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Information Theory and Applications Workshop, ITA

作者： Jason D. Ellis Michael A. Juang Michael B. Pursley Clemson University USA

Packet radio systems that communicate over channels with slow fading experience changes in propagation loss from one packet to the next. In order to maintain high throughput, it is necessary for the packet radios to adapt their transmissions in response to changes in the channel. Practical adaptive coding protocols can respond to such changes by adjusting the code rate to maximize the expected throughput for each packet transmission. Performance evaluations for practical protocols typically require simulation of both the time-varying fading process and the adaptive protocol. We employ recently developed finite-state Markov models of Nakagami-m fading to obtain analytical evaluations of the throughput of an adaptive coding protocol. In our approach, neither the fading processes nor their Markov models are simulated.

关键词： Protocols Fading Throughput Adaptation models Markov processes Analytical models adaptive coding

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A FAST-adaptive HUFFMAN coding ALGORITHM

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IEEE TRANSACTIONS ON COMMUNICATIONS 1993年第4期41卷 535-538页

作者： LU, WW GOUGH, MP School of Engineering and Applied Sciences University of Sussex Brighton UK

The Huffman code in practice suffers from two problems: the prior knowledge of the probability distribution of the data source to be encoded is necessary, and the encoded data propagate errors. The first problem can be solved by an adaptive coding, while the second problem can be partly solved by segmenting data into segments. But the adaptive Huffman code performs badly when segmenting data into relatively small segments because of its relatively slow adaptability. This paper offers a fast-adaptive coding algorithm which tracks the local data statistics more quickly, thus yielding better compression efficiency.

关键词： Huffman coding adaptive coding Statistics Probability distribution Statistical distributions Bit rate Data compression Entropy Counting circuits Frequency

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Cross-layer queueing analysis for aggregated ON-OFF arrivals with adaptive modulation and coding

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IET COMMUNICATIONS 2016年第17期10卷 2336-2343页

作者： Han, Xingyu Schormans, John Queen Mary Univ London Dept Elect Engn & Comp Sci London E1 4PH England

Packet loss and delay in wireless networks is a function of both the traffic characteristics (e.g. load, burstiness) and the characteristic behaviour of the fading channel. In this study, the authors propose and analyse a new queue model in which the server process is controlled by the adaptive modulation and coding (AMC) algorithm, and with aggregated ON-OFF packet arrivals to a finite buffer. In the scenarios, where users require multiple services, aggregated ON-OFF arrivals approximate bursty behaviour better than the Poisson arrivals analysed in many earlier queueing models. They focus on the packet drop probability, the packet loss probability, the average queueing delay and the throughput, showing significant differences in these metrics between the cross-layer models using aggregated ON-OFF arrivals and Poisson arrivals. This indicates that in wireless packet network performance evaluation, the traffic model is at least as important as the effect of the fading channel modelling.

关键词： queueing theory adaptive modulation adaptive codes telecommunication traffic fading channels packet radio networks cross-layer queueing analysis adaptive coding packet delay wireless networks server adaptive modulation and coding algorithm Poisson arrivals queueing models packet drop probability packet loss probability wireless packet network fading channel modelling

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Enhanced multiuser resource allocation using near-continuous loading algorithms with adaptive coding for digital subscriber loops

Enhanced multiuser resource allocation using near-continuous...

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Canadian Conference on Electrical and Computer Engineering (CCECE)

作者： S. Panigrahi Yang Xu Tho Le-Ngoc Department of Electrical and Computer Engineering McGill University Montreal QUE Canada

In this paper, we present a multi-user resource allocation technique for multi-carrier digital subscriber loop (DSL) systems using an adaptive coding/modulation scheme. Traditional bit loading based on only adaptive modulation requires the number of bits to be integer and hence causes granularity loss that can be significant in dynamic spectrum management (DSM) when each user's sub-carrier-specific power is implicitly constrained due to other user's rate demand. By adaptively varying the code rate of a programmable Reed Solomon (RS) code, a fine-granularity loading in conjunction with the purely distributed iterated water filling (IWF) is proposed to recover such granularity losses. Simulation results for various VDSL-DMT scenarios show that the proposed scheme can provide higher rates than the distributed IWF and centralized optimum spectrum management (OSM) with integer-bit loading

关键词： Resource management adaptive coding DSL Radio spectrum management Reed-Solomon codes OFDM modulation Filling Crosstalk Background noise Digital modulation

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Analysis of wireless transmission efficiency and its application: efficiency-based adaptive coding

Analysis of wireless transmission efficiency and its applica...

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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)

作者： Xiang Duan Xiyan Ma Zhisheng Niu Junli Zheng Department of Electronic Engineering Tsinghua University Beijing China

ISBN: (纸本)0780378229

Transmission efficiency, defined as the ratio of successfully transmitted information bits to overall bits transmitted, can be used for evaluating the transmission performance of wireless links. As a function of received signal to noise ratio (SNR), transmission efficiency is determined by physical layer technologies, such as channel coding, interleaving, modulation and other error-recovery techniques of wireless links. In this paper we first analyze the form of transmission efficiency function in wireless links, then based on that we propose an adaptive coding scheme that maximizes the transmission efficiency according to wireless channel conditions (received SNR). Simulation results show that with the proposed adaptive coding, transmission efficiency of wireless links can be significantly enhanced.

