Quality-oriented adaptation scheme for multimedia streaming in local broadband multi-service IP networks

The research reported in this thesis proposes, designs and tests the Quality-Oriented Adaptation Scheme (QOAS), an application-level adaptive scheme that offers high quality multimedia services to home residences and business premises via local broadband IP-networks in the presence of other traffic of different types. QOAS uses a novel client-located grading scheme that maps some network-related parameters’ values, variations and variation patterns (e.g. delay, jitter, loss rate) to application-level scores that describe the quality of delivery. This grading scheme also involves an objective metric that estimates the end-user perceived quality, increasing its effectiveness. A server-located arbiter takes content and rate adaptation decisions based on these quality scores, which is the only information sent via feedback by the clients. QOAS has been modelled, implemented and tested through simulations and an instantiation of it has been realized in a prototype system. The performance was assessed in terms of estimated end-user perceived quality, network utilisation, loss rate and number of customers served by a fixed infrastructure. The influence of variations in the parameters used by QOAS and of the networkrelated characteristics was studied. The scheme’s adaptive reaction was tested with background traffic of different type, size and variation patterns and in the presence of concurrent multimedia streaming processes subject to user-interactions. The results show that the performance of QOAS was very close to that of an ideal adaptive scheme. In comparison with other adaptive schemes QOAS allows for a significant increase in the number of simultaneous users while maintaining a good end-user perceived quality. These results are verified by a set of subjective tests that have been performed on viewers using a prototype system

The contexts of use and the innovation of TV-centric network technologies: as viewers become consumer-users

This thesis seeks to explore something of the current nature of human, social and business contingencies constituting and motivating design, production, consumption and the use of technologies. It places a particular emphasis on the innovation of TV-centric network technologies - 'new' media technologies, particularly interactive television (i-Tv), intended to link, enhance or otherwise augment existing television technology and content. The empirical work in the thesis studied the development and implementation of a complex large-scale i-Tv trial in Cambridge, UK. Issues arising from the research led to the development of a general research framework - Contextual Usability (CU) - whose central aim is to draw awareness to the complex and multiple dimensions of the use process as a social and organisational construction, and also to redefine its place as an intrinsic experiential dimension in the domestication of products and services.Various senior managers and designers were interviewed within the company designing and producing the i-Tv technology and interface for the trial, as were 11 participant households. The author concludes with an overview suggesting the interconnected and interdependent nature of trials, technology, users, design, designers and organisation. For this he uses CU in relation to Molina's notion of Sociotechnical Constituencies to illustrate how social, cultural and organisational elements of trials both rely and impinge upon the implementation and interpretation of user and consumer research, and thus working 'images'of the user and the use process

Your window-on-the-world: interactive television, the BBC and the second shift aesthetics of public service broadcasting

The impetus for this project was to consider how the digitalisation of television stood as an important moment to re-evaluate key concepts and debates within television studies. To this end, my focus is on public service broadcasting and television studies' textual tradition. I examine how linear models of the television text are challenged, usurped and at times reinforced by interactive television's emergent non-linear, personalisable forms. In so doing, I am concerned to analyse interactive television's textual structures in relation to the BBC's position as a public service broadcaster in the digital television age. Across these two concerns I aim to historicise the moment of digitalisation, drawing on longer positionings of television's technological and cultural form as a 'window-on-the-world'. An introduction is followed by section 1 of the thesis that includes a review of key literature in the field, focusing particularly on work on the 'text' of television studies. The chapters in section 1 mix this review with an historical argument that understand the current digital television era as one of 'excess', placing television at the boundaries of new and old media concerns that can be usefully understood through the presence of a dialectic between television's position as window-on-the-world and its emergent position as 'portal'. Section 1 demonstrates how this dialectic is called up by the prominence of discourses of 'choice' in new media practices and textualities and, more importantly, the debates about public service broadcasting's role in the digital age. As I go on to show in section 2, this dialectic evidences a tension between the 'imaginative journeys' television's window offers and the way in which these are then 'rationalised'. The second half of the thesis maps out emergent textual forms of interactive television by analysing the way choice and mobility are structured, providing a series of case studies in non-fiction television genres. Chapter 4 demonstrates the persistence of key discourses subsumed within the window-on-the-world metaphor in the formation and 'everydaying' of interactive television, elucidating key institutional and gendered tensions in the way these discourses are mobilised in the digital age. In turn, Chapter 5 connects the kinds of mobility promised by interactive television's window to longer historical practices of public institutions regulating spectator movement. Chapter 6 examines how television's window has been explicitly remediated by interactive television, placing it within the 'database' ontologies of computing. Finally Chapter 7 demonstrates the way in which television's window increasingly comes to function as a portal through which to access digital media spaces, such as the Internet. Across the chapters I am concerned to connect the textual and discursive form of each case study to the academic debates and public service concerns of the various applications' generic identity. Although I am interested in the challenges television's digitalisation poses to both public service broadcasting and traditional television studies approaches to the text, a more important motivation has been to re-affirm the role of both in the digital television landscape. Thus through close textual analysis that connects aesthetics with production and regulation, the thesis aims to demonstrate the relevance of television studies and the BBC, as a public service broadcaster, as an 'old media' becomes a 'new' one