Analog Joint Source Channel Coding for Multi Terminal and Non-linear Channels
Analog Joint Source Channel Coding for Multi Terminal and Non-linear Channels

Author: Mohamed K. Hassanin

Publisher:

Published: 2018

Total Pages: 119

ISBN-13: 9780438595552

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This dissertation discusses various problems in analog Joint Source Channel Coding (JSCC). Analog JSCC is an attractive communication scheme due to its encoding/decoding simplicity, and its ability to achieve near-optimal performance using very short code lengths. JSCC systems have received a renewed interest in recent years due to, among other factors, the sub-optimality of separation based schemes in many situations in multi-terminal communications. Different from traditional digital communication systems which utilize a quantizer followed by a source code and a channel code, analog JSCC systems combine source and channel coding into a single block and deal with real numbers. ☐ We present original work on the application of space filling curves, a common scheme in analog coding, to different communication scenarios. We begin by examining how to extend the use of space filling curves to non-linear channels with Inter-Symbol Interference (ISI). This type of channel arises when considering acoustic communications in the underwater environment, where the power amplifier used for communication is highly non-linear, and multi-path propagation causes ISI. We first study a simplified version of the acoustic channel assuming a frequency flat (no ISI) response, developing a scheme to adapt space filling curves to the simplified channel and studying its theoretical limits. Then, we extend our work to the complete end-to-end acoustic channel (including ISI), presenting a communication system for the end-to-end channel. ☐ We then investigate the problem of transmitting independent sources over the Gaussian Multiple Access Channel (MAC). The Gaussian MAC consists of two or more users communicating information to a central receiver over a shared noisy physical channel. We introduce an analog CDMA-like access scheme that allows users to transmit at different rates over the MAC. The developed access scheme is suitable for the transmission of analog JSCC encoded sources. The CDMA-like access scheme will be proven to be optimal for a particular case when the channel degrees of freedom are assigned amongst the users in a particular way. We will then present a hybrid analog-digital scheme which is an extension of the analog CDMA-like access scheme. The hybrid scheme uses analog and digital codes, designed for the point-to-point channel, and will be proven to be optimal for the entire region of the MAC. ☐ Finally, the dissertation introduces a new communication scheme for the two-user Gaussian Broadcast channel. The channel consists of a common transmitter wishing to communicate information to two receivers over a noisy Gaussian channel. The broadcast channel is an interesting case, since in general separation based schemes cannot achieve the theoretical limits. The new developed scheme is a variant of Scalar Quantizer Linear Coder (SQLC) systems, and is suitable for transmitting correlated Bivariate Gaussian sources. The scheme will be analyzed and shown to outperform the best known separation based schemes.

Analog Non-linear Coding for Improved Performance in Compressed Sensing
Analog Non-linear Coding for Improved Performance in Compressed Sensing

Author: Yichuan Hu

Publisher:

Published: 2009

Total Pages:

ISBN-13: 9781109386561

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We propose a framework based on the combination of compressed sensing and non-linear coding that shows excellent robustness against noise. The key idea is the use of non-linear mappings that act as analog joint source-channel encoders, processing the compressed sensing measurements proceeding from an analog source and producing continuous amplitude samples that are transmitted directly through the noisy channel. Specifically, we first investigate analog joint source-channel coding systems using space-filling curves and MMSE decoding. At the encoder, N source symbols are mapped into K channel symbols directly, achieving either bandwidth compression (N> K) or expansion (N

Joint Source-channel Coding Of Discrete-time Signals With Continuous Amplitudes
Joint Source-channel Coding Of Discrete-time Signals With Continuous Amplitudes

Author: Norbert Goertz

Publisher: World Scientific

Published: 2007-09-21

Total Pages: 207

ISBN-13: 1908979143

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This book provides the first comprehensive and easy-to-read discussion of joint source-channel encoding and decoding for source signals with continuous amplitudes. It is a state-of-the-art presentation of this exciting, thriving field of research, making pioneering contributions to the new concept of source-adaptive modulation.The book starts with the basic theory and the motivation for a joint realization of source and channel coding. Specialized chapters deal with practically relevant scenarios such as iterative source-channel decoding and its optimization for a given encoder, and also improved encoder designs by channel-adaptive quantization or source-adaptive modulation.Although Information Theory is not the main topic of the book — in fact, the concept of joint source-channel coding is contradictory to the classical system design motivated by a questionable practical interpretation of the separation theorem — this theory still provides the ultimate performance limits for any practical system, whether it uses joint source-channel coding or not. Therefore, the theoretical limits are presented in a self-contained appendix, which is a useful reference also for those not directly interested in the main topic of this book./a

