While digital coding provides us with numerous benefits, it does have some shortcomings, namely the threshold and the leveling-off effects. These problems do not occur with the use of analog coding, however. Hybrid digital-analog coding systems use both digital and analog coding at the same time to take advantage of the strengths of both coding schemes, while avoiding the problems associated with each. In this work, we propose an HDA system for coding correlates sources. We find the optimal power allocation between the digital and analog parts, and verify the advantages of the suggested system by comparing it to its digital and analog counterparts under different scenarios.
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.
With the end of Moore’s Law, domain-specific architecture (DSA) has become a crucial mode of implementing future computing architectures. This book discusses the system-level design methodology of DSAs and their applications, providing a unified design process that guarantees functionality, performance, energy efficiency, and real-time responsiveness for the target application. DSAs often start from domain-specific algorithms or applications, analyzing the characteristics of algorithmic applications, such as computation, memory access, and communication, and proposing the heterogeneous accelerator architecture suitable for that particular application. This book places particular focus on accelerator hardware platforms and distributed systems for various novel applications, such as machine learning, data mining, neural networks, and graph algorithms, and also covers RISC-V open-source instruction sets. It briefly describes the system design methodology based on DSAs and presents the latest research results in academia around domain-specific acceleration architectures. Providing cutting-edge discussion of big data and artificial intelligence scenarios in contemporary industry and typical DSA applications, this book appeals to industry professionals as well as academicians researching the future of computing in these areas.
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.
Visual information is one of the richest and most bandwidth-consuming modes of communication. To meet the requirements of emerging applications, powerful data compression and transmission techniques are required to achieve highly efficient communication, even in the presence of growing communication channels that offer increased bandwidth. Presenting the results of the author’s years of research on visual data compression and transmission, Advances in Visual Data Compression and Communication: Meeting the Requirements of New Applications provides a theoretical and technical basis for advanced research on visual data compression and communication. The book studies the drifting problem in scalable video coding, analyzes the reasons causing the problem, and proposes various solutions to the problem. It explores the author’s Barbell-based lifting coding scheme that has been adopted as common software by MPEG. It also proposes a unified framework for deriving a directional transform from the nondirectional counterpart. The structure of the framework and the statistic distribution of coefficients are similar to those of the nondirectional transforms, which facilitates subsequent entropy coding. Exploring the visual correlation that exists in media, the text extends the current coding framework from different aspects, including advanced image synthesis—from description and reconstruction to organizing correlated images as a pseudo sequence. It explains how to apply compressive sensing to solve the data compression problem during transmission and covers novel research on compressive sensor data gathering, random projection codes, and compressive modulation. For analog and digital transmission technologies, the book develops the pseudo-analog transmission for media and explores cutting-edge research on distributed pseudo-analog transmission, denoising in pseudo-analog transmission, and supporting MIMO. It concludes by considering emerging developments of information theory for future applications.
MOBILE TERMINAL RECEIVER DESIGN MOBILE TERMINAL RECEIVER DESIGN LTE and LTE-Advanced India This all-in-one guide addresses the challenges of designing innovative mobile handset solutions that offer smaller size, low power consumption, low cost, and tremendous flexibility, with improved data rates and higher performance. Readers are introduced to mobile phone system architecture and its basic building blocks, different air interface standards and operating principles, before progressing to hardware anatomy, software and protocols, and circuits for legacy and next-generation smart phones, including various research areas in 4G and 5G systems. Mobile Terminal Receiver Design/p? ulliexplains basic working principles, system architecture and specification detailsof legacy and possible next-generation mobile systems, from principle to practiceto product; covers in detail RF transmitter and receiver blocks, digital baseband processingblocks, receiver and transmitter signal processing, protocol stack, AGC, AFC, ATC,power supply, clocking; features important topics like connectivity and application modules with differentdesign solutions for tradeoff exploration; discusses multi-RAT design requirements, key design attributes such as low powerconsumption, slim form factors, seamless I-RAT handover, sensitivity, and selectivity. It will help software, hardware, and radio frequency design engineers to understand the evolution of radio access technologies and to design competitive and innovative mobile solutions and devices. Graduates, postgraduate students, and researchers in mobile telecommunications disciplines will also find this book a handy reference.
DCC is international conference for current work on data compression for text, images, video, audio, and related areas. The proceedings cover topics such as lossless and lossy compression algorithms for specific types of data, source coding, joint source-channel coding, multiple description coding, quantization theory, vector quantization, encoding with wavelets, bi-level image compression, video compression, source coding in multiple access networks, parallel compression algorithms and hardware, and fractal based methods.
