Multiple Description Quantization via Gram-Schmidt Orthogonalization

The multiple description (MD) problem has received considerable attention as a model of information transmission over unreliable channels. A general framework for designing efficient multiple description quantization schemes is proposed in this paper. We provide a systematic treatment of the El Gamal-Cover (EGC) achievable MD rate-distortion region, and show that any point in the EGC region can be achieved via a successive quantization scheme along with quantization splitting. For the quadratic Gaussian case, the proposed scheme has an intrinsic connection with the Gram-Schmidt orthogonalization, which implies that the whole Gaussian MD rate-distortion region is achievable with a sequential dithered lattice-based quantization scheme as the dimension of the (optimal) lattice quantizers becomes large. Moreover, this scheme is shown to be universal for all i.i.d. smooth sources with performance no worse than that for an i.i.d. Gaussian source with the same variance and asymptotically optimal at high resolution. A class of low-complexity MD scalar quantizers in the proposed general framework also is constructed and is illustrated geometrically; the performance is analyzed in the high resolution regime, which exhibits a noticeable improvement over the existing MD scalar quantization schemes.Comment: 48 pages; submitted to IEEE Transactions on Information Theor

Zero-Delay Multiple Descriptions of Stationary Scalar Gauss-Markov Sources

In this paper, we introduce the zero-delay multiple-description problem, where an encoder constructs two descriptions and the decoders receive a subset of these descriptions. The encoder and decoders are causal and operate under the restriction of zero delay, which implies that at each time instance, the encoder must generate codewords that can be decoded by the decoders using only the current and past codewords. For the case of discrete-time stationary scalar Gauss—Markov sources and quadratic distortion constraints, we present information-theoretic lower bounds on the average sum-rate in terms of the directed and mutual information rate between the source and the decoder reproductions. Furthermore, we show that the optimum test channel is in this case Gaussian, and it can be realized by a feedback coding scheme that utilizes prediction and correlated Gaussian noises. Operational achievable results are considered in the high-rate scenario using a simple differential pulse code modulation scheme with staggered quantizers. Using this scheme, we achieve operational rates within 0.415 bits / sample / description of the theoretical lower bounds for varying description rates

Source-Channel Diversity for Parallel Channels

We consider transmitting a source across a pair of independent, non-ergodic channels with random states (e.g., slow fading channels) so as to minimize the average distortion. The general problem is unsolved. Hence, we focus on comparing two commonly used source and channel encoding systems which correspond to exploiting diversity either at the physical layer through parallel channel coding or at the application layer through multiple description source coding. For on-off channel models, source coding diversity offers better performance. For channels with a continuous range of reception quality, we show the reverse is true. Specifically, we introduce a new figure of merit called the distortion exponent which measures how fast the average distortion decays with SNR. For continuous-state models such as additive white Gaussian noise channels with multiplicative Rayleigh fading, optimal channel coding diversity at the physical layer is more efficient than source coding diversity at the application layer in that the former achieves a better distortion exponent. Finally, we consider a third decoding architecture: multiple description encoding with a joint source-channel decoding. We show that this architecture achieves the same distortion exponent as systems with optimal channel coding diversity for continuous-state channels, and maintains the the advantages of multiple description systems for on-off channels. Thus, the multiple description system with joint decoding achieves the best performance, from among the three architectures considered, on both continuous-state and on-off channels.Comment: 48 pages, 14 figure

Analysis of a Cooperative Strategy for a Large Decentralized Wireless Network

This paper investigates the benefits of cooperation and proposes a relay activation strategy for a large wireless network with multiple transmitters. In this framework, some nodes cooperate with a nearby node that acts as a relay, using the decode-and-forward protocol, and others use direct transmission. The network is modeled as an independently marked Poisson point process and the source nodes may choose their relays from the set of inactive nodes. Although cooperation can potentially lead to significant improvements in the performance of a communication pair, relaying causes additional interference in the network, increasing the average noise that other nodes see. We investigate how source nodes should balance cooperation vs. interference to obtain reliable transmissions, and for this purpose we study and optimize a relay activation strategy with respect to the outage probability. Surprisingly, in the high reliability regime, the optimized strategy consists on the activation of all the relays or none at all, depending on network parameters. We provide a simple closed-form expression that indicates when the relays should be active, and we introduce closed form expressions that quantify the performance gains of this scheme with respect to a network that only uses direct transmission.Comment: Updated version. To appear in IEEE Transactions on Networkin

Representation of Middle Eastern Culture through Belly Dance in the US

In light of the myriad misunderstandings about the Middle East and its people, this paper will seek to analyze how Middle Eastern culture has been represented in the US through the art of belly dance. This project examines what is currently known about the roots of belly dance, especially in relation to how such origins may be presented within the dance, and the first exposures that the American public may have had to belly dance through literary accounts, theatre, and design in the late 19th century and the early 20th century. The representative accuracy and impact of these different sources are discussed as well as how they relate to current representations of the Middle East used in belly dance. The presence of the dance itself in the US, beginning with the Chicago World’s Fair of 1893 through to current performances, is then examined to see how different aspects of the dance and the culture from which it came are either emphasized or neglected at different points in time. Building on literature reviews, observations of performances, and interviews with current performers, this project will demonstrate that, since the introduction of belly dance to the US, and by extension much of Western society, the dance has never been authentically Middle Eastern. It has always been subjected to American expectations, interpretations, and some gross inaccuracies, and has changed to such an extent that current performances are no longer Middle Eastern in origin as much as they are American