Joint Source and Channel Coding
Joint Source and Channel Coding

Author: James L. Massey

Publisher:

Published: 1977

Total Pages: 17

ISBN-13:

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The advantages and disadvantages of combining the functions of source coding ('data compression') and channel coding ('error correction') into a single coding unit are considered. Particular attention is given to linear encoders, both for sources and for channels, because their ease of implementation makes their use desirable in practice. It is shown that, without loss of optimality, a joint source/channel linear encoder may be used when the goal is the distortionless reproduction of the source at the destination. On the other hand, it is shown that in general there is an inherent and significant loss of optimality if a joint source/channel linear encoder is used when the goal is relaxed to reproduction of the source within some specified non-negligible distortion. (Author).

Joint Source-Channel Decoding
Joint Source-Channel Decoding

Author: Pierre Duhamel

Publisher: Academic Press

Published: 2010-01-07

Total Pages: 344

ISBN-13:

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Gives the tools to develop applications in video broadcasting with the improved quality of service offered by joint-source channel decoding.

Joint Source Channel Coding in Broadcast and Relay Channels
Joint Source Channel Coding in Broadcast and Relay Channels

Author: James Ho

Publisher:

Published: 2013

Total Pages: 103

ISBN-13:

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The paradigm of separate source-channel coding is inspired by Shannon's separation result, which implies the asymptotic optimality of designing source and channel coding independently from each other. The result exploits the fact that channel error probabilities can be made arbitrarily small, as long as the block length of the channel code can be made arbitrarily large. However, this is not possible in practice, where the block length is either fixed or restricted to a range of finite values. As a result, the optimality of source and channel coding separation becomes unknown, leading researchers to consider joint source-channel coding (JSCC) to further improve the performance of practical systems that must operate in the finite block length regime. With this motivation, this thesis investigates the application of JSCC principles for multimedia communications over point-to-point, broadcast, and relay channels. All analyses are conducted from the perspective of end-to-end distortion (EED) for results that are applicable to channel codes with finite block lengths in pursuing insights into practical design. The thesis first revisits the fundamental open problem of the separation of source and channel coding in the finite block length regime. Derived formulations and numerical analyses for a source-channel coding system reveal many scenarios where the EED reduction is positive when pairing the channel-optimized source quantizer (COSQ) with an optimal channel code, hence establishing the invalidity of the separation theorem in the finite block length regime. With this, further improvements to JSCC systems are considered by augmenting error detection codes with the COSQ. Closed-form EED expressions for such system are derived, from which necessary optimality conditions are identified and used in proposed algorithms for system design. Results for both the point-to-point and broadcast channels demonstrate significant reductions to the EED without sacrificing bandwidth when considering a tradeoff between quantization and error detection coding rates. Lastly, the JSCC system is considered under relay channels, for which a computable measure of the EED is derived for any relay channel conditions with nonzero channel error probabilities. To emphasize the importance of analyzing JSCC systems under finite block lengths, the large sub-optimality in performance is demonstrated when solving the power allocation configuration problem according to capacity-based formulations that disregard channel errors, as opposed to those based on the EED. Although this thesis only considers one JSCC setup of many, it is concluded that consideration of JSCC systems from a non-asymptotic perspective not only is more meaningful, but also reveals more relevant insight into practical system design. This thesis accomplishes such by maintaining the EED as a measure of system performance in each of the considered point-to-point, broadcast, and relay cases.

On Robust and Energy-limited Joint Source-channel Coding
On Robust and Energy-limited Joint Source-channel Coding

Author: Erman Koken

Publisher:

Published: 2017

Total Pages: 108

ISBN-13: 9780355472646

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In this thesis we investigate the lossy transmission of single and bivariate Gaussian sources over bandwidth-mismatched additive Gaussian white noise and broadcast channels. For these scenarios we proposed novel hybrid digital/analog based joint source-channel coding schemes which generalize or outperform existing schemes. In the first scenario we assume that side information is available at the receiver, channel state information of additive interference is available at the transmitter, and power is limited. For this scenario we proposed hybrid digital/analog schemes, for both bandwidth expansion and bandwidth compression cases, which can attain the optimum reconstruction levels. For bandwidth expansion we showed that the scheme can attain optimum distortion levels for a set of receivers with different side information and channel qualities simultaneously with a single set of scheme parameters. In the second scenario, where no side information or interference are present, we consider the robustness of scheme where it must attain the optimal distortion at a target signal-to-noise-ratio and we would like to attain the best distortion pair for two possible receivers one with better and the other with worse channel quality. We extended Tian et al.'s result to a set of non-integer bandwidth expansion ratios. Then we investigate the transmission of bivariate sources over broadcast channels. For this scenario we proposed a scheme which outperforms the known schemes which are either purely digital or hybrid schemes. Finally we analyzed energy-distortion tradeoff for lossy transmission of a Gaussian source over bandwidth-unlimited channel. We performed asymptotical analyses as signal- to-noise-ratio goes to infinity. We also considered zero-delay transmission of the source.

