A novel adaptive coding scheme for throughput maximization o...

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National Conference on Radio Science (NSRC)

作者： M.H. Ismail H.-A.M. Mourad Cairo University Giza EG Dept. of Electron. & Electr. Commun. Cairo Univ. Giza Egypt

adaptive coding techniques have been proposed in the literature as a method of increasing the throughput obtained by each user in wireless communication systems. Some of these schemes, along with adaptive modulation, have been adopted as part of the next generation mobile communications systems standards including GPRS and EDGE. These systems aim at providing users with high data rates reaching approximately 400 Kbps. In this paper, we present a novel adaptive coding technique for Rayleigh fading channels based on the use of Markov chains. A complete mathematical analysis of the system is presented and the performance of the system is compared, in terms of throughput, to other nonadaptive schemes pointing out its efficiency in obtaining the maximum throughput.

关键词： adaptive coding Throughput Fading Protection Wireless communication Mobile communication Mathematical analysis Radio transmitters adaptive systems Cities and towns

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DVB-S2 adaptive coding and Modulation for HAP Communication System

DVB-S2 Adaptive Coding and Modulation for HAP Communication ...

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IEEE Conference on Vehicular Technology (VTC)

作者： Miha Smolnikar Tomaz Javornik Mihael Mohorcic Matteo Berioli Department of Communication Systems Jozef Stefan Institute Ljubljana Slovenia Institute of Communications and Navigation German Aerospace Center Oberpfaffenhofen Germany

Combining some of the best terrestrial and satellite systems' characteristics, high altitude platforms (HAPs) have recently emerged as an alternative solution for the provision of broadband services. Characterised by challenging propagation conditions in the allocated frequency bands, they require efficient utilisation of radio interface in order to make best use of the available spectrum. This paper analyses possible utilisation of DVB-S2 standard on HAPs, focusing on the performance of its adaptive coding and modulation (ACM) procedures as a mean of maximizing the link reliability and throughput. Two distinct operating scenarios are addressed, one assuming static channel conditions with the applied rain fading and the other representing mobile channel conditions along a representative railway track We show that by considering only a subset of transmission modes (MODCODs) defined by the DVB-S2 standard, the system could be optimized in terms of achievable spectral efficiency as well as in terms of implementation complexity. A procedure for optimal MODCOD subset selection is proposed, taking into account the predefined switching thresholds and round-trip time delay.

关键词： Digital video broadcasting adaptive coding Modulation coding Satellite broadcasting Radio spectrum management Performance analysis Throughput Rain fading Rail transportation Delay effects

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Subjective quality evaluation of different intraframe adaptive coding schemes, based on orthogonal transformations

Subjective quality evaluation of different intraframe adapti...

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

作者： M. Guglielmo R. Marion A. Sciarappa Centro Studi e Laboratori Telecomunicazioni S.P.A. CSELT Torino Italy

This paper describes a subjective test for comparing different video intraframe coding methods based on adaptive orthogonal transformations. A set of images were objectively measured, in terms of mean square error, by means of computer simulation using a 16×16 Discrete Cosine Transform (DCT) in the following situations: - non adaptive transform coding - adaptive coding obtained through multiplicative coefficient for the quantiser level, according to the activity classes - adaptive coding with a constant mean square error per sub-block. Subjective and objective measures show a low correlation if a non adaptive coding scheme is used, while the correlation is higher if adaptive coding schemes are used. In particular, the uniform impairment distribution (the same quantisation error for each block) supplies a very high correlation between the two measures. Subjective evaluations were carried out using a SSR (Single Stimulus Rating) method; results are presented in terms of mean and standard deviation. Analysis of variance (ANOVA) was also performed to evaluate factor and interaction contribution to variability.

关键词： adaptive coding Mean square error methods Discrete cosine transforms Analysis of variance Testing Computer simulation Transform coding Quantization Particle measurements Performance evaluation

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On the inadequacy of Golomb-Rice codes for adaptive coding

On the inadequacy of Golomb-Rice codes for adaptive coding

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Data Compression Conference (DCC)

作者： A. Said Hewlett Packard Laboratories Palo Alto CA USA

Summary form only given. Complex data sources, like images and audio, require sophisticated coding contexts and source modeling. Fortunately, in many cases the high cost for estimating a very large number of conditional probabilities and then computing optimal codes, can be avoided by storing sets of codewords, and selecting the best choice based on local source estimates. Golomb-Rice prefix codes are commonly used for such purposes because of their convenient features. We consider the fact that, even when the source distribution is geometric, the Golomb-Rice codes are truly optimal only when the source parameter, /spl rho/, is known with certainty, which in practice is never the case. We investigate how these codes perform - on sources with geometric distribution - depending on how /spl rho/ is estimated from previous samples. We analyze possible changes in the code to increase robustness, but keeping the useful structural properties. The intention is not to propose a "new" type of code for particular applications, but to observe how the optimal codes change with different models of source uncertainty and estimation methods. Numerical results show that the optimal codes are, as expected, always better than Golomb-Rice codes.

