Enhancing diversity and multiplexing gains in multi-user wireless relay systems

The demand for higher transmission rates and better quality of service in modern wireless communications is endless. The use of multiple transmit or /and receive antennas has been considered as one of the most powerful approaches to facilitate high -speed and high -quality communications. However, in practical cellular systems, mobile terminals may not be able to support a multiple- antenna setup. Thus an emerging technique called cooperative diversity is under consideration to utilize the multi -hop relay concept to realize the advantages of multiple - antenna systems in multi -user single- antenna networks. Cooperative diversity has attracted much interest in recent years as a very promising direction for future wireless communication evolution.Due to the fact that in practice terminals cannot transmit and receive simultaneously (i.e. the half -duplex limitation), the diversity improvement brought by the standard cooperative diversity transmission protocols is in general accompanied by a multiplexing loss (equivalent to a reduction in transmission data rate in high signal -to -nose ratio (SNR)). The purpose of this thesis is to use advanced transmission protocols to provide both good diversity and multiplexing performance when using the practical repetition -coded decode - and -forward (DF) relaying strategy in uplink mobile -to -base station transmission of cellular systems.The task is fulfilled by relaxing the orthogonal channel allocation requirement of the standard protocols and by using two relays to take turns forwarding source information to destination. We start our analysis from an M- source two -relay one -destination network. Through diversity -multiplexing tradeoff (DMT) analysis, we prove that for an isolated -relay scenario and a strong -interference scenario, the considered approach effectively recovers the multiplexing loss induced by the standard protocols while still obtaining diversity improvement over direct source -destination transmission without considering relaying.In addition, since the optimal multiplexing gain of the considered system can be achieved by the above approach, we study further improving diversity performance for a two -source network. We analyze taking full advantage of the multiple- source structure, multiple -relay structure, and the capability of affording complex signal processing at the destination (base station). For all three cases, we prove that the diversity performance of the above approach can be enhanced without a significant loss of multiplexing performance or using complex coding strategies at relays. Since the good DMT performance is not affected by source -relay channel conditions, the protocols discussed in this thesis make relaying more beneficial

Virtual-MIMO systems with compress-and-forward cooperation

Multiple-input multiple-output (MIMO) systems have recently emerged as one of the most significant wireless techniques, as they can greatly improve the channel capacity and link reliability of wireless communications. These benefits have encouraged extensive research on a virtual MIMO system where the transmitter has multiple antennas and each of the receivers has a single antenna. Single-antenna receivers can work together to form a virtual antenna array and reap some performance benefits of MIMO systems. The idea of receiver-side local cooperation is attractive for wireless networks since a wireless receiver may not have multiple antennas due to size and cost limitations. In this thesis we investigate a virtual-MIMO wireless system using the receiver-side cooperation with the compress-and-forward (CF) protocol. Firstly, to perform CF at the relay, we propose to use standard source coding techniques, based on the analysis of its expected rate bound and the tightness of the bound. We state upper bounds on the system error probabilities over block fading channels. With sufficient source coding rates, the cooperation of the receivers enables the virtual-MIMO system to achieve almost ideal MIMO performance. A comparison of ideal and non-ideal conference links within the receiver group is also investigated. Considering the short-range communication and using a channel-aware adaptive CF scheme, the impact of the non-ideal cooperation link is too slight to impair the system performance significantly. It is also evident that the practicality of CF cooperation will be greatly enhanced if a efficient source coding technique can be used at the relay. It is even more desirable that CF cooperation should not be unduly sensitive to carrier frequency offsets (CFOs). Thus this thesis then presents a practical study of these two issues. Codebook designs of the Voronoi VQ and the tree-structure vector quantization (TSVQ) to enable CF cooperation at the relay are firstly described. A comparison in terms of the codebook design complexity and encoding complexity is presented. It is shown that the TSVQ is much simpler to design and operate, and can achieve a favourable performance-complexity tradeoff. We then demonstrate that CFO can lead to significant performance degradation for the virtual MIMO system. To overcome it, it is proposed to maintain clock synchronization and jointly estimate the CFO between the relay and the destination. This approach is shown to provide a significant performance improvement. Finally, we extend the study to the minimum mean square error (MMSE) detection, as it has a lower complexity compared to maximum likelihood (ML) detection. A closed-form upper bound for the system error probability is derived, based on which we prove that the smallest singular value of the cooperative channel matrix determines the system error performance. Accordingly, an adaptive modulation and cooperation scheme is proposed, which uses the smallest singular value as the threshold strategy. Depending on the instantaneous channel conditions, the system could therefore adapt to choose a suitable modulation type for transmission and an appropriate quantization rate to perform CF cooperation. The adaptive modulation and cooperation scheme not only enables the system to achieve comparable performance to the case with fixed quantization rates, but also eliminates unnecessary complexity for quantization operations and conference link communication