Combined Source-Channel Coding for Bandlimited Waveform Channels
Combined Source-Channel Coding for Bandlimited Waveform Channels

Author:

Publisher:

Published: 1989

Total Pages:

ISBN-13:

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We consider the problem of transmitting data from a continuous- ampltude, discrete-time source over a bandlimited waveform channel using a block-structured digital communication system. Our objective is to design the source encoder-decoder pair, the channel encoder-decoder pair and the modulator-demodulator pair so as to minimize a squared-error distortion measure betweent he source sequence and its replica in the receiver, subject to constrainsts on the transmitted signal power and bandwidth. We formulate the problem i a gneral sense and derive necessary conditions for optimality for the design variables, namely, the encorder map, the decoder map and the modulation signal set. We then consider two systems for which the necessary condition for optimality hold. The receiver of the first system consists of an unquantized soft-decision demodulator followed by a linear estimator-based decoder. We solve the necessary conditions for optimality using an iterative soution technique. We then study the perofrmance of this class of systems as the encoding rate increases, for a fixed bandwidth. Performance comparisons are made against a reference system as well as bounds from information theory. Significant improvements over the reference system are demonstrated and the performance is shown to coincide with an information-theoretic bound in two cases. The receiver of the second system consists of a quantized demodulator followed by an optimum decoder. For a fixed signal set, the optimal encoder and decoder conditions are solved using an iterative solution technique. Performance comparisons are made against the linear estimator-based system, the reference ystem and bounds from information theory. We then study the quantized demodulator- based system as the encoding rate becomes large, for a fixed bandwidth. We demonstrate that this system converges to a lienar analog modulation system in some cases to a nonlinear analog modulation system in others. Finally, we study the perform

A Hybrid Analog-digital Coding Scheme for Digital Sources
A Hybrid Analog-digital Coding Scheme for Digital Sources

Author: Lu Li

Publisher:

Published: 2018

Total Pages: 115

ISBN-13: 9780438600409

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Traditional analog and digital coding systems present their own advantages and constraints. Digital systems show excellent BER performance, but optimizing them over a wide range of signal to noise ratios (SNR) requires switching between different systems (e.g., adaptive coding). Analog systems allow high throughput communications over a wide dynamic range, but their bit error rate (BER) performance is not as good as in digital schemes. The aim of this work is to explore how to overcome these drawbacks by properly integrating both analog and digital systems into a hybrid one. ☐ The proposed hybrid coding scheme is realized by parallel concatenation of Rate Compatible Modulation (RCM) and a Low Density Generator Matrix (LDGM) code. RCM generates its output symbols by standard linear combinations of input bits. In addition, an LDGM code produces a few output bits. Because of dense constellation and fine-grain energy accumulation, RCM is able to achieve smooth rate adaptation, but it experiences performance degradation due to the presence of error floors. The introduction of the LDGM code allows to reduce most of the residual errors, substantially improving the system performance. ☐ This work considers the application of the hybrid scheme to point-to-point AWGN channels and to multiple access channels (MAC). For AWGN channels, our study focuses on optimizing the design for uniform and non-uniform memoryless sources. Decoding is implemented by building an appropriate graph and performing belief propagation. The influence of several design parameters on the system performance and the existing trade-offs are discussed. The proposed hybrid coding scheme achieves better performance than traditional joint source channel coding techniques in terms of gaps to the theoretical limit. We also introduce a simplified decoding technique for the proposed hybrid scheme. The idea is to treat the coded symbols as real values, and to use a Gaussian approximation, so that very simple analog message passing can be applied. This substantially reduces the decoding complexity, while the system performance does not experience significant degradation. ☐ For the MAC, a synthetic decoder structure and decoding algorithm has been developed and studied to tackle the ambiguity problem resulting from the existence of multi-level symbols proceeding from the RCM sub-block. The synthetic decoder also reduces the computational complexity by jointly considering messages propagated in the graph. As we will see, the hybrid scheme can achieve high transmission rates with good BER performance in MAC environments, even when the simplified decoding technique is applied.