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Congress on Image and Signal Processing, CISP

作者： Wei-hua Ai Chao-ling Shen Yun-Xian Huang Institute of Meteorology People''s Liberation Army University of Science and Technology Nanjing China

A method for achieving weather radar data compression with parallel adaptive coding is presented. Considering the specialty of it, some efficient pre-processing algorithms for the data such as coordinate transformation algorithm, scalar filter algorithm and vector field holding algorithm are given first. Then the parallel adaptive coding algorithm is used to compress the pre-processed data. Experimental results show that for the weather radar data, the proposed parallel adaptive algorithm achieves good Power Signal to Noise Ratio (PSNR) even in low bit rate and the parallel coding reduced the compression time.

关键词： Meteorological radar Data compression adaptive coding Image coding Signal processing algorithms Radar antennas Azimuth Radar scattering Weather forecasting Filters

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Lossy adaptive coding of motion vectors with global camera motion compensation

Lossy adaptive coding of motion vectors with global camera m...

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Asilomar Conference on Signals, Systems & Computers

作者： X.C. Chen N. Chaddha Computer System Laboratory University of Stanford Stanford CA USA

We propose a motion estimation and coding scheme that combines global camera motion estimation with a scene adaptive coder based on a quadtree structure with entropy-constrained vector quantization (ECVQ). Global camera motion parameters are first estimated before the local motion estimation. A quadtree structure is then constructed that finds the best block size to perform adaptive local motion estimation. Motion vectors of each block size are coded using an entropy-constrained vector quantizer specific for that block size. Our simulation results have shown that this adaptive coding algorithm has superior rate-distortion performance over the traditional fixed-block-size full-search method and the global camera motion compensation gives additional performance improvement when there is camera zoom and rotation.

关键词： adaptive coding Cameras Motion compensation Motion estimation Layout Video coding Laboratories Vector quantization Parameter estimation Rate-distortion

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Segmentation of Source Symbols for adaptive Arithmetic coding

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IEEE TRANSACTIONS ON BROADCASTING 2012年第2期58卷 228-235页

作者： Zhang, Liang Wang, Demin Zheng, Dong Commun Res Ctr Canada Ottawa ON K2H 8S2 Canada

adaptive arithmetic coding is a general technique for coding source symbols of a stochastic process based on an adaptive model. The adaptive model provides measures of the statistics of source symbols and is updated, along with encoding/decoding processes, when more encoded/decoded symbols are fed as samples to the adaptive model. The coding performance depends on how well the adaptive model fits the statistics of source symbols. If the number of source symbols is large and the number of samples is small, the adaptive model may not be able to provide valid measures of the statistics, which results in an inefficient coding performance of the adaptive arithmetic coder. To this end, this paper presents segmentation of source symbols to improve the performance of the adaptive arithmetic coder. Each source symbol is divided into several segments. Each segment is separately coded with an adaptive arithmetic coder. With this division, possible values of each segment are concentrated within a small range. Given the limited number of samples, this concentration leads to a better fit of the adaptive model to the statistics of source symbols and therefore to an improvement of the coding efficiency. The proposed coding algorithm is applied to lossless motion vector coding for video transmission as an application example to show its performance improvement and coding gains.

关键词： adaptive coding predictive coding signal representations vector quantization video coding video compression

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Estimating the number of users in TDMA networks based on redundancy of adaptive channel coding

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DIGITAL SIGNAL PROCESSING 2018年 75卷 1-12页

作者： Teimouri, Mehdi Ahmadiyan, Seyed Morteza Univ Tehran Fac New Sci & Technol Informat Theory & Coding Lab Tehran Iran

Blind identification of protocols in wireless communication networks is a critical subject in noncooperative context. In this paper, a novel method is proposed to estimate the number of active users (NoAU) in wireless time division multiple access (TDMA) networks based on the redundancy of adaptive channel coding. The proposed method, which is based on decision trees and machine learning, can also be used in adaptive coding systems to identify the number of distinct code rates employed by a single transmitter. Simulation results show that the proposed method can estimate the number of codes with accuracy around 99% in noiseless situation. Moreover, for noisy environments, reasonable accuracies compared to naive methods are obtained. (C) 2017 Elsevier Inc. All rights reserved.

关键词： adaptive coding Decision trees Machine learning Estimating number of active users Time division multiple access

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adaptive Modulation and coding for Free-Space Optical Channels

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JOURNAL OF OPTICAL COMMUNICATIONS AND NETWORKING 2010年第5期2卷 221-229页

作者： Djordjevic, Ivan B. Univ Arizona Dept Elect & Comp Engn Tucson AZ 85721 USA

adaptive modulation and coding can provide robust and spectrally efficient transmission over terrestrial free-space optical channels. Three adaptive modulation schemes are considered in this paper: (i) variable-rate variable-power adaptation, (ii) channel inversion, and (iii) truncated channel inversion schemes. It is shown that a simple channel inversion scheme performs comparable to a variable-rate variable-power adaptation scheme in the weak turbulence regime but faces significant performance degradation in the strong turbulence regime. We further study adaptive coding based on large-girth quasi-cyclic low-density parity-check- (LDPC-) coded modulation. It is shown by simulation that deep fades of the order of 30 dB and above in the regime of strong turbulence can be tolerated with the proposed scheme. It is demonstrated that communication in the saturation regime is possible with the proposed adaptive LDPC-coded modulation. We also determine the spectral efficiencies for the proposed adaptive modulation and adaptive coding schemes.

关键词： Atmospheric turbulence adaptive modulation adaptive coding Free-space optical (FSO) communications Low-density parity-check (LDPC) codes

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Modeling and low-complexity adaptive coding for image prediction residuals

Modeling and low-complexity adaptive coding for image predic...

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IEEE International Conference on Image Processing

作者： N. Merhav G. Seroussi M.J. Weinberger Hewlett Packard Laboratories Company Palo Alto CA USA

This paper elaborates on the use of discrete, two-sided geometric distribution models for image prediction residuals. After providing achievable bounds for universal coding of a rich family of models, which includes traditional image models, we present a new family of practical prefix codes for adaptive image compression. This family is optimal for two-sided geometric distributions and is an extension of the Golomb (1966) codes. Our new family of codes allows for encoding of prediction residuals at a complexity similar to that of Golomb codes, without recourse to the rough approximations used when a code designed for non-negative integers is matched to the encoding of any integer. We also provide adaptation criteria for a further simplified, sub-optimal family of codes used in practice.

关键词： Predictive models adaptive coding Image coding Context modeling Decoding Costs Laboratories Pixel Arithmetic Length measurement

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Performance of adaptive coding by selection of space-time block code matrix [3G mobile communication]

Performance of adaptive coding by selection of space-time bl...

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IEEE Conference on Vehicular Technology (VTC)

作者： S. Niida T. Inoue Y. Takeuchi Mobile Communications Laboratory KDDI Corporation Tokyo Japan

The 3G mobile communication systems are currently spreading throughout the world and high speed data services on mobile systems such as streaming video, streaming audio and video phone are being widely utilized by the public at large. As higher speed rate services are infiltrated, the provision of wider band wireless systems is expected. MIMO systems, which equip several antennas with both a transmitter and receiver, have recently been attracting much attention. Space-time coding is a technique that exploits transmission diversity and achieves high performance under a fading environment. The space-time block code (STBC) is attracting particular attention for its high performance and decoding simplicity. We propose an adaptive coding scheme using the STBC. It changes the STBC pattern and the modulation symbol according to the receiving condition. In this paper, we discuss this scheme and evaluate its throughput and transmission power performances based on simulation results using ideal propagation environments and measured data in the experiment.

关键词： adaptive coding Block codes 3G mobile communication Streaming media MIMO Receiving antennas Transmitting antennas Transmitters Fading Decoding

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Rate enhancement of BICM-OFDM with adaptive coding and modulation via a bisection approach

Rate enhancement of BICM-OFDM with adaptive coding and modul...

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IEEE Workshop on Signal Processing Advances in Wireless Communications (SPAWC)

作者： Carsten Bockelmann Dirk Wubben Karl-Dirk Kammeyer Department of Communications Engineering University of Brethemen Germany

adaptive communication is an important topic to enhance the capabilities of future communication systems. Especially in combination with Orthogonal Frequency Division Multiplexing (ODFM) bit and power loading schemes have been devised to enhance the transmit rate of communication systems. The consideration of channel coding in the optimization is an obvious requirement. In the past, though, mainly uncoded systems have been investigated allowing for further enhancements. In this paper we propose a new scheme to adapt code rate and modulation by solving the convex optimization problem based on a bisection approach in order to maximize the achievable data rate at a fixed target error rate.

关键词： adaptive coding Modulation coding Channel coding Communication systems Error analysis Bit error rate OFDM modulation AWGN Frequency domain analysis Power engineering and energy

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Lossless, near-lossless and lossy adaptive coding based on the lossless DCT

Lossless, near-lossless and lossy adaptive coding based on t...

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： S. Chokchaitam M. Iwahashi Faculty of Engineering Nagaoka University of Technology Japan

This report proposes a new coding method, which realizes lossless, near-lossless and lossy coding with a unified single algorithm. The method is based on a lifting-structured lossless DCT, which maps an "integer" input vector to also an "integer" output vector. The proposed method can be used as not only a high performance "lossless" encoder but also a "lossy" encoder compatible with conventional DCT-based methods such as JPEG and MPEG. In addition, it has a "near-lossless" mode in which compression ratio is better than lossless mode retaining quite good quality of decoded images. In "lossless" mode, only the lossless DCT and an entropy coder are used. In "lossy" mode, transformed coefficients are quantized and then entropy coded in the same manner as the conventional method for compatibility. In "near-lossless" mode, signals are quantized before DCT to avoid SNR degradation due to "rounding" operations in the lossless DCT.

关键词： adaptive coding Discrete cosine transforms Image coding Decoding Entropy Transform coding Performance loss Degradation Quantization Digital images

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Channel adaptive coding techniques through application of higher order moments

Channel adaptive coding techniques through application of hi...

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IEEE International Symposium on Information Theory

作者： W.A. Clarke L. Fouche A.S.J. Helberg H.C. Ferreira Laboratory for Cybernetics Rand Afrikaans University Auckland Park South Africa Laboratory for Cybernetics Rand Afrikaans University South Africa

We investigate the use of higher order code word moments to shape the power spectral density of codes. Several codes are presented that combine different spectral shaping techniques. The insertion/deletion and additive error correcting capabilities of these codes are investigated and simple decoding procedures are presented. Finally, we give an example for the use of a higher order spectral zero code.< >

关键词： adaptive coding Error correction codes Frequency Bandwidth Laboratories Cybernetics Africa Decoding Block codes Speech coding

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