Advanced Modulation and Coding Technology Conference

The objectives, approach, and status of all current LeRC-sponsored industry contracts and university grants are presented. The following topics are covered: (1) the LeRC Space Communications Program, and Advanced Modulation and Coding Projects; (2) the status of four contracts for development of proof-of-concept modems; (3) modulation and coding work done under three university grants, two small business innovation research contracts, and two demonstration model hardware development contracts; and (4) technology needs and opportunities for future missions

Quantum Uncertainty Reduction (QUR) Theory of Attended Access and Phenomenal Consciousness

In this dissertation I defend a theory of perceptual consciousness titled “Quantum Uncertainty Reduction” (QUR[1]) Theory of Attended Access and Phenomenal Consciousness.” Consciousness is widely perceived as a phenomenon that poses a special explanatory problem for science. The problem arises in the apparent rift between an immediate first-person acquaintance with consciousness and our lack of ability to provide an objective/scientific third-person characterization of consciousness. I begin by reviewing philosophical ideas of Ned Block, David Chalmers and Jesse Prinz whose characterizations of consciousness provide a conceptual framework that the proposed theory aims to satisfy. Block and Chalmers argue that consciousness is a mongrel concept combining two distinct aspects: access and phenomenal consciousness, while Jesse Prinz’s argues for the central role of attention in engendering consciousness. Since the proposed solution is an aspect of quantum information processing in a mechanism, I discuss and adopt methodological approach of the use of mechanisms in scientific explanations developed by William Bechtel, Carl Craver and others. I outline a mechanism based on Shannon Communication System and enhanced with Bayesian predictive processing developed by Carl Friston, Jacob Hohwy, and Andy Clark as well as Control Theory by Rick Grush. Based on views of Marcin Miłkowski, Gualtiero Piccinini and others on information processing in physical systems, I argue that the suggested mechanism implements physical information processing or computation. After a brief overview of relevant aspects of quantum theory, I review recent developments that aim to reconstruct quantum theory by using epistemic approach to explain the nature of quantum states vs. the traditional ontic one. I adopt the epistemic approach and argue that by performing a functional analysis of physical computation in the suggested mechanism we can identify a certain process as involving processing/manipulation of quantum and classical information. I further suggest that the central aspect of the process, namely, quantum uncertainty reduction gives rise to qualitative properties of phenomenal and access consciousness. Further, I compare the suggested information processing formulation of Access and Phenomenal consciousness with those of Block and Chalmers, that are, correspondingly, non-functional and non-physical. I argue that my conceptualization is preferable since it gives a functional and physical account of phenomenal and access consciousness while accommodating thought experiments that Block and Chalmers use to argue for their views on consciousness. Finally, while largely agreeing with the where and when of consciousness of Prinz’s AIR (Attended Intermediate Representations) theory of consciousness, QUR theory offers new arguments for an extended where and more nuanced when of phenomenal consciousness. [1] Pronounced as “cure.

The introduction of digital television in the UK: a study of its early audience

This thesis examines the diffusion and adoption of digital television (DTV) in the UK by its first generation audience. It reveals how the spread of this innovation took place, and what were its early users and uses. The main objective is to investigate the processes through which a new medium and its new audience are shaped. The study focuses on Sky digital and its subscribers, covering the first four years of the life of DTV from its launch in October 1998. My analysis draws on empirical data derived from a UK-wide postal survey of Sky digital subscribers, a series of in-depth interviews with Sky digital users, and an analysis of advertising and marketing materials. By revealing a slice of time in British media and audience history, I argue that a number of forces influence the shaping and meaning construction of a new medium. I exemplify these by analysing early DTV in terms of the circuit of culture, showing how these forces contributed to its social and cultural shaping. DTV is a hybrid medium encompassing both old and new services. In discussing how it was promoted, taken up, used and made meaningful in the lives of early users, I address wider issues of how people understand and accept novelties and whether/why they are receptive to change, or resistant to it, staying attached to old habits. In demonstrating that early users focused on the offer of more channels/bigger choice/better picture and did not rush to embrace the new interactive internet-like features of DTV, I discuss how despite the hype presenting DTV as transformative, and despite fast take-up, access to it did not necessarily equate to use of all its services. For early users, DTV was a relatively conservative enhancement of traditional TV. I argue that the introduction of a new medium entails continuity not only in technological development, but also in consumption processes, resulting in the co-existence of 'old' and 'new'. Several theoretical perspectives and methodologies are integrated in the emergent history of this now old medium when it was new. The thesis recounts DTV's biography as manifested in the moments of production and design, representation and, particularly, consumption. The thesis is informed by and adds to theories of diffusion of innovations and of domestication. Its core theoretical contribution is that, in empirically addressing the relationship between new media diffusion and social change by drawing on domestication theory, it advances the theory of diffusion of innovations, expanding its theoretical and methodological scope by examining social and cultural processes within the household and people‟s lives