Topics in network information theory

Ph.DDOCTOR OF PHILOSOPH

Control of mobile networks using dynamic vehicle routing

Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 141-144).This thesis considers the Dynamic Pickup and Delivery Problem (DPDP), a dynamic multi-stage vehicle routing problem in which each demand requires two spatially separated services: pickup service at its source location and then delivery service at its destination location. The Dynamic Pickup and Delivery Problem arises in many practical applications, including taxi and courier services, manufacturing and inventory routing, emergency services, mobile sensor networks, Unmanned Aerial Vehicle (UAV) routing, and delay tolerant wireless networks. The main contribution of this thesis is the quantification of the delay performance of the Dynamic Pickup and Delivery Problem as a function of the number of vehicles, the total arrival rate of messages, the required message service times, the vehicle velocity, and the network area. Two lower bounds are derived. First, the Universal Lower Bound quantifies the impact of spatially separated service locations and system loading on average delay. The second lower bound is derived by reducing the two-stage Dynamic Pickup and Delivery Problem to the single-stage Dynamic Traveling Repairperson Problem (DTRP). Policies are then presented for which these lower bounds are tight as a function of the system scaling parameters (up to a constant). The impact of information and inter-vehicle relays is also studied. The last part of this thesis examines the application of the Dynamic Pickup and Delivery Problem to mobile multi-agent wireless networks from a physical layer perspective, seeking insights for the control of the network to achieve trade-offs between throughput and delay.by Holly A. Waisanen-Hatipoglu.Ph.D

Middle Byzantine silk in context: integrating the textual and material evidence

This work represents the most comprehensive investigation of silk in the middle Byzantine period to date. The current interpretation of silk as an imperial prerogative confined to elite use is poorly integrated with the body of evidence and lacks explanatory value. The difficult terminology and scattered mentions in written sources limits application of conventional research methods. Although a number of silk fragments survive in institutional collections, the lack of find and contextual information represents a formidable obstacle. This dissertation redefines silk in Byzantium by demonstrating its social importance, contribution to technology development, and integration in the regional economy. Findings are based on intensive analysis of production and consumption data from parallel investigation of texts and textile fragments according to a common framework. To aid data collection and analysis, information technology tools involving relational database methods and digital imaging were devised for this purpose. The evidence suggests that the historical process involving silk was shaped by a continuing cycle of elite differentiation and imitative reproduction, which contributed to the transmission of the material and production in the region. From a broader perspective, this work demonstrates the relevance of textile studies to the interpretation of economic and social history

Photonic low-cost sensors for in-line fluid monitoring. Design methodology

779 p.The paradigm of process monitoring has evolved in the last years, driven by a clear need for improving efficiency, quality and safety of processes and products. Sectors as manufacturing, energy, food and beverages, etc. are fostering the adoption of innovative methods for controlling their processes and products, in a non-destructive, in-place, reliable, fast, accurate and cost-efficient manner. Furthermore, the parameters requested by the industry for the quality assessment are evolving from basic magnitudes as pressures, temperatures, humidity, etc. to complete chemical and physical fingerprints of these products and processes. In this situation, techniques based on the UV/VIS/NIR light-matter interaction appear to be optimum candidates to face the request of the industry. Moreover, at this moment, when we are witnessing a technological revolution in the field of optoelectronic components, which are required for setting up these light-based analyzers.However, being able to integrate these optoelectronic components with the rest of subsystems (electronics, optics, mechanics, hydraulics, data processing, etc.) is not straightforward. The development of these multi-domain and heterogeneous sensor products meeting not just technological but also market objectives poses a considerable technical and organizational challenge for any company.In this context, a methodological hybrid and agile integration of photonic components within the rest of subsystems towards a sensor product development is presented as the main outcome of the thesis. The methodology has been validated in several industrial scenarios, being three of them included in this thesis, which covers from hydraulic fluid quality control to real-time monitoring of alcoholic beverage fermentation process

Integrated information theory in complex neural systems

This thesis concerns Integrated Information Theory (IIT), a branch of information theory aimed at providing a fundamental theory of consciousness. At its core, lie two powerful intuitions: • That a system that is somehow more than the sum of its parts has non-zero integrated information, Φ; and • That a system with non-zero integrated information is conscious. The audacity of IIT’s claims about consciousness has (understandably) sparked vigorous criticism, and experimental evidence for IIT as a theory of consciousness remains scarce and indirect. Nevertheless, I argue that IIT still has merits as a theory of informational complexity within complexity science, leaving aside all claims about consciousness. In my work I follow this broad line of reasoning: showcasing applications where IIT yields rich analyses of complex systems, while critically examining its merits and limitations as a theory of consciousness. This thesis is divided in three parts. First, I describe three example applications of IIT to complex systems from the computational neuroscience literature (coupled oscillators, spiking neurons, and cellular automata), and develop novel Φ estimators to extend IIT’s range of applicability. Second, I show two important limitations of current IIT: that its axiomatic foundation is not specific enough to determine a unique measure of integrated information; and that available measures do not behave as predicted by the theory when applied to neurophysiological data. Finally, I present new theoretical developments aimed at alleviating some of IIT’s flaws. These are based on the concepts of partial information decomposition and lead to a unification of both theories, Integrated Information Decomposition, or ΦID. The thesis concludes with two experimental studies on M/EEG data, showing that a much simpler informational theory of consciousness – the entropic brain hypothesis – can yield valuable insight without the mathematical challenges brought by IIT.Open Acces