关键词： adaptive coding Physical layer Interleaved codes Modulation coding Signal to noise ratio Bit error rate Decoding Channel coding Computer errors Error analysis

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A Note on adaptive coding Scheme for Improvement of Reference Tracking in Wireless Feedback Control Systems

A Note on Adaptive Coding Scheme for Improvement of Referenc...

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Annual Conference of the IEEE Industrial Electronics Society

作者： Shingo HATTORI Kentaro KOBAYASHI Hiraku OKADA Masaaki KATAYAMA Graduate School of Engineering Nagoya University EcoTopia Science Institute Nagoya University

ISBN: (纸本)9781479902255

In wireless feedback control systems, it is important how to reduce packet losses. If channel coding is used, packet losses may decrease. But its redundancy decreases the packet transmission rate under the same bit rate, so that disturbances in the controlled plant may deteriorate the quality of the control system. To improve the quality of the control system, the channel coding should be used adaptively based on packet losses and disturbances. In this paper, we propose an adaptive coding scheme based on the quality of the communication layer and the control (application) layer. In this scheme, the channel coding is used adaptively based on a predicted state of the controlled plant under a packet loss rate. We show that the proposed adaptive coding improves the control quality compared with that of the fixed rate coding.

关键词： adaptive coding Wireless control State prediction Feedback control adaptive coding wireless remote control Packet loss Channel coding feedback control Feedback control systems Quality Control control systems Bit rate Plant control

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Block-based segmentation and adaptive coding for visually lossless compression of scanned documents

Block-based segmentation and adaptive coding for visually lo...

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IEEE International Conference on Image Processing

作者： Xin Li Shawmin Lei Digital Video Department Sharp Laboratories of America Inc.orporated Camas WA USA

This paper presents a novel block-based segmentation and adaptive coding (BSAC) algorithm for visually lossless compression of scanned documents that contain not only photographic images but also text and graphic images. For such a compound image source, we structure the image into nonoverlapping blocks and classify each block into four different classes based on the empirical statistics within the block. Different coding strategies are applied to different classes in order to achieve the very best compression performance. Our new block-based image coder is able to provide visually lossless compression of scanned documents at the bit rate of around 1/spl sim/1.5 bpp with modest computational complexity and very low memory requirement.

关键词： adaptive coding Image coding Image segmentation Image resolution Graphics Bit rate Spatial resolution Decoding Video compression Statistics

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Combine adaptive Modulation and adaptive coding for Space-time Block Coded Systems

Combine Adaptive Modulation and Adaptive Coding for Space-ti...

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IEEE Region 10 International Conference TENCON

作者： YingRao Wei M.Z. Wang Department of Electronic and Information Engineering Hong Kong Polytechnic University Hong Kong China

In this paper, we propose an adaptive scheme that changes the modulation mode and the space-time block code (STBC) pattern for a space-time block coded (STBCed) system with transmit antenna selection. This scheme aims to increase the transmission throughput at certain target bit error rate (BER) with variable transmission power. Simulation results have shown that there is a trade-off between the average spectral efficiency (ASE) and BER performances. The ASE and BER can be adjusted by several parameters such as the transmission power, receive signal-to-noise ratio (SNR) threshold values to meet the requirement

关键词： Modulation coding adaptive coding Transmitting antennas MIMO Bit error rate Block codes adaptive arrays Receiving antennas Power system modeling Throughput

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A New Image Compression Scheme Based on Locally adaptive coding

A New Image Compression Scheme Based on Locally Adaptive Cod...

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IEEE International Symposium on Multimedia

作者： Chin-Chen Chang Yung-Chen Chou Chia-Chen Lin Department of Computer Science and Information Engineering National Chung Cheng University Chiayi Taiwan Department of Information Engineering and Computer Science Feng Chia University FCU Taichung Taiwan Department of Computer Science and Information Management Providence University Taichung Taiwan

ISBN: (纸本)9780769530581;0769530583

Vector quantization (VQ) is a simple and widely used compression technology in many applications. For image compression, VQ provides both a fixed compression ratio and maintains acceptable distortion. However, the performance of VQ still can be improved in terms of the image quality of compressed images and codebook size used for encoding and decoding. In this paper, a new VQ-like image compression method is proposed to improve the performance of traditional VQ by using locally adaptive coding concept. The experimental results confirm that the image quality of the compressed image offered by the proposed method is higher than 30 dB on average, and the number of codewords used in our codebook is less than that required by traditional VQ.

关键词： Image coding adaptive coding Image quality Vector quantization Computer science Application software Frequency domain analysis Clustering algorithms Pixel Histograms

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An adaptive coding scheme for mobile radio systems

An adaptive coding scheme for mobile radio systems

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IEEE Conference on Vehicular Technology (VTC)

作者： R.H. Deng H. Zhou Department of Electrical Engineering National University of Singapore Singapore

An adaptive error-control coding scheme for binary digital FM mobile radio transmission is proposed. The scheme uses code combining through packet retransmissions. The number of transmissions of a packet is proportional to the channel fading/noise levels, which is in contrast to time diversity techniques where a fixed number of repetitions of a data packet is performed even in the absence of channel errors. Furthermore, the receiver uses received signal envelopes as channel state information which significantly improves the throughput and bit error rate (BER) performance. Performance of the proposed scheme is analyzed for Rayleigh fading channels with additive white Gaussian noise (AWGN), cochannel interference, and random FM noise.< >

关键词： adaptive coding Land mobile radio Fading Bit error rate Additive white noise AWGN adaptive systems Noise level Diversity reception Channel state information

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