Visual perception an information-based approach to understanding biological and artificial vision

The central issues of this dissertation are (a) what should we be doing — what problems should we be trying to solve — in order to build computer vision systems, and (b) what relevance biological vision has to the solution of these problems. The approach taken to tackle these issues centres mostly on the clarification and use of information-based ideas, and an investigation into the nature of the processes underlying perception. The primary objective is to demonstrate that information theory and extensions of it, and measurement theory are powerful tools in helping to find solutions to these problems. The quantitative meaning of information is examined, from its origins in physical theories, through Shannon information theory, Gabor representations and codes towards semantic interpretations of the term. Also the application of information theory to the understanding of the developmental and functional properties of biological visual systems is discussed. This includes a review of the current state of knowledge of the architecture and function of the early visual pathways, particularly the retina, and a discussion of the possible coding functions of cortical neurons. The nature of perception is discussed from a number of points of view: the types and function of explanation of perceptual systems and how these relate to the operation of the system; the role of the observer in describing perceptual functions in other systems or organisms; the status and role of objectivist and representational viewpoints in understanding vision; the philosophical basis of perception; the relationship between pattern recognition and perception, and the interpretation of perception in terms of a theory of measurement These two threads of research, information theory and measurement theory are brought together in an overview and reinterpretation of the cortical role in mammalian vision. Finally the application of some of the coding and recognition concepts to industrial inspection problems are described. The nature of the coding processes used are unusual in that coded images are used as the input for a simple neural network classifier, rather than a heuristic feature set The relationship between the Karhunen-Loève transform and the singular value decomposition is clarified as background the coding technique used to code the images. This coding technique has also been used to code long sequences of moving images to investigate the possibilities of recognition of people on the basis of their gait or posture and this application is briefly described

The Routledge Handbook of Museums, Media and Communication

Museums today find themselves within a mediatised society, where everyday life is conducted in a data-full and technology-rich context. In fact, museums are themselves mediatised: they present a uniquely media-centred environment, in which communicative media is a constitutive property of their organisation and of the visitor experience. The Routledge Handbook of Museums, Media and Communication explores what it means to take mediated communication as a key concept for museum studies and as a sensitising lens for media-related museum practice on the ground. Including contributions from experts around the world, this original and innovative Handbook shares a nuanced and precise understanding of media, media concepts and media terminology, rehearsing new locations for writing on museum media and giving voice to new subject alignments. As a whole, the volume breaks new ground by reframing mediated museum communication as a resource for an inclusive understanding of current museum developments. The Routledge Handbook of Museums, Media and Communication will appeal to both students and scholars, as well as to practitioners involved in the visioning, design and delivery of mediated communication in the museum. It teaches us not just how to study museums, but how to go about being a museum in today’s world

Artech 2008: proceedings of the 4th International Conference on Digital Arts

ARTECH 2008 is the fourth international conference held in Portugal and Galicia on the topic of Digital Arts. It aims to promote contacts between Iberian and International contributors concerned with the conception, production and dissemination of Digital and Electronic Art. ARTECH brings the scientific, technological and artistic community together, promoting the interest in the digital culture and its intersection with art and technology as an important research field, a common space for discussion, an exchange of experiences, a forum for emerging digital artists and a way of understanding and appreciating new forms of cultural expression. Hosted by the Portuguese Catholic University’s School of Arts (UCP-EA) at the City of Porto, ARTCH 2008 falls in alignment with the main commitment of the Research Center for Science and Technology of the Arts (CITAR) to promote knowledge in the field of the Arts trough research and development within UCP-AE and together with the local and international community. The main areas proposed for the conference were related with sound, image, video, music, multimedia and other new media related topics, in the context of emerging practice of artistic creation. Although non exclusive, the main topics of the conference are usually: Art and Science; Audio-Visual and Multimedia Design; Creativity Theory; Electronic Music; Generative and Algorithmic Art; Interactive Systems for Artistic Applications; Media Art history; Mobile Multimedia; Net Art and Digital Culture; New Experiences with New Media and New Applications; Tangible and Gesture Interfaces; Technology in Art Education; Virtual Reality and Augmented Reality. The contribution from the international community was extremely gratifying, resulting in the submission of 79 original works (Long Papers, Short Papers and installation proposals) from 22 Countries. Our Scientific Committee reviewed these submissions thoroughly resulting in a 73% acceptance ratio of a diverse and promising body of work presented in this book of proceedings. This compilation of articles provides an overview of the state of the art as well as a glimpse of new tendencies in the field of Digital Arts, with special emphasis in the topics: Sound and Music Computing; Technology Mediated Dance; Collaborative Art Performance; Digital Narratives; Media Art and Creativity Theory; Interactive Art; Audiovisual and Multimedia Design.info:eu-repo/semantics/publishedVersio