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IEEE Conference on Vehicular Technology (VTC)

作者： H. Rohling R. Grunheid Institute of Telecommunications Technical University of Braunschweig Germany

The capacity of a wireless communication system based on the OFDM transmission technique is analysed. The considered system, which includes a TDMA approach, is designed for mobile access to different multimedia services, such as speech, video, e-mail and file transfer. In order to support a variety of services on the one hand and to take into account the behaviour of the frequency-selective radio channel on the other hand, an adaptive allocation of modulation and coding scheme is supplied. For this purpose, an optimal combination of modulation scheme and code rate is determined in a first step. Using these results, the capacity of such a system is analysed by calculating the number of supported users within a cell and comparing these numbers to a system with fixed modulation/coding.

关键词： adaptive coding Modulation coding Speech analysis Time division multiple access OFDM modulation Electronic mail Radio spectrum management Bandwidth Videoconference Downlink

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adaptive coding of DCT coefficients by Golomb-Rice codes

Adaptive coding of DCT coefficients by Golomb-Rice codes

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IEEE International Conference on Image Processing

作者： N. Memon Computer Science Department Polytechnic University Brooklyn NY USA

In this paper we apply some of the Golomb-Rice coding techniques that emerged in JPEG-LS, a new standard for lossless image compression, and apply them towards coding DCT coefficients in the lossy JPEG baseline algorithm. We show that this results in significant improvements in performance with limited impact on computational complexity. In fact, one significant reduction in complexity provided by the proposed techniques is the complete elimination of the Huffman tables in JPEG baseline which can be a bottleneck in hardware implementations. We give simulation results, comparing the performance of the proposed technique to JPEG baseline, JPEG baseline with optimal Huffman coding (two pass) and JPEG arithmetic.

关键词： adaptive coding Discrete cosine transforms Image coding Transform coding Huffman coding Arithmetic Hardware Computational complexity ISO standards Standards development

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adaptive coding for fading channels using outdated channel estimates

Adaptive coding for fading channels using outdated channel e...

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IEEE Conference on Vehicular Technology (VTC)

作者： D.L. Goeckel Electrical and Computer Engineering Department University of Massachusetts Amherst MA USA

The development of adaptive trellis coded modulation schemes for communication systems operating over time-varying Rayleigh fading channels is considered. If the system employs a single outdated noiseless channel estimate and is able to achieve perfect interleaving of the coded symbols, substantial throughput gains are observed over non-adaptive trellis coded modulation schemes for systems with low user mobility. Next, the effect of noise in the channel estimates is shown to be an important consideration, even at the relatively high signal-to-noise ratios considered here. Finally, a bound to the pairwise error probability between two paths in the trellis of the adaptive scheme is derived analytically for the case where the coded symbols are imperfectly interleaved; this result suggests that adaptive signaling may be a strong candidate for systems operating in an environment that has limited diversity available.

关键词： adaptive coding Fading Time varying systems Channel estimation Frequency estimation Rayleigh channels Modulation coding Data communication Interleaved codes Throughput

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The prevention of error propagation in dictionary compression with update and deletion

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PROCEEDINGS OF THE IEEE 2000年第11期88卷 1713-1721页

作者： Storer, JA Brandeis Univ Dept Comp Sci Waltham MA 02254 USA

In earlier work, we presented the k-error protocol, a technique for protecting a dynamic dictionary lossless data compression method from error propagation as the result of errors on the communication channel or compressed file. In the worst case, the protocol only protects against k errors total;however, it gives very high probability protection against a sustained error rate. Here, we further develop this protocol and present experiments showing that in practice this approach is both fast and highly effective against a noisy channel or faulty storage medium. We also address the issue of dynamically deleting strings. Although without modification most standard methods used in practice (e.g., LRU strategies) perform poorly with respect to error propagation, we propose and analyze some that are very robust, including a strategy based on leaf pruning.