关键词： adaptive coding Uncertainty Image coding Context modeling Cost function Robustness Maximum likelihood estimation Bayesian methods Convergence Parameter estimation

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On asymptotically optimal methods of prediction and adaptive coding

On asymptotically optimal methods of prediction and adaptive...

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IEEE International Symposium on Information Theory

作者： B. Ryabko F. Topsoe Siberian State Academy of Telecommunications Novosibirsk Russia Department of Mathematics University of Copenhagen Denmark

The problem of predicting a sequence x/sub 1/,x/sub 2/, generated by a discrete source with unknown statistics is considered. Each letter x/sub t+1/ is predicted using information on the word x/sub 1/x/sub 2//spl middot//spl middot//spl middot/x/sub t/ only. To estimate the efficiency of a method of prediction, three quantities are considered: the precision as given by the Kullback-Leibler divergence, the memory size of the program needed to implement the method on a computer and the average time required, measured by the number of binary operations for the prediction of a single letter. A method is presented for which the memory size and the average time is close to the minimum. The results can readily be translated to adaptive coding.

关键词： adaptive coding Statistics Frequency Time measurement Prediction methods Game theory Mathematics Size measurement Information theory Probability

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Capacity of cellular dynamic channel assignment schemes employing adaptive modulation and coding

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ELECTRONICS LETTERS 2001年第2期37卷 101-102页

作者： Pearce, DAJ Burr, AG Tozer, TC Univ York Dept Elect York YO10 5DD N Yorkshire England

An investigation into the benefits of introducing adaptive modulation and coding techniques into a cellular system employing dynamic channel assignment is performed for the case of a fixed wireless access network conveying fixed-bandwidth information. It is shown that in the typical cases considered, the introduction of adaptive modulation and coding can actually reduce the capacity of the system.

关键词： fixed wireless access network cellular dynamic channel assignment schemes Mobile radio systems Radio access systems fixed-bandwidth information radio access networks cellular radio channel capacity adaptive modulation channel allocation Information theory Communication system theory adaptive coding Modulation and coding methods system capacity reduction adaptive codes

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adaptive TRANSFORM coding OF SPEECH SIGNALS

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IEEE TRANSACTIONS ON ACOUSTICS SPEECH AND SIGNAL PROCESSING 1977年第4期25卷 299-309页

作者： ZELINSKI, R NOLL, P BELL TEL LABS INC MURRAY HILLNJ 07974 HEINRICH HERTZ INST BERLINFED REP GER

This paper discusses speech coding systems based upon transform coding (TC). It compares several transforms and shows that the cosine transform leads to a nearly optimum performance for almost all speech sounds. Various adaptive coding strategies are then investigated, and a coding scheme is proposed that is based on a nonadaptive discrete cosine transform (DCT), on an adaptive bit assignment, and on adaptive quantization. The adaptation is controlled by a short-term basis spectrum that is derived from the transform coefficients prior to coding and transmission and that is transmitted as side information to the receiver. The main result is that this adaptive transform coder performs better than all known nonpitch-tracking coding schemes; it extends the range of speech waveform coding to lower bit rates and closes the gap between vocoders and predictive waveform coders.

关键词： Transform coding Speech coding Discrete transforms Quantization Acoustic distortion Fast Fourier transforms Signal analysis Digital signal processing adaptive coding Discrete cosine transforms

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SURVEY OF adaptive IMAGE-coding TECHNIQUES

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IEEE TRANSACTIONS ON COMMUNICATIONS 1977年第11期25卷 1275-1284页

作者： HABIBI, A TRW DEF & SPACE SYST GRP REDONDO BEACHCA 90274

The following is a survey of the technical literature on adaptive coding of imagery. Section 1 briefly discusses the general problem of image data compression. The optimum image data compression system, from a theoretical viewpoint, is presented in Section 1.1. The theoretical and the implementational problems of the optimum system are discussed and the assumptions that are made to overcome these problems are outlined. One important assumption is the stationarity which is not true for most imagery. In adaptive systems the parameters are varied according to changes in signal statistics optimizing the system performance for nonstationary signals. In this article the adaptive systems are divided to four categories. Section 2 is a survey of adaptive transform coding systems. Section 3 discusses adaptive predictive coding systems. Sections 4 and 5 discuss adaptive cluster coding and adaptive entropy technique, respectively.

关键词： Image coding Karhunen-Loeve transforms adaptive systems Data compression Image converters adaptive coding Entropy Image sampling Quantization Autocorrelation

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