关键词： adaptive coding data compression error correction coding

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The piecewise-constant image model

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PROCEEDINGS OF THE IEEE 2000年第11期88卷 1779-1789页

作者： Ausbeck, PJ Caravian Software Designs Campbell CA 95008 USA

The piecewise-constant image model (PWC) is a new technique for lossless compression of palette images. PWC is a blend of traditional scanline-oriented and newer object-based methods. Remarkably, PWC delivers the best known compression across a wide variety palette of image types while delivering translation speeds comparable to highly tuned one-dimensional methods. This paper introduces the topic of palette image coding and traces the development of the piecewise-constant model from a completely object-oriented code requiring two image passes to a high-performance scanline-oriented code.

关键词： adaptive coding arithmetic codes entropy codes image coding image representations linear-predictive coding piecewise-constant approximation run-length codes

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On the use of backward adaptation in a perceptual audio coder

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IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING 2000年第4期8卷 488-490页

作者： Rodrigues, JM Tomé, AM Univ Aveiro Dept Elect & Telecommun IEETA P-3810 Aveiro Portugal

Typically, perceptual audio coders have followed a subband or transform coding scheme with forward-adaptive quantization,In this letter we present an alternative scheme which uses backward-adaptive quantization, We di... 详细信息

关键词： adaptive coding perceptual audio coding

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Lossless compression of continuous-tone images

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PROCEEDINGS OF THE IEEE 2000年第11期88卷 1797-1809页

作者： Carpentieri, B Weinberger, MJ Seroussi, G Univ Salerno Dipartimento Informat & Applicaz RM Capocelli I-84081 Baronissi SA Italy Hewlett Packard Labs Informat Theory Res Grp Palo Alto CA 94304 USA

In this paper, we survey some of the recent advances in lossless compression of continuous-tone images. The modeling paradigms underlying the state-of-the-art algorithms, and the principles guiding their design, are d... 详细信息

关键词： adaptive coding compression standards data compression image coding lossless compression

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Proposal of a fast multialphabet dynamic arithmetic coding

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ELECTRONICS AND COMMUNICATIONS IN JAPAN PART I-COMMUNICATIONS 2000年第11期83卷 66-75页

作者： Osawa, H Suzuki, K Kato, S Yasuda, Y Canon Inc CX Project Kawasaki Kanagawa 2118501 Japan Utsunomiya Univ Fac Engn Utsunomiya Tochigi 3210912 Japan Waseda Univ Grad Sch Sci & Engn Tokyo 1690072 Japan

Image coding is discussed in two phases;one is transformation of image signals using a coding model, and the other is entropy coding which assigns a code to a transformed sequence. A well-known example of the latter is arithmetic coding. Because arithmetic coding makes dynamic adaptation rather easy, it is used in efficient entropy coding of signals, such as image signals, whose statistical characteristics vary locally. Though adaptation is an effective measure to achieve efficient coding, it requires longer processing time and larger hardware size. The authors have proposed multialphabet arithmetic coding with a 1/2(n) rate approximation, whose algorithm is simple. This arithmetic coding can be performed with an extremely small amount of multiplication, and it can be extended to adaptation simply by recalculation of cumulative approximate probability. In this article, we will propose a method that optimizes update timing in adaptation, and show that we obtained satisfactory results in efficiency and coding speed. (C) 2000 Scripta Technica.

关键词： predictive coding arithmetic coding Huffman coding adaptive coding

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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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A rate-distortion optimal scalable vertex based shape coding algorithm

A rate-distortion optimal scalable vertex based shape coding...

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

作者： G. Melnikov A.K. Katsaggelos Department of Electrical and Computer Engineering North Western University Evanston IL USA

We present a rate-distortion (RD) optimized scalable vertex-based shape coding algorithm. Following the base layer, each successive enhancement layer refines a given shape approximation by optimally (within a layer) placing new vertices and perturbing existing vertices. An efficient low entropy distortion adaptive vertex coding strategy is employed to take advantage of information available from coarser layers. Based on the chosen vertex rate and distortion definitions, a resulting enhancement layer topology is solved by executing a directed acyclic graph (DAG) shortest path algorithm. Finally, an iterative VLC optimization scheme is employed to find both the optimized scalable code and the most efficient set of parameter VLC tables.

关键词： Rate-distortion Shape Rate distortion theory Topology Entropy Iterative algorithms MPEG 4 Standard adaptive coding Research